CN105592591B - A kind of LED drive chip condition control method of automobile reading lamp - Google Patents
A kind of LED drive chip condition control method of automobile reading lamp Download PDFInfo
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- CN105592591B CN105592591B CN201610020904.XA CN201610020904A CN105592591B CN 105592591 B CN105592591 B CN 105592591B CN 201610020904 A CN201610020904 A CN 201610020904A CN 105592591 B CN105592591 B CN 105592591B
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
- Y02B20/30—Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]
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Abstract
The present invention discloses a kind of LED drive chip condition control method of automobile reading lamp, and the OUT pins of the LED drive chip are used to connect LED；LED drive chip is according to 3 information, i.e. driving chip PWM input signals, EN pin low level pulse input signals and current LED state in which, according to jump condition and control signal output formula S S=EN_EFF, PWM_ACT, LAST_STATE_PWM, PWM_PIN, GA<1>, GA<62>, next state of LED current is judged, LED is switched in the state of 9 differences；The present invention is exported with the thought control electric current source of state machine, better than general digital display circuit control method, it is possible to achieve the need for increasingly complex function is to meet practical application.
Description
Technical field
The present invention relates to LED field technology, a kind of LED drive chip state controlling party of automobile reading lamp is referred in particular to
Method.
Background technology
The advantages of LED is with its energy-conservation, high efficiency, is increasingly widely applied to automobile lighting system.But, at present in it is low
The reading lamp at front row and heel row in shelves car generally still makees the incandescent lamp bulb of electric light source using tungsten filament.
A kind of typical prior art is as shown in Figure 1 using reading lamp solution in the car of incandescent lamp bulb.12
Volt power supply is powered, and incandescent lamp is equivalent to a resistance, puts switch for one three and includes 3 kinds of connected modes.Three, which put switch, is connected to
During the left side, incandescent lamp is constantly in illuminating state, and incandescent lamp current magnitude is determined by cell voltage divided by incandescent lamp bulb equivalent resistance
It is fixed；Three put switch when being connected to centre, and incandescent lamp current is by BCM output controls, when BCM is output as close to 0 volt of low level
Incandescent lamp is lighted, and incandescent lamp current magnitude is determined by cell voltage divided by incandescent lamp bulb equivalent resistance, and BCM is output as approximate 12 volts
During extra-high level, incandescent lamp no current bulb is in OFF state, and incandescent lamp current is approximately 0.Three, which put switch, is connected to the right
When, incandescent lamp one end connection battery, one end open circuit, electric current is 0 ampere, and incandescent lamp is in OFF state.
The brightness of incandescent lamp by being determined by its current value, by incandescent lamp current value by incandescent voltage of both ends of lamp difference divided by
The decision of incandescent lamp equivalent resistance.Due to the resistivity of incandescent lamp light emitting source tungsten filament, it can raise and increase with temperature, cause white heat
Lamp brightness is varied with temperature.The shake of cell voltage, can make incandescent voltage of both ends of lamp difference shake, cause incandescent lamp to flash.
The content of the invention
In view of this, in view of the existing deficiencies of the prior art, its main purpose is to provide a kind of automobile reading lamp to the present invention
LED drive chip condition control method, with state machine thought control electric current source export, better than general digital display circuit control
Method, it is possible to achieve the need for increasingly complex function is to meet practical application.
To achieve the above object, the present invention is using following technical scheme：
A kind of LED drive chip condition control method of automobile reading lamp, the OUT pins of the LED drive chip are used to connect
Meet LED；The LED drive chip is according to 3 information, i.e. driving chip PWM input signals, EN pin low level pulse input signals
With current LED state in which, formula is exported according to jump condition and control signal
SS=EN_EFF, PWM_ACT, LAST_STATE_PWM, PWM_PIN, GA<1>, GA<62>
Judge next state of LED current；
⑴Initial OFF：Closed mode is originated, electric original state as on driving chip is Fade patterns, EN inputs
Signal can control LED current；
⑵Fade In：The state that LED DC electric currents are incrementally increased, EN input signals control LED DC electric currents are incrementally increased
State；
⑶LED ON Due to Fade In：LED DC electric currents reach the state of maximum output value, and are made by EN inputs
The result of energy LED current；
⑷Fade Out：The state that LED DC electric currents progressively reduce, EN input signals control LED DC electric currents are progressively smaller
State；
⑸LED On Due to PWM is ON：LED DC electric current maximum output state of value, and enable is inputted by PWM
The result of LED current；
⑹LED PWM Ramp Down：PWM input signals achieve the control to LED current, and LED current
The state that dutycycle is gradually reduced；
(7) LED fade in From GA=0：LED DC electric currents are from 0 ampere of state incrementally increased, EN input signal controls
The state that LED DC electric currents processed are incrementally increased；
⑻LED PWM Ramp Up：PWM input signals achieve the control to LED current, and LED current is accounted for
The state that sky ratio gradually increases；
⑼LED PWM Mixed Fade Out：The shape that LED current is controlled simultaneously by EN input signals and PWM input signals
State.
As a kind of preferred scheme, the LED drive chip control LED operation switches between 9 kinds of states, 9 kinds of work
There are 22 paths to connect the switching of different working condition, state jump condition and the control signal output of state machine between state
Formula
SS=EN_EFF, PWM_ACT, LAST_STATE_PWM, PWM_PIN, GA<1>, GA<62>
' 0 ' represents logic low；' 1 ' represents logic high；' x ' represents any state and all set up, i.e., ' 0 ', ' 1 ' all
Meet；
(1) SS=0xx100 is worked as:next state<=S4 (Enable PWM condition), or work as SS=
1xxxxx:next state<During=S1, shift as Initial OFF states；
(2) SS=0xxx11 is worked as:next state<=S2, or work as SS=1xxxxx:next state<During=S3, turn
Move as Fade In states；
(3) SS=1xxxxxx is worked as:next state<During=S3, shift as LED on due to fade In states；
(4) SS=1xxxxx is worked as:next state<=S1, or work as SS=00x000:next state<=S0 (S3->
S0, Ask for LED offand PWM stays OFF for 30ms) when, shift as Fade Out states；
(5) SS=1xxxxx is worked as:next state<=S3, or SS=00x0xx:next state<=S0, or SS
=010xxx:next state<=S7, or SS=011xxx:next state<During=S5, shift as LED on due to
PWM is ON states；
(6) SS=00x0xx is worked as:next state<=S0, or SS=00x1xx:next state<=S4, or SS
=1xxxxx:next state<During=S6, shift as LED PWM Ramp down states；
(7) SS=0xxx11 is worked as:next state<=S2 (And SS=PWM_CONTROL_GB=0), or SS=
1xxxxx:next state<During=S3, shift as LED fade in From GA=0 states；
(8) SS=000xxx is worked as:next state<=S0, or SS=001xxx:next state<=S4, or SS
=11xxxx:next state<=S8, or SS=10xxxx:next state<During=S3, shift as LED PWM Ramp
Up states；
(9) SS=1xxxxx is worked as:next state<=S1, or SS=000x00:next state<During=S0, transfer
For LED PWM mixed fade out states.
As a kind of preferred scheme, the signal of EN pins input is low pulse control method, controls LED DC electric current with one
Constant speed degree progressively diminishes after progressively becoming greatly；The input of PWM pins is level control method, and when PWM high level is effective, PWM, which is inputted, is
LED current is set up when logically high, when PWM inputs are logic low, and it is 0 ampere that LED current, which is closed,；Similarly, when PWM has for low level
Imitate, LED current is set up when PWM inputs are logic low, when PWM inputs are logically high, it is 0 ampere that LED current, which is closed,.
As a kind of preferred scheme, EN and PWM pins input signal can control LED output current states, but EN
Input signal priority is higher than PWM input signals；When EN input signals control LEDDC electric currents incrementally increased since 0 ampere to
Maximum output current is referred to as Fade In process, until EN input signals control LED DC electric currents from maximum output current progressively
0 ampere of process for being referred to as Fade Out is reduced to, PWM inputs are ignored；
When EN controls LDE DC electric current Fade Out, until output current is gradually decreased to after 0 ampere, EN pins discharge
To LED control, and require that pwm signal at least keeps the closed mode of certain time, PWM could control LED electric current
Set up or close.
The present invention has clear advantage and beneficial effect compared with prior art, specifically, by above-mentioned technical proposal
Understand, the technology of the present invention LED drive chip is according to 3 information, i.e. driving chip PWM input signals, EN pin low level pulses
Input signal and current LED state in which, according to jump condition and control signal output formula S S=EN_EFF, PWM_ACT,
LAST_STATE_PWM, PWM_PIN, GA<1>, GA<62>Judge next state of LED current；Make LED by 22 kinds
Approach switches under 9 kinds of different conditions, and the present invention is exported with the thought control electric current source of state machine, better than general digital display circuit
Control method, it is possible to achieve the need for increasingly complex function is to meet practical application.
The technology of the present invention LED drive chip is used for automobile reading lamp, and automobile reading lamp replaces incandescent lamp, LED effects using LED
Rate is higher than incandescent lamp bulb, saves electric energy.Further, it is possible to realize following two basic functions：1st, sedan car door opening and action control of closing the door
The light on and off state of lamp processed, for example, door opening action can control lamp gradually light, closing the door can control lamp gradually to extinguish.2nd, have
One button or switch, the people being seated within a vehicle can be either manually or by touching the button or toggle switch, and control lamp is constantly in bright
State, or control lamp are in and extinguished.
More clearly to illustrate the architectural feature and effect of the present invention, come below in conjunction with the accompanying drawings with specific embodiment to this hair
It is bright to be described in detail.
Brief description of the drawings
Fig. 1 is the circuit diagram of reading lamp in prior art car；
Fig. 2 is the state transition diagram of the state machine of embodiments of the present invention；
Fig. 3 is the LED drive chip application drawing of embodiments of the present invention；
Fig. 4 is the LED drive chip structure chart of embodiments of the present invention.
Accompanying drawing identifier declaration：
1st, the first hysteresis comparator 2, filtering and logical transition module
3rd, the second hysteresis comparator 4, PWM detection modules
5th, state machine control circuit module 6, state machine output logic module
7th, electric current is gradually bright fades off control logic circuit module 8, current source module
9th, nor gate 10, OR gate
11st, with door 12, the first pierce circuit module
13rd, the second pierce circuit module 14, bandgap voltage reference module
15th, reference current circuit.
Embodiment
The present invention discloses a kind of LED drive chip condition control method of automobile reading lamp, it is adaptable to control LED automobile to read
Read lamp.The OUT pins of the LED drive chip are used to connect LED；The LED drive chip is according to 3 information, i.e. driving chip PWM
Input signal, EN pin low level pulse input signals and current LED state in which, it is defeated according to jump condition and control signal
Go out formula S S=EN_EFF, PWM_ACT, LAST_STATE_PWM, PWM_PIN, GA<1>, GA<62>Judge LED current
Next state.
The signal of EN pins input is low pulse control method, after control LED DC electric current progressively becomes big with certain speed
Progressively diminish；The input of PWM pins is level control method, and when PWM high level is effective, and PWM inputs are logically high, LED current is built
Vertical, when PWM inputs are logic low, it is 0 ampere that LED current, which is closed,；Similarly, when PWM is that low level is effective, PWM inputs are logic
LED current is set up when low, when PWM inputs are logically high, and it is 0 ampere that LED current, which is closed,.
EN and PWM pins input signal can control LED output current states, but EN input signal priority is higher than
PWM input signals；It is referred to as when EN input signals control LED DC electric currents are incrementally increased to maximum output current since 0 ampere
Fade In process, is referred to as until EN input signals control LED DC electric currents to be gradually decreased to 0 ampere from maximum output current
Fade Out process, PWM inputs are ignored；
When EN controls LDE DC electric current Fade Out, until output current is gradually decreased to after 0 ampere, EN pins discharge
To LED control, and require that pwm signal at least keeps the closed mode of certain time, PWM could control LED electric current
Set up or close.
LED state is divided into following 9 kinds of states by LED drive chip：
⑴Initial OFF：Closed mode is originated, electric original state as on driving chip is Fade patterns, EN inputs
Signal can control LED current；
⑵Fade In：The state that LED DC electric currents are incrementally increased, EN input signals control LED DC electric currents are incrementally increased
State；
⑶LED ON Due to Fade In：LED DC electric currents reach the state of maximum output value, and are made by EN inputs
The result of energy LED current；
⑷Fade Out：The state that LED DC electric currents progressively reduce, EN input signals control LED DC electric currents are progressively smaller
State；
⑸LED On Due to PWM is ON：LED DC electric current maximum output state of value, and enable is inputted by PWM
The result of LED current；
⑹LED PWM Ramp Down：PWM input signals achieve the control to LED current, and LED current
The state that dutycycle is gradually reduced；
(7) LED fade in From GA=0：LED DC electric currents are from 0 ampere of state incrementally increased, EN input signal controls
The state that LED DC electric currents processed are incrementally increased；
⑻LED PWM Ramp Up：PWM input signals achieve the control to LED current, and LED current is accounted for
The state that sky ratio gradually increases；
⑼LED PWM Mixed Fade Out：The shape that LED current is controlled simultaneously by EN input signals and PWM input signals
State.
The LED drive chip is implemented by state machine control circuit module, and control LED operation is between 9 kinds of states
There are 22 paths to connect the switching (as shown in Figure 2) of different working condition, the shape of state machine between switching, 9 kinds of working conditions
State jump condition and control signal output formula
SS=EN_EFF, PWM_ACT, LAST_STATE_PWM, PWM_PIN, GA<1>, GA<62>
' 0 ' represents logic low；' 1 ' represents logic high；' x ' represents any state and all set up, i.e., ' 0 ', ' 1 ' all
Meet；
State jump condition and the control signal output of state machine, it is as shown in the table：
State jump condition and the control signal output of the state machine of table 1
Fig. 3 is the application of the inventive method, is a kind of automobile reading lamp LED drive chip, and the LED drive chip has 8
Individual pin and peripheral circuit, 8 pins are respectively shown in table 1：
| Pin | Definition | Pin | Definition |
| 1 | EN | 5 | GND |
| 2 | ISET | 6 | OUT |
| 3 | TSTE_UP | 7 | VCC |
| 4 | TSET_DN | 8 | PWM |
Table 2
Wherein, 8 annexations between pin and peripheral circuit are as follows：VCC pin access power supply VBattery, power supply
VBatteryConnect a voltage-regulator diode, the μ F electric capacity of diodes in parallel 10, forms mu balanced circuit, shields, lead diode
It is logical in a flash, will not by high current, high-tension impact, the effect of voltage-stabiliser tube be play offer one galvanic current
Pressure, is connected in parallel with a capacitor attenuating load shock electric current.PWM pins access the level signal of certain scope limitation.EN pin phases
Connect a switch (momentary contact switch), ISET pins connect a resistance RISET, the high-speed switch, resistance it is another
One end and GND pin are grounded.OUT pins connect LED automobile reading lamp as load, are then grounded.TSTE_UP pins and
TSET_DN pins difference phase connecting resistance RTSTE_UP、RTSET_DN, then it is grounded.
Hold, the function of each pin is described in detail below：
The PWM input pins, can control output OUT pin output currents, Automatic level control mode.PWM inputs are logic
Output current is set up during high level, and PWM exports no current when input is logic low.Adjusted when needing conversion PWM duty cycle
When current source exports average current, the frequency of PWM input signals has certain scope limitation, general 50Hz~300Hz.
The EN input pins, can control OUT pin output current states.EN is that low pulse effectively controls OUT output electricity
Stream, in order to filter out other interference EN signal, EN must maintain the high level at least T1 times to subsequently become low level and low electricity
Flat maintenance at least T1 (such as T1=37ms) times, OUT output currents state can be just controlled to invert.If OUT is now
There are electric current, the reversion of OUT output currents, electric current is tapered into until being zero (regulation current source output DC electric current)；If OUT is now
No current, OUT output currents reversion, electric current is become larger until completely setting up (regulation current source output DC electric current).
The EN input pins control OUT output currents diminish or become big speed, can be by non-essential resistance RTSET_UP,
RTSET_DNSetting.RTSET_UPThe time span that LED can be set gradually to brighten, RTSET_DNThe time that LED can be set gradually to extinguish
Length.
The ISET input pins connect RISETResistance to ground, RISETResistance can set the size of OUT output currents.
The OUT is current source output pin, external connection LED load to ground.
The present invention is used as main logic unit using state machine.PWM is inputted and EN input signals can control output current
Change, chip internal design a state machine circuit, according to the feature of PWM and EN input signals, and combine cur-rent source current
State, state machine, which can make, correct to be judged to determine current source this does and how operated.
Fig. 4 is the structure chart of driving chip of the present invention, including hysteresis comparator 1 and 3, filtering and logical transition module 2,
PWM detection modules 4, state machine control circuit module 5, state machine output logic module 6, electric current is gradually bright fades off control logic circuit
Module 7, current source module 8, oscillator 12 and 13, bandgap voltage reference module 14, reference current circuit 15 etc., between each module
Circuit connection and principle be described as follows：
The EN pins input is connected to the first hysteresis comparator 1, and the Transformed E N incoming levels of the first hysteresis comparator 1 are to patrol
Collect signal output, the logical signal input filter and logical transition module 2 of the output of the first hysteresis comparator 1.Filtering and logic turn
The output EN_EFF signals of block 2 are changed the mold, this signal is used for control electric current source output current state.
EN filtering mechanism be：When EN signals are changed into high level from logic low, kept for the time of logic high surpass
Spend the T1 times (for example T1 may be configured as 37ms) and just think that low level input is changed into high level input, otherwise, this high level quilt
Shielding.Similarly, when EN signals are changed into logic low from logic high, kept for the time of logic low just think more than T1
High level input is changed into low level input, and otherwise, this low level is shielded.
Logical transition mechanism is：There is trailing edge in EN signals after detection after filtering, then invert EN_EFF signals.
The PWM pins input is connected to the second hysteresis comparator 3, and the second hysteresis comparator 3 conversion PWM incoming levels are
Logical signal is exported.The output signal of second hysteresis comparator 3 is input to PWM detection modules 4.PWM detection module functions are：Inspection
Pwm signal is surveyed either with or without with higher than frequency F1 (such as F1 is set to 30Hz) upsets.If upset, output signal PWM_ACT
It is changed into high level, otherwise without upset PWM_ACT output low levels.PWM_LAST_STATE record PWM the last time inputs are static
State during without upset (toggle frequency being less than F1 frequencies).
The connection of state machine control circuit module 5 filtering and logical transition module 2 and connection PWM detection modules 4.
The input signal of state machine control circuit module 5 has EN_EFF, PWM_ACT, PWM_LAST_STATE, GA [1], GA [62]；
Output signal is CURRENT_STATE.State machine control circuit module 5 is made and sentenced according to input signal and the state being presently in
Which kind of state is next state of breaking be, when next clock cycle arrives, and NextState assigns current state, exports current state
Signal exports logic module 6 to state machine.
The state machine output logic module 6 is connected with state machine control circuit module 5.The state machine exports logic mould
The input signal of block 6 is CURRENT_STATE, output signal include 5 signal MIX_MODE, PWM_MODE, UP, SET,
RESET.State machine output logic module 6 can reasonably control 5 output signals, details are as follows according to current state.
PWM_MODE signals, effectively, control electric current ource electric current is operated in pwm pattern to high level.PWM input control electricity
The on and off in stream source, the duty ratio of time opened by control electric current source adjusts current source and exports average current value, i.e. AC controls
Pattern.
UP signals, when PWM_MODE and MIX_MODE is low level, current source is operated in DC control models, and UP signals become
During for high level, control electric current source output DC electric current value is incrementally increased until maximum, controls current source output when being low level
DC electric current value progressively reduces until being zero.
MIX_MODE signals, effectively, control electric current source is operated in AC and DC mixing control models to high level.It is operated in mixing
During control model, GA [62:1] DC electric current value when control electric current source is opened, while pwm signal is by adjusting Duty ratio control electricity
The average value in stream source.Two kinds of control modes effectively adjust current source output current simultaneously.
Electric current is gradually bright to fade off control logic circuit module 7, this module connection status machine output logic module 6.The electric current
Gradually the bright input signal for fading off control logic circuit module 7 has this 3 data signals of UP, SET, RESET；Output signal GA [62:
1] it is 62 bits (or more bits depend on concrete application environment) data signal, control electric current source output current value is high
Level is effective.When UP signals from low level are changed into high level, and SET, RESET, when being low level, the electric current is gradually bright to fade off control
Application of logic circuit module 7 processed controls 62 output signal GA [62:1] high level is changed into certain speed successively, control electric current source is defeated
Go out electric current to incrementally increase.Similarly, when UP signals from high level are changed into low level, and SET, RESET are when being low level, the electric current
Gradually the bright control logic circuit module 7 that fades off controls 62 output signal GA [62:1] low level is changed into certain speed successively, controlled
Current source output current processed progressively reduces.SET and RESET are that high level is effective, when SET is high level, control GA [62:
1] all high level are exported, when RESET is high level, GA [62 are controlled:1] all low levels are exported.
Current source module 8, gradually the bright control logic circuit module 7 that fades off is connected input with electric current, and the state machine is defeated
Go out the MIX_MODE signals and PWM_MODE signals input nor gate 9 of logic module 6, the output signal of nor gate 9 and second
The output signal input OR gate 10 of hysteresis comparator 3, the OR gate 10 and the electric current gradually bright output for fading off control logic circuit module 7
Signal GB [62:1] input and door 11, are exported to the current source module 8, the output current of current source module 8 is drawn to OUT with door 11
Pin.Input signal includes data signal GB [62:1] exported with analog signal reference current by reference current module.Data signal
GB[62:1] 62, every 1 controls 1 low-current source respectively.The current value of each low-current source output is, 62 according to
Secondary to have low level to be changed into high level, curent change curve is nonlinear.Reference current is exported by reference current module, and ISET connects
Connecting resistance RISETTo ground.R is setISETResistance value can change the current value of current source output.
The input of first pierce circuit module 12 is TSET_UP pins and TSET_DN pins, and resistance is connected respectively
RTSET_UP、RTSET_DNTo ground.Electric current is gradually bright fades off control logic circuit module 7 for output signal connection.Resistance RTSET_UPElectric current is set
Ource electric current DC control models, the speed that current value changes from small to big controls LED by the speed that secretly brightens.Similarly, resistance RTSET_DN
It is to control LED by bright dimmed speed to set the speed of current source current value from large to small.
Second pierce circuit module 13, distinguishes the circuit moulds such as connection status machine control circuit module 5, PWM detection modules
Block, producing a reference frequency is used for the input clock of the circuit modules such as state machine control circuit module 5, PWM detection modules.
Bandgap voltage reference module 14, which produces reference voltage, is used for reference current circuit 15, the mould such as pierce circuit
Block.The modules such as the band gap and reference current circuit 15, pierce circuit are connected, the reference current circuit 15 connection current source module
8。
In summary, design focal point of the invention is：The technology of the present invention LED drive chip drives according to 3 information
Chip PWM input signals, EN pin low level pulse input signals and current LED state in which, according to jump condition and control
Signal output formula S S=EN_EFF, PWM_ACT, LAST_STATE_PWM, PWM_PIN, GA processed<1>, GA<62>Judge
Next state of LED current；LED is set to switch by 22 kinds of approach under 9 kinds of different conditions, the present invention uses the think of of state machine
Think that control electric current source is exported, better than general digital display circuit control method, it is possible to achieve increasingly complex function should to meet reality
The need for.
The technology of the present invention LED drive chip is used for automobile reading lamp, and automobile reading lamp replaces incandescent lamp, LED effects using LED
Rate is higher than incandescent lamp bulb, saves electric energy.Further, it is possible to realize following two basic functions：1st, sedan car door opening and action control of closing the door
The light on and off state of lamp processed, for example, door opening action can control lamp gradually light, closing the door can control lamp gradually to extinguish.2nd, have
One button or switch, the people being seated within a vehicle can be either manually or by touching the button or toggle switch, and control lamp is constantly in bright
State, or control lamp are in and extinguished.
The above described is only a preferred embodiment of the present invention, be not intended to limit the scope of the present invention,
Therefore any subtle modifications, equivalent variations and modifications that every technical spirit according to the present invention is made to above example, still
Belong in the range of technical solution of the present invention.
Claims (4)
1. a kind of LED drive chip condition control method of automobile reading lamp, the OUT pins of the LED drive chip are used to connect
LED；It is characterized in that：The LED drive chip is according to 3 information, i.e. driving chip PWM input signals, EN pin low level arteries and veins
Input signal and current LED state in which are rushed, according to jump condition and control signal output formula
SS=EN_EFF, PWM_ACT, LAST_STATE_PWM, PWM_PIN, GA<1>, GA<62>
Judge next state of LED current；
⑴Initial OFF：Closed mode is originated, electric original state, is Fade patterns, EN input signals as on driving chip
LED current can be controlled；
⑵Fade In：The state that LED DC electric currents are incrementally increased, the shape that EN input signals control LED DC electric currents are incrementally increased
State；
⑶LED ON Due to Fade In：LED DC electric currents reach the state of maximum output value, and input enable by EN
The result of LED current；
⑷Fade Out：The state that LED DC electric currents progressively reduce, EN input signals control LED DC electric currents progressively less shape
State；
⑸LED On Due to PWM is ON：LED DC electric current maximum output state of value, and LED electricity is enabled by PWM inputs
The result of stream；
⑹LED PWM Ramp Down：PWM input signals achieve the control to LED current, and the duty of LED current
Than the state being gradually reduced；
(7) LED fade in From GA=0：LED DC electric currents are controlled from 0 ampere of state incrementally increased, EN input signals
The state that LED DC electric currents are incrementally increased；
⑻LED PWM Ramp Up：PWM input signals achieve the control to LED current, and the dutycycle of LED current
The state gradually increased；
⑼LED PWM Mixed Fade Out：The state that LED current is controlled simultaneously by EN input signals and PWM input signals.
2. a kind of LED drive chip condition control method of automobile reading lamp according to claim 1, it is characterised in that：
The LED drive chip control LED operation switches between 9 kinds of states, has the connection of 22 paths between 9 kinds of working conditions not
With the switching of working condition, state jump condition and control signal the output formula of state machine
SS=EN_EFF, PWM_ACT, LAST_STATE_PWM, PWM_PIN, GA<1>, GA<62>
' 0 ' represents logic low；' 1 ' represents logic high；' x ' represents any state and all set up, i.e., ' 0 ', ' 1 ' all accords with
Close；
(1) SS=0xx100 is worked as:next state<=S4 (Enable PWM condition), or work as SS=1xxxxx:
next state<During=S1, shift as Initial OFF states；
(2) SS=0xxx11 is worked as:next state<=S2, or work as SS=1xxxxx:next state<During=S3, shift and be
Fade In states；
(3) SS=1xxxxxx is worked as:next state<During=S3, shift as LED on due to fade In states；
(4) SS=1xxxxx is worked as:next state<=S1, or work as SS=00x000:next state<=S0 (S3->S0,
Ask for LED offand PWM stays OFF for 30ms) when, shift as Fade Out states；
(5) SS=1xxxxx is worked as:next state<=S3, or SS=00x0xx:next state<=S0, or SS=
010xxx:next state<=S7, or SS=011xxx:next state<During=S5, shift as LED on due to
PWM is ON states；
(6) SS=00x0xx is worked as:next state<=S0, or SS=00x1xx:next state<=S4, or SS=
1xxxxx:next state<During=S6, shift as LED PWM Ramp down states；
(7) SS=0xxx11 is worked as:next state<=S2 (And SS=PWM_CONTROL_GB=0), or SS=1xxxxx:
next state<During=S3, shift as LED fade in From GA=0 states；
(8) SS=000xxx is worked as:next state<=S0, or SS=001xxx:next state<=S4, or SS=
11xxxx:next state<=S8, or SS=10xxxx:next state<During=S3, shift as LED PWM Ramp Up
State；
(9) SS=1xxxxx is worked as:next state<=S1, or SS=000x00:next state<During=S0, shift as LED
PWM mixed fade out states.
3. a kind of LED drive chip condition control method of automobile reading lamp according to claim 1, it is characterised in that：
The signal of EN pins input is low pulse control method, and control LED DC electric current progressively diminishes after progressively being become with certain speed greatly；
The input of PWM pins is level control method, and when PWM high level is effective, and PWM inputs are logically high, LED current is set up, and PWM is defeated
When entering for logic low, it is 0 ampere that LED current, which is closed,；Similarly, when PWM is that low level is effective, LED is electric when PWM inputs are logic low
Stream is set up, when PWM inputs are logically high, and it is 0 ampere that LED current, which is closed,.
4. a kind of LED drive chip condition control method of automobile reading lamp according to claim 3, it is characterised in that：
EN and PWM pins input signal can control LED output current states, but EN input signals priority is inputted higher than PWM
Signal；It is referred to as Fade In's when EN input signals control LED DC electric currents are incrementally increased since 0 ampere to maximum output current
Process, until EN input signals, which control LED DC electric currents to be gradually decreased to 0 ampere from maximum output current, is referred to as Fade Out's
Process, PWM inputs are ignored；
As EN control LDE DC electric current Fade Out, until output current is gradually decreased to after 0 ampere, the release pair of EN pins
LED control, and require that pwm signal at least keeps the closed mode of certain time, PWM could control LED electric current to build
Vertical or closing.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201610020904.XA CN105592591B (en) | 2016-01-13 | 2016-01-13 | A kind of LED drive chip condition control method of automobile reading lamp |
| US15/368,689 US9815403B2 (en) | 2016-01-13 | 2016-12-05 | LED driver chip for car reading light and state control method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201610020904.XA CN105592591B (en) | 2016-01-13 | 2016-01-13 | A kind of LED drive chip condition control method of automobile reading lamp |
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| CN105592591B true CN105592591B (en) | 2017-11-03 |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20060050522A1 (en) * | 2004-09-03 | 2006-03-09 | Tony Chen | Vehicle interior lighting assembly |
| US20060146553A1 (en) * | 2004-10-08 | 2006-07-06 | B/E Aerospace, Inc. | Dimmable reading light with emergency lighting capability |
| DE102011016420A1 (en) * | 2011-04-08 | 2012-10-11 | GM Global Technology Operations LLC (n. d. Gesetzen des Staates Delaware) | Interior lighting for a vehicle, method for providing the interior lighting in the vehicle and vehicle with the interior lighting |
| CN203744076U (en) * | 2014-02-26 | 2014-07-30 | 长安大学 | Reading lamp used in automobile |
| CN204095653U (en) * | 2014-08-29 | 2015-01-14 | 浙江吉利控股集团有限公司 | Reading lamp with an automatic light meter in a kind of vehicle chamber |
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