Background technology
Current Tablet (flat board) on the market, most of power supply chip only has software reset or the software mould with reset key
Intend hardware reset (being referred to as software reset).Software reset's shortcoming is:
1st, when system crashes, PMIC (Power Management IC, power management integrated circuit) crashes,
Now either long-press or short-press reset key, configuration processor of all having no idea reset, and PMIC is in deadlock OFF state, fails to connect
The reset signal from SOC (system level chip) is received, runs into that such case can only return factory or oneself tears battery runs down open.
For in the guarantee period, the machine of tearing open can not be guaranteed to keep in good repair, and consumer may be without corresponding instrument, so can only wait
Treat factory repair or post to repair.
2nd, cause to shut down by key and power off and start shooting.Because battery also has certain electricity, make machine not
Power consumption is carried out to battery with stopping, is that this can also be with heating, casing deformation, equivalent risk on fire untill shutdown.There are this feelings
Condition is increased and damaged if no display picture consumer can may also charge to machine.Cause to post for this and accomplish this and to machine
Device forms psychological harmful effect, and brand is had undesirable effect, while battery is due to overdischarge or overcharges, also can be right
Battery causes damage or directly damaged.
Utility model content
To solve the problems of the prior art, the utility model provides a kind of hardware reset circuit.
The utility model is connected with RTC clock chip, PMIC and battery respectively, including resets what input pin was connected with PMIC
Reset key SW1 and the power switching module being connected respectively with reset key SW1, RTC discharge modules, the power switching module
Switching and switch for controlling power supply;The RTC discharge modules are used for when system power supply disconnects, and RTC clock chip is broken
Electricity.
The utility model is further improved, in addition to electrostatic protection module, the electrostatic protection module and reset key
SW1 pins 1 are connected.
The utility model is further improved, and the electrostatic protection module is transient voltage suppressor, the transition
Voltage suppression diode one end is connected with reset key SW1, the transient voltage suppressor other end ground connection.
The utility model is further improved, and power switching module includes metal-oxide-semiconductor Q7, electric capacity C204, electric capacity C203, described
Metal-oxide-semiconductor Q7 source electrodes are connected with anode VBAT, and the metal-oxide-semiconductor Q7 drain electrodes are connected with system voltage input VBAT_IN, described
System voltage input VBAT_IN is grounded by electric capacity C203, and the anode VBAT is grounded by electric capacity C204, described
Metal-oxide-semiconductor Q7 grids are grounded by resistance R199 and resistance R202, are connected by resistance R199 with reset key SW1 pins 3, described
Reset key SW1 pins 1 meet anode VBAT by resistance R196.
The utility model is further improved, in addition to resistance R195, the terminating systems control sources of resistance R195 mono-
Hold VBAT_IN, another termination anode VBAT.
The utility model is further improved, and the RTC discharge modules include triode Q8, resistance R198, electric capacity C205,
The triode Q8 base stages are connected by resistance R200 with reset key SW1 pins 3, and the triode Q8 colelctor electrodes pass through resistance
R198 is connected with RTC3.3V voltages, the triode Q8 grounded emitters, described electric capacity C205 one end and RTC3.3V voltage phases
Even, the electric capacity C205 is grounded anotherly.
Compared with prior art, the beneficial effects of the utility model are:Circuit is simple and safe, after reset key is pressed, institute
The function element for having reset can just be triggered, and effectively realize that system cut-off resets;Response is rapid, and can protect battery, Bu Huizao
Into the damage or damage of battery;Compatible software reset function.
Embodiment
The utility model is described in further details with reference to the accompanying drawings and examples.
As shown in figure 1, the utility model respectively with RTC (real-time clock, real-time clock) clock chip, PMIC
It is connected with battery, including the input pin reset key being connected and the power switch mould being connected respectively with reset key is resetted with PMIC
Block, RTC discharge modules, the power switching module are used for switching and the switch for controlling power supply;The RTC discharge modules are used to work as
When system power supply disconnects, make RTC clock powering down chips.The corresponding software reset of the utility model, circuit is simple and safe, is pressing
After reset key, the function element of all resets can just be triggered, and effectively realize that system cut-off resets;Response is rapid, and can protect
Battery, does not result in the damage or damage of battery.
As depicted in figs. 1 and 2, this example also includes electrostatic protection module, and the electrostatic protection module is drawn with reset key SW1
Pin 1 is connected.The electrostatic protection module of this example is transient voltage suppressor, and described transient voltage suppressor one end is with answering
Position button SW1 is connected, the transient voltage suppressor other end ground connection.In addition, the transient voltage suppressor of this example
Also it is connected by resistance R196 with anode BAT, can be just discharged at once when hand touches button.One is also reserved on circuit
Resistance R203 resets input pin with PMIC and is connected, and system power supply VBAT and PMIC reset GPIO pin can be protected well.
The power switching module of this example includes metal-oxide-semiconductor Q7, electric capacity C204, electric capacity C203, the metal-oxide-semiconductor Q7 source electrodes and battery
Positive pole VBAT is connected, and the metal-oxide-semiconductor Q7 drain electrodes are connected with system voltage input VBAT_IN, the system voltage input
VBAT_IN is grounded by electric capacity C203, and the anode VBAT is grounded by electric capacity C204, and the metal-oxide-semiconductor Q7 grids pass through
Resistance R199 and resistance R202 ground connection, is connected by resistance R199 with reset key SW1 pins 3, the reset key SW1 pins
1 meets anode VBAT by resistance R196.
Anode VBAT and electric capacity C204 formation filtering and protection metal-oxide-semiconductor Q7, VBAT are arrived by metal-oxide-semiconductor Q7 source electrode
Drain electrode is connected to VBAT_IN, is acted on as battery switching, VBAT_IN and electric capacity C203 formation filter actions.In addition, VBAT with
A reserved resistance R195 compatible software, which resets, in the middle of VBAT_IN uses.Metal-oxide-semiconductor Q7 grid passes through two resistance eutral groundings, as
Signal control action, by making resistance R202 in metal-oxide-semiconductor Q7 on and off, Fig. 2 to metal-oxide-semiconductor Q7 grids high level or bottom level
A low electric signal is kept by resistance R199 to grid with metal-oxide-semiconductor Q7 over the ground, metal-oxide-semiconductor Q7 is given tacit consent to conducting state.
This example RTC discharge modules include triode Q8, resistance R198, electric capacity C205, and the triode Q8 base stages pass through electricity
Resistance R200 is connected with reset key SW1 pins 3, and the triode Q8 colelctor electrodes are connected by resistance R198 with RTC3.3V voltages,
The triode Q8 grounded emitters, described electric capacity C205 one end is connected with RTC3.3V voltages, and the electric capacity C205 connects anotherly
Ground.
Reset key SW1 is connected by resistance R200 with the triode Q8 of RTC discharge modules base stage, triode Q8 is existed
Collector and emitter is turned on when receiving discharge signal makes RTC electric capacity C205 discharge by resistance R198, system is broken completely
Electricity.
The metal-oxide-semiconductor Q7 of this example manages for AO3401 or Equivalent A O3401 P, and triode Q8 is 8050 or equivalent 8050 NPN
Pipe.
This example is a manual key hardware reset circuit, and in the case of no reset signal, power switching module exists
Normally work, powered to system PMIC, RTC discharge modules are being not connected to discharge signal, RTC clock chip holding work shape
State.After reset key is pressed, the function element of all resets can just be triggered, and play reset systemic effect.
Operation principle of the present utility model is:
Battery is connected first, and metal-oxide-semiconductor Q7 source electrode is connected to the energization of battery VBAT positive poles, the source electrode electricity of metal-oxide-semiconductor Q7 now
Press and come from battery, upper electricity, metal-oxide-semiconductor Q7 grid is by two resistance eutral groundings, and metal-oxide-semiconductor Q7 grid is now changed into low level, MOS
Pipe Q7 is turned on, and voltage goes to drain electrode from source electrode, drain electrode is had voltage, and electric capacity C203 keeps stabilization to be sent to after filtering
On VBAT_IN, system power supply PMIC normal works.
When needing to reset, reset key SW1 is pressed, if human body carries electrostatic, and is gone here and there into now transient voltage
Suppress diode ESD pipes by impacting with high pressure, ESD pipes spark, protection device, while VBAT voltages pass through reset key SW1
By resistance R199, it is sent to metal-oxide-semiconductor Q7 grid and is powered on, metal-oxide-semiconductor Q7 source electrodes ends to VBAT_ with draining into high-impedance state
IN powers, and system power supply disconnects, while voltage is by another road resistance R200, electricity in triode Q8 base stage, triode Q8's
Colelctor electrode is turned on emitter stage, and VRTC3V3 voltages deposit electric capacity C205 to ground by resistance R198, triode Q8 emitter stages
Electricity bleed off, because this group of electric capacity is smaller, moment discharges electricity, makes RTC clock powering down chips, RTC clock chip due to
Without electricity, stop timing and provide clock signal to outside, be electrically turn off, reach to now, PMU (PMU) is all
The requirement of reset system.
Embodiment described above is better embodiment of the present utility model, and it is new not to limit this practicality with this
The specific implementation scope of type, scope of the present utility model includes being not limited to present embodiment, all according to the utility model
The equivalence changes made are in protection domain of the present utility model.