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no. ea-076-0012 negative output charge pump regulator (100ma) r1250v1a series application manual
negative output charge pump regulator (100ma) r1250v1a series 1 outline the r1250v 1a series are negative output charge pump regulator ics, which can be developed as local power suppliers for portable appliances and small electric appliances used with batteries, with low supply current by cmos process. each of these ics consists of an oscillator, a control circuit, a reference voltage unit, an error amplifier, and an out- put driver circuit. the r1250v 1a can easily supply negative voltage, or regulated setting output voltage in the range from -2v to -4v from positive input voltage. the chip enable function works to shut down the internal circuit and reduces supply current at the stand-by mode, therefore the r1250v 1a is very suitable for the application such as portable systems that require low supply cur- rent. since the package for this ic is tssop8 package (tsop8 in eiaj standard), high density mounting of the ics on board is possible. features ? output current..................... 100ma (max. at v in =5.0v, c in =c p =c out =4.7f, set output voltage=-3.0v) ? output voltage accuracy...... 3.0% (v in =5.0v, c in =c p =c out =4.7f, set output voltage=-3.0v, i out =0ma/10ma) 9.0% (v in =5.0v, c in =c p =c out =4.7f, set output voltage=-3.0v, i out =50ma) ? output voltage...................... stepwise setting with a step of 0.1v in the range from -2.0v to -4.0v is possible. ? range of input voltage ......... ? v out ? v to +5.5v (set output voltage=-4.0v to -2.8v) +2.7v to +5.5v (set output voltage=-2.7v to -2.0v) ? oscillator frequency ............ typ. 280khz ? chip enable function (active at ?l?) ? package ................................. tssop8 applications ? power source for disk drives. ? power source for hand-held communication equipment and battery-powered equipment. ? power source for pc peripherals and add-on cards. ? power source for portable audio-visual appliances such as cameras. ? local power source for small electrical appliances.
r1250v1a 2 block diagram v in v out 13 2 7 6 sw1 sw3 sw4 sw2 8 4 gnd ce r o r pu osc vref vref c p+ c p- pin configuration tssop8 1 3 2 4 c p+ c p - gnd ce 8 6 7 5 v in vref v out nc package dimension 1 2 3 4 8 7 6 5
r1250v1a 3 pin description pin no. symbol description 1c p+ c p (capacitor for charge pump) positive power supply pin 2 gnd ground pin 3c p- c p (capacitor for charge pump) negative power supply pin 4 ?? ce chip enable pin (active at ?l?) 5 nc no connection pin 6 vref output pin for reference voltage (*note1) 7v out output pin for negative regulator 8v in power supply pin *note1 vref is just a monitoring pin, therefore remain open. do not connect any load. refer to techni- cal notes. absolute maximum ratings (gnd=0v) symbol item rating unit v in v in supply voltage -0.3 to 7.5 v v ce ?? ce pin input voltage -0.3 to v in +0.3 v v p+ c p+ pin input voltage -0.3 to v in +0.3 v vref vref pin voltage -0.3 to v in +0.3 v v p- c p - pin input voltage v in -12 to +0.3 v v out v out pin voltage v in -12 to +0.3 v i out output current 200 ma p d power dissipation *note1 490 mw topt operating temperature range -40 to +85 c tstg storage temperature range -55 to +125 c *note1: power dissipation is specified under the specified condition. conditions; evaluation board dimensions: 50mm 50mm 1.6mm material: glass epoxy (fr-4) reverse side of the evaluation board: plane copper surface of the evaluation board: land pattern and wiring
r1250v1a 4 selection guide the output voltage and the active type for the ics can be selected at the user?s request. the selection can be made with designating the part number as shown below; r1250v 1a- abc code contents a setting output voltage : the absolute value of output voltage stepwise setting with a step of 0.1v in the range of -2.0v to -4.0v is possible. b designation of active type of the chip enable circuit: a (fixed) : ?l? active type c designation of packing type e2 : e2 1reel=2000pcs
r1250v1a 5 electrical characteristics r1250v 1a (unless otherwise provided, v in =5.0v, topt=25 c, c p , c out = ceramic 4.7f) symbol item conditions min. typ. max. unit set output voltage = -2.7v to -2.0v 2.7 v in operating input voltage set output voltage = -4.0v to -2.8v | set v out | 5.5 v -2.4v to -2.0v 1.50 2.30 -2.9v to -2.5v 1.60 2.55 -3.4v to -3.0v 1.70 2.75 i ss supply current operation: active, for ic itself *note1 -4.0v to -3.5v 1.80 3.00 ma i stb shut-down current operation: shut-down, for ic itself *note2 0.1 1 a -2.4v to -2.0v 0.95 1.05 -2.9v to -2.5v 0.96 1.04 -3.4v to -3.0v 0.97 1.03 i out =0ma/10ma -4.0v to -3.5v 0.97 1.03 i out =50ma -2.4v to -2.0v 0.88 1.12 -2.9v to -2.5v 0.89 1.11 -3.4v to -3.0v 0.91 1.09 v out output voltage i out =75ma -4.0v to -3.5v 0.92 1.08 v vref reference voltage *note3 no load ? v out ? v i out =10ma to 50ma -2.4v to -2.0v ? v out / ? i out load regulation i out =10ma to 75ma -4.0v to -2.5v 0.7 mv/ ma fosc oscillator frequency output frequency 238 280 322 khz ? fosc/ ? t oscillator frequency temperature coefficient 0.25 khz/ c duty oscillator duty cycle at no load 50 % v sdh ce ?h? input voltage 1.5 v v sdl ce ?l? input voltage 0.25 v r pu ce pull-up resistance 0.68 1.25 3.00 m ? r o resistance between v out and gnd 5k ? *note1 refer to test circuit 1. *note2: refer to test circuit 6. *note3: do not connect ant load. refer to technical notes. *use ceramic capacitors with low esr. capacitors with high esr could have bad effect on the performance of this ic.
r1250v1a 6 typical characteristics 1) supply current at no load vs. input voltage 2) supply current at no load vs. temperature r1250v 1a r1250v 1a 2.000 2.500 1.500 1.000 0.500 0.000 input voltage v in (v) 2.5 3.0 -3.0v output -2.0v output -4.0v output 4.0 5.0 4.5 5.5 3.5 supply current at no load i ss2 (ma) 2.0 2.5 1.5 1.0 0.5 0.0 temperature topt ( c) -50 -25 -3.0v output -2.0v output -4.0v output 25 75 50 100 0 supply current at no load i ss2 (ma) 3) input current vs. output load current 4) efficiency vs. load current r1250v301a r1250v 1a 100 120 80 60 40 20 0 output load current i out (ma) 0 20 60 100 80 120 40 input current i in (ma) 80 100 60 40 20 0 020 -3.0v output -2.0v output -4.0v output v in =loutputl+1v 60 100 80 120 40 efficiency (%) output load current i out (ma) 5) oscillator frequency vs. input voltage 6) oscillator frequency vs. temperature r1250v201a r1250v201a 310 300 320 290 280 270 260 250 240 input voltage v in (v) 2.5 3 4 5 4.5 5.5 3.5 oscillator frequency fosc (khz) temperature topt ( c) 298 296 294 300 292 290 288 286 284 282 280 -50 -25 25 75 50 100 0 oscillator frequency fosc (khz)
r1250v1a 7 7) output voltage vs. output load current r1250v201a r1250v201a -1.9 -2 -2.1 output load current i out (ma) 0 20 60 100 80 120 40 output voltage v out (v) v in =5.0v 85 c 50 c 25 c output load current i out (ma) output voltage v out (v) 85 c 50 c 25 c v in =3.0v -1.6 -1.7 -1.5 -1.8 -1.9 -2 -2.1 -2.2 0 20 60 100 80 120 40 r1250v301a r1250v301a -2.9 -3 -3.1 output load current i out (ma) 0 20 60 100 80 120 40 output voltage v out (v) 85 c 50 c 25 c v in =5.0v output load current i out (ma) output voltage v out (v) 85 c 50 c 25 c v in =4.0v -2.6 -2.7 -2.5 -2.8 -2.9 -3 -3.1 -3.2 0 20 60 100 80 120 40 r1250v401a output voltage load current i out (ma) output voltage v out (v) 85 c 50 c 25 c v in =5.0v -3.6 -3.7 -3.5 -3.8 -3.9 -4 -4.1 -4.2 0 20 60 100 80 120 40
r1250v1a 8 8) output voltage vs. temperature r1250v201a r1250v301a -1.99 -1.98 -2.00 -2.01 -2.02 temperature topt ( c) -50 -25 25 75 50 100 0 output voltage v out (v) -3.05 -3.03 -3.03 -3.02 -3.01 -3.00 -2.99 temperature topt ( c) -50 -25 25 75 50 100 0 output voltage v out (v) r1250v401a -4.06 -4.05 -4.04 -4.03 -4.02 -4.01 -4.00 -3.99 -3.98 temperature topt ( c) -50 -25 25 75 50 100 0 output voltage v out (v) 9) output voltage waveform -3.00v 100mv 1.00 s unless otherwise provided, conditions are as follows; sample: r1250v301a v in =5.0v c in =c p =c out =4.7f i out =0ma bw=20mhz
r1250v1a 9 -3.00v 100mv 1.00 s i out =10ma -3.00v 100mv 1.00 s i out =50ma test circuits test circuit 1) supply current 1 test circuit 2) typical characteristics 1), 2) test circuit 3) typical characteristics 3), 4), 7), 8) test circuit 4) typical characteristics 5), 6) test circuit 5) typical characteristics 9) test circuit 6) standby current 1) test circuit 1 a a 5.5v i ss -p i ss -n set output voltage+0.2v 1.c p+ 3.c p - 2.gnd 4.ce 8.v in 6.vref 7.v out 5.nc i ss1 =i ss -p+i ss -n (*) to stabilize voltage, a few f bypass capacitors are applied to v out pin and v in pin.
r1250v1a 10 2) test circuit 2 a 4.7 f 4.7 f 4.7 f 1.c p+ 3.c p- 2.gnd 4.ce 8.v in 6.vref 7.v out 5.nc i ss2 3) test circuit 3 v a 4.7 f 4.7 f 4.7 f 1.c p+ 3.c p- 2.gnd 4.ce 8.v in 6.vref 7.v out 5.nc i in i out (|v out | i out )/(v in i in ) 100(%) 4) test circuit 4 1.c p+ 3.c p- 2.gnd 4.ce 8.v in 6.vref 7.v out 5.nc oscilloscope (*) to stabilize voltage, a few f bypass capacitor is applied to v in pin.
r1250v1a 11 5) test circuit 5 a 4.7 f 4.7 f 4.7 f 1.c p+ 3.c p- 2.gnd 4.ce 8.v in 6.vref 7.v out 5.nc i in i out oscilloscope bw:20mhz 5.0v 6) test circuit 6 a 7.5v 1.c p+ 3.c p- 2.gnd 4.ce 8.v in 6.vref 7.v out 5.nc typical application 4.7 f 4.7 f output c p+ c p- gnd ce v in vref v out nc open c p c in c out 4.7 f (*) vref pin should not be wired. refer to technical notes.
r1250v1a 12 operation 1) basic operation the r1250v 1a series make sw1 through sw4 on and off by the clock generated by internal oscillator (osc) with fixed frequency, and operate as a inverting charge pump with the capacitor c p and the capacitor c out . the output voltage is feedback and the voltage between the output voltage and reference voltage (vref = ? v out ? v) is divided half, and it is compared with the gnd (=0v) level by an internal operational amplifier. by this action, the impedance of sw3 is controlled to correspond with its load current and output voltage keeps ?set v out ? level. 2) status of internal circuits at standby mode and standby current at standby mode, r1250v series keep the voltage of c p as shown below: v in c in c p r o r out c out v out up to 5k ? r1250v 1a when you design a system with using this ic, consider the following subjects; 2-(1) if very small leakage current would be a critical, the leakage current of both c in and c p should be considered. 2-(2) because the voltage level of c p keeps as much as v dd level, the speed for start-up from stand-by mode is faster than the start-up by power-on. 2-(3) v out is internally pulled down through 5k ? to gnd. time constant ? ? of transient response (turn-off speed) of v out can be calculated as follows: ? (5[k ? ] ?? r out ) c out (r out : output load resistance) 2-(4) load current should be off synchronously with this ic if the load is electronic or connected between v in and v out . if some charge is continuously flown to the output v out at the ?off? state, the voltage level of v out will rise and could be beyond 0v. and if the voltage will be +0.3v (that is designated as absolute maximum rating.), this ic might be break down. 3) ripple voltage ripple voltage of output waveform can be roughly calculated as follows: vripple [mvp-p] ? 0.5 (i out [ma] + supply current at no load [ma]) / (oscillator frequency: 280000 [hz]) / c out [f] supply current at no load [ma] ? supply current 1 [ma]
r1250v1a 13 4) power consumption power consumption at large load current of this ic can be calculated as follows: wchip [mw] ? (v in [v]-| set output voltage |) (i out [ma]) technical notes to use this ic, the following things should be considered. 1) short protection function for each pin is not included in this ic. 2) use capacitors with low equivalent series resistor (esr) for c in , c p , c out pins. capacitors with large esr make this ic?s performance worse. 3) make wiring of gnd, v in , c p+ , c p- secure enough and decrease impedance. high impedance could be a cause of unstable operation of this ic. 4) when this ic is used with large load current, consider its radiation of heat. 5) basically, vref pin can be used for soldering to the mount pad of pcb. do not make it wiring. 6) load type is electronic or setting between v in and v out , in cases of off-state of this ic and start-up state of this ic, make sure not to raise v out level on positive voltage side. if the voltage level is beyond +0.3v, which is desig- nated as the absolute maximum rating, this ic could be broken.

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