LT1373 Linear Technology Corporation, LT1373 Datasheet
LT1373
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LT1373 Summary of contents
Page 1
... All functions of the LT1373 are integrated into 8-pin SO/PDIP packages. Compared to the 500kHz LT1372, which draws 4mA of quiescent current, the LT1373 switches at 250kHz, typi- cally consumes only 1mA and has higher efficiency. High frequency switching allows for small inductors to be used. ...
Page 2
... LT1373 ABSOLUTE AXI U RATI GS (Note 1) Supply Voltage ....................................................... 30V Switch Voltage LT1373 ............................................................... 35V LT1373HV .......................................................... 42V S/S Pin Voltage ....................................................... 30V Feedback Pin Voltage (Transient, 10ms) .............. 10V Feedback Pin Current ........................................... 10mA Negative Feedback Pin Voltage (Transient, 10ms) ............................................. 10V Operating Junction Temperature Range Commercial ........................................ 125 C* Industrial ......................................... – ...
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... Note 2: For duty cycles (DC) between 50% and 90%, minimum guaranteed switch current is given by I Switch Current Limit vs Duty Cycle 3.0 2 AND 125 C 2.0 –55 C 1.5 1.0 0 100 DUTY CYCLE (%) LT1373 • G02 LT1373 = MIN TYP MAX UNITS 0.5 0.85 1.5 1.9 2.7 A 1.3 1.7 2.5 A ...
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... FEEDBACK PIN VOLTAGE (V) LT1373 • G05 Error Amplifier Transconductance vs Temperature 500 400 300 200 100 0 –50 – 0.9 1.0 TEMPERATURE ( C) LT1373 • G08 Negative Feedback Input Current vs Temperature NFB NFR –2 –4 –6 –8 –10 –12 –14 –16 –18 –20 –50 – ...
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... IN minimize radiation and voltage spikes LOW DROPOUT 2.3V REG 250kHz LOGIC OSC 5:1 FREQUENCY SHIFT COMP CURRENT AMP LT1373 with pin low. C compensation network C SW ANTI-SAT DRIVER SWITCH + 0.08 – GND LT1373 • ...
Page 6
... The error amplifier is a current output (g be externally clamped for lowering current limit. Like- wise, a capacitor coupled external clamp will provide soft start. Switch duty cycle goes to zero if the V below the control pin threshold, placing the LT1373 in an idle mode from the ...
Page 7
... When both the FB and NFB pins are used, the LT1373 acts to prevent either output from going beyond its set output voltage. For example in this applica- tion, if the positive output were more heavily loaded than the negative, the negative output would be greater and would regulate at the desired set-point voltage ...
Page 8
... To get low ESR takes volume , so physically smaller capacitors have high ESR. The ESR range for typical LT1373 applications is 0. typical output capacitor is an AVX type TPS 25V, with a guaranteed ESR less than 0.2 . This is a “D” size surface mount solid tantalum capacitor ...
Page 9
... V pin. V pin ripple is caused by output voltage ripple C attenuated by the output divider and multiplied by the error amplifier. Without the second capacitor Pin Ripple = C LT1373 pin) with a series R network. The C C pin ripple is: C 1.245(V )(g )(R ...
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... FREQUENCY CIRCULATING PATH Figure 302. MBRS140T3 4.75V TO 13V T1 • P6KE-20A 2 5 1N4148 4 • S/S SW • LT1373 3 1 NFB MBRS140T3 V GND 0. *DALE LPE-4841-100MB (605) 665-9301 V OUT LOAD LT1373 • F03 , to assist in V OUT 15V + –V OUT –15V R4 12. 2.49k 1% LT1373 • TA04 ...
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... BSC TYP V OUT –3V 250mA 0 16V R2 5.49k 1% LT1373 • TA05 0.400* (10.160) MAX 0.255 0.015* (6.477 0.381 1098 0.189 – 0.197* (4.801 – 5.004 0.150 – 0.157** 0.228 – 0.244 (3.810 – ...
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... R2 LT1373 L1B 2 75k GND 24. 0.01 F † MAX I OUT I V OUT IN 0.45A 4V 0.55A 5V 0.65A 7V 0.72A 9V INDUCTOR WITH TWO WINDINGS as Low as 1.5V IN sn1373 1373fbs LT/TP 0200 2K REV B • PRINTED IN THE USA LINEAR TECHNOLOGY CORPORATION 1995 † V OUT 100 F 10V LT1373 • TA07 ...