Summary of the invention
For solving above-mentioned existing shortcoming, the low-power consumption boost type DC-DC transducer that main purpose of the present invention is to provide a kind of ultralow pressure of practicality to start, the low-power consumption boost type DC-DC transducer that can under ultralow input voltage, start, this DC-DC boost converter can start and operate as normal under the condition of single battery (1.2V) power supply, operating current is lower than 100uA, and the automatic stand-by function is arranged, when output does not have load, automatically enter standby, average current is lower than 1uA during standby, is particularly suitable for the application of boosting of mobile phone backup power, portable power source.
For reaching above-described purpose, the low-power consumption boost type DC-DC transducer that a kind of ultralow pressure of the present invention starts is taked following technical scheme:
The low-power consumption boost type DC-DC transducer that a kind of ultralow pressure starts; it is characterized in that the connection of control chip 100 internal fixation arranges internal electric source and selects 101; internal reference and biasing 102; PMOS power tube (high-side) 103; NMOS power tube (low-side) 104; inductive current detecting resistance 105; lead-edge-blanking unit 106; Cycle by Cycle overcurrent protection comparator 107; PWM (pulse-width modulation) comparator 108; control logic and driving 109; oscillator 110; ultralow pressure oscillator 111; standby signal handles 112; unloaded detecting comparator 113; error amplifier 114; output voltage feedback divider resistance 115; output voltage feedback divider resistance 116; control switch 118 and enable 117.
Described control chip 100 has four pins, is respectively switch pin SW, enable pin EN, output pin Vout and GND pin.
Adopt as above the present invention of technical scheme, have following beneficial effect:
The low-power consumption boost type DC-DC transducer that can under ultralow input voltage, start, this DC-DC boost converter can start and operate as normal under the condition of single battery (1.2V) power supply, operating current is lower than 100uA, and the automatic stand-by function is arranged, when output does not have load, automatically enter standby, average current is lower than 1uA during standby, is particularly suitable for the application of boosting of mobile phone backup power, portable power source.
Embodiment
To be described further by the present invention of embodiment below, the description of these embodiment is not that content of the present invention is done restriction.One skilled in the art will understand that to be equal to replacement to what content of the present invention was done, or corresponding the improvement, still belong within protection scope of the present invention.
As shown in Figure 1, the low-power consumption boost type DC-DC transducer that a kind of ultralow pressure of the present invention starts, wherein control chip 100 has four pins, is respectively switch pin SW, connects input voltage by inductance; Enable pin EN is used for importing high/low level by the outside and determines whether chip 1 is opened; Output pin Vout is used for the output voltage that (such as 5V) fixed in output; The GND pin is as the reference ground of entire chip.The connection of control chip 100 internal fixation arranges internal electric source and selects 101; internal reference and biasing 102; PMOS power tube (high-side) 103; NMOS power tube (low-side) 104; inductive current detecting resistance 105; lead-edge-blanking unit 106; Cycle by Cycle overcurrent protection comparator 107; PWM (pulse-width modulation) comparator 108; control logic and driving 109; oscillator 110; ultralow pressure oscillator 111; standby signal handles 112; unloaded detecting comparator 113; error amplifier 114; output voltage feedback divider resistance 115; output voltage feedback divider resistance 116; control switch 118 and enable 117.Internal electric source selects 101 for generation of built-in power supply, give chip internal each device power supply, it compares SW voltage and Vout voltage by internal comparator, which voltage ratio is higher, just select this voltage as internal electric source, therefore SW voltage equals input voltage vin before chip does not have startup, and Vout voltage is provided by the body diode of PMOS power tube 103 by SW, therefore Vout voltage ratio SW voltage is low, so the internal power supply of chip is SW at this moment; Behind the boost DC-DC chip enable, output voltage begins slowly to raise, and finally is higher than SW voltage, and therefore, the chip internal power supply switches to output voltage V out and provides.Internal reference and biasing 102 are for generation of reference voltage ref1, ref2, ref3 etc., and needed bias current when respectively installing operate as normal, also produce benchmark simultaneously and set up the signal PG of OK, after supply voltage is elevated to a certain degree, internal reference and biasing 102 ability operate as normal, this moment, PG was high level by the low level upset, it is enough high to represent chip power, can make inside respectively install operate as normal, the most of analog circuit of chip internal just begins operate as normal after the PG upset.During as NMOS power tube 104 conductings of low-side; SW is grounded by inductive current detecting resistance 105; inductance two ends pressure differential deltap V is near output voltage V in; inductive current begins to rise; when inductive current rises to Cycle by Cycle overcurrent protection threshold value or NMOS power tube 104 ON time and reaches the duty ratio that is determined by PWM comparator 108; switch NMOS power tube 104 turn-offs; PMOS power tube 103 conductings as high-side; give the inductance afterflow; inductive current flows into Vout from Vin, provides energy to output.The real-time current of inductance when inductive current detecting resistance 105 is used for 104 conductings of detecting low-side NMOS power tube; through being input to PWM comparator 108 after the various possible interference of lead-edge-blanking 106 filterings; compare with error amplifier 114 output signal comp and to decide the conducting duty ratio of switch NMOS power tube 104; thereby participate in loop control; in addition in order to guarantee the safety of system; the CS signal also is sent to Cycle by Cycle overcurrent protection comparator 107; ref2 compares with internal reference voltage; once inductive current reaches the overcurrent protection threshold value, switch NMOS power tube 104 turn-offs immediately.Output voltage feedback divider resistance 115 and output voltage feedback divider resistance 116 are formed feedback network, output voltage is fed back to error amplifier 114, and compare with internal reference voltage ref1, when output voltage was low, feedback voltage FB was less than ref1, and then the output comp voltage of error amplifier 114 raises, NMOS power tube 104 conducting duty ratios increase, each cycle increases to the energy that output transmits, and output voltage slowly raises, and finally is stabilized in set point.In addition, when output loading reduces, comp voltage also can reduce so that the conducting duty ratio of switch NMOS power tube 104 reduces, when load is reduced to a certain degree, illustrate that load (mobile phone or other electronic equipment) charging of boosting has been full of, when then comp is reduced to less than internal reference voltage ref3, the output signal noload of unloaded detecting comparator 113 is high level by the low level upset, and be input to standby signal and handle 112, standby signal handles 112 through exporting standby shutdown signal OFF after the of short duration time-delay, the OFF signal is input to each device, it can be with the device Close All except ultralow pressure oscillator 111, simultaneously feedback network is also cut off, to reduce power consumption, shut-in time be Toff (several seconds approximately) during this period of time chip internal have only ultralow pressure oscillator 111 and standby signal to handle 112 in work, the operating current of chip is lower than 1uA; Toff is after the time, the upset of OFF signal is low level, each module of chip internal begins operate as normal again, output voltage can be set up within 1ms, and detect output loading again, if output is still unloaded, then after opening 1ms, the noload signal overturns again, the OFF signal overturns thereupon and is high level, internal electric source selects 101 to cut out Toff again, that is to say that chip can be opened 1ms (as shown in Figure 4) every several seconds when output is unloaded, the whole so average opening time when unloaded has only several one thousandths, the electric current of system consumption also can be less than 1uA, thereby guarantees extremely low stand-by power consumption, is particularly conducive to utilization ratio and the service time of improving portable power source.(be lower than 2V) when input voltage vin is very low, the analog circuit unit of general chip internal, particularly internal reference circuit and Ge Lu bias current can't operate as normal, and therefore general chip can't start.Ultralow pressure oscillator 111 is used in input voltage vin very low (such as by single-unit 1.5V powered battery, cell voltage may be low to moderate 1.2V) time, clocking is used for PMOS power tube 103 and NMOS power tube 104, chip also can be started under ultralow input voltage, will begin behind the chip enable provides energy to output end vo ut, make output voltage rise, select 101 effect then by internal electric source, commentaries on classics is given inner each module for power supply by Vout, when Vout is elevated to a certain degree, inner each analog circuit unit energy operate as normal, the upset of PG signal is high level, ultralow pressure oscillator 111 quits work at this moment, and oscillator 110 begins to provide the control switch of clock signal participation accurately pipe for chip.When chip detects zero load, when entering standby, internal module all quits work, and the ultralow pressure oscillator is started working again, for the standby signal processing unit provides clock, to be used for timing Toff duration.Oscillator 110 also can be exported a sawtooth signal except clock signal CLK, be used for being superimposed upon inductor current signal, as slope compensation, greater than 50% o'clock, guarantees the stability of system with convenient NMOS power tube 104 conducting duty ratios.Whether enable the unit is used for deciding chip to open according to the signal EN of outside enable pin input, the inside enable signal Enable of its generation is input to each module, the operating state of inner all unit of control, when EN is high level, chip is started working, when EN was low level, chip was not worked, and current sinking is zero.Control logic and driver element 109 are used for coming according to each input signal the break-make of control switch PMOS power tube 103 and NMOS power tube 104.
As shown in Figures 2 and 3, as long as input voltage vin is higher than the unlatching threshold value (the about 0.7V of Vth) of common CMOS technology device, just can start working clocking.It is end to end by the unit 130 of five repetitions, and control logic 150 is formed.Wherein repetitive 130 is by resistance 131,132, and electric capacity 133 and nmos switch pipe 134 are formed; Wherein an end of an end of resistance 133 connection resistance 132 connects the drain terminal of the switching tube of the 5th repetitive simultaneously, another termination internal electric source vdd of resistance 131, the other end of resistance 132 connects the top crown of electric capacity 133 and the grid of switching tube 134, the bottom crown ground connection of electric capacity 133, the drain terminal of switching tube 134 connects two resistance intermediate nodes of second unit, the source end of switching tube 134 connects the drain terminal of switching tube 156 in the control logic, and used repetitive cascaded series successively circularizes oscillator; Control logic 150 is by inverter 151,153, with door 152,155, NAND gate 154, PMOS switching tube 157 and nmos switch pipe 156 are formed, wherein the input of inverter 151 connects the node 201 in the repetitive 130,151 output connects an input with door 152, another input of 152 connects the node 204 of the 4th repetitive, 152 output is ultralow pressure clock signal clk 1, the input of inverter 153 connects the noload signal, input connects an input of NAND gate 154, another input of 154 connects the PG signal, 154 output connects an input with door 155, and another input of 155 connects the Enable signal, and 155 output connects the grid of switching tube 157 and 156, the source electrode of PMOS switching tube 157 meets internal electric source vdd, 157 drain electrode connects the resistance intermediate node 211 of first repetitive, and the drain electrode of nmos switch pipe 156 connects the source electrode of the nmos switch pipe 134 of all repetitives, 156 source ground.When enable signal Enable is high level, chip will be started working, if this moment, input voltage was lower, internal electric source vdd is not high enough, be that PG is when being low level or chip when being in unloaded standby closed condition noload and being high level, ring oscillator is started working, and its each main nodes waveform as shown in Figure 3.Ultralow pressure clock signal clk 1 directly drives PMOS power tube 103 and NMOS power tube 104, and switch NMOS power tube 104 makes output voltage V out raise gradually with 80% fixing duty ratio conducting, and at this moment, loop does not also have work, and is inoperative.When enable signal is low level, perhaps Vout is elevated to a certain degree, internal electric source is high to making each module operate as normal, be that PG be that high level and system be in non-holding state is that noload is when being low level, ultralow pressure oscillator 111 quits work, clock is provided by oscillator 110, the loop control output voltage that begins to work.