SLVS141A Datasheet, PDF (5/18 Pages) Texas Instruments – FIXED NEGATIVE 5-V 200-mA INVERTING DC/DC CONVERTER

TPS6735
FIXED NEGATIVE 5ĆV 200ĆmA INVERTING DC/DC CONVERTER
SLVS141A − JULY 1996 − REVISED JANUARY 1997
SS clamp
The SS clamp circuit limits the signal level on error-amplifier output during start-up. The voltage on SS is
amplified and used to override the error-amplifier output until it rises above that output, at which point the error
amplifier takes over. This prevents the input to the PWM comparator from exceeding its common-mode range
(i.e., error amplifier output too high to be reached by the current ramp) by limiting the maximum voltage on the
error-amplifier output during start-up.
Soft start causes the output voltage to increase to the regulation point at the controlled rate. The voltage on the
charging soft-start capacitor gradually raises the clamp on the error amplifier output voltage, limiting surge
currents at power up by increasing the current limit threshold on a cycle-by-cycle basis. A soft-start cycle is
initiated when either the enable (EN) signal is switched high or an overcurrent fault condition triggers the
discharge of the soft-start capacitor.
undervoltage lockout (UVLO)
The supply voltage is fed through a voltage divider to the input of the UVLO and compared to a reference. The
undervoltage-lockout logic prevents the MOSFET from turning on while the supply voltage is below the
undervoltage-lockout voltage threshold, and once the supply voltage on V_CC is above the threshold, an SS cycle
is initiated.
PACKAGE
D
P
TA ≤ 25°C
POWER RATING
725 mW
1175 mW
DISSIPATION RATING TABLE
DERATING FACTOR
ABOVE TA = 25°C
5.8 mW/°C
TA = 70°C
POWER RATING
464 mW
9.4 mW/°C
752 mW
TA = 85°C
POWER RATING
377 mW
611 mW
absolute maximum ratings over operating free-air temperature range (unless otherwise noted)^†
Pin voltages:
V_CC (see Note 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −0.3 V to 7 V
OUT to V_CC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.5 V
FB (see Note 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 V
SS, COMP, EN voltage range (see Note 1) . . . . . . . . . . . . . . . . . . . . −0.3 V to V_CC +0.3 V
Peak switch current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 A
Reference current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5 mA
Continuous total power dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . See Dissipation Rating Table
Operating free-air temperature range, T_A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −40°C to 85°C
Storage temperature range, T_stg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −65°C to 150°C
Lead temperature 1,6mm (1/16 inch) from case for 10 s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260°C
† _{Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and}
functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not
implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
NOTE 1: All voltage values are with respect to network terminal ground.
recommended operating conditions
Supply voltage
Decoupling capacitor
Input capacitor
Reference capacitor
Output capacitor
Compensation capacitor
Inductor
MIN NOM MAX UNIT
4
6.2 V
1
µF
47
µF
10
µF
100
µF
82
pF
10
µH
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