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FEATURES
DESCRIPTION
www.ti.com............................................................................................................................................................................................... SLUS874 – JANUARY 2009
RAD-TOLERANT CLASS-V REGULATING PULSE WIDTH MODULATOR
QML-V Qualified, SMD 5962-89511
Rad-Tolerant: 30 kRad (Si) TID (1)
The UC1525B pulse width modulator integrated
circuit is designed to offer improved performance and
8-V to 35-V Operation
lowered external parts count when used in designing
5.1-V Buried Zener Reference Trimmed to
all types of switching power supplies. The on-chip
±0.75%
5.1-V buried zener reference is trimmed to ±0.75%,
100-Hz to 400-kHz Oscillator Range
and the input common-mode range of the error
amplifier includes the reference voltage, eliminating
Separate Oscillator Sync Terminal
external resistors. A sync input to the oscillator allows
Adjustable Deadtime Control
multiple units to be slaved or a single unit to be
Internal Soft Start
synchronized to an external system clock. A single
resistor between the CT and the discharge terminals
Pulse-by-Pulse Shutdown
provide a wide range of dead-time adjustment. These
Input Undervoltage Lockout With Hysteresis
devices also feature built-in soft-start circuitry with
Latching PWM to Prevent Multiple Pulses
only
an
external
timing
capacitor
required.
A
shutdown terminal controls both the soft-start circuitry
Dual Source/Sink Output Drivers
and the output stages, providing instantaneous turn
Low Cross Conduction Output Stage
off through the PWM latch with pulsed shutdown, as
Tighter Reference Specifications
well as soft-start recycle with longer shutdown
commands. These functions are also controlled by an
undervoltage lockout which keeps the outputs off and
the soft-start capacitor discharged for sub-normal
input
voltages.
This
lockout
circuitry
includes
approximately 500 mV of hysteresis for jitter-free
operation. Another feature of these PWM circuits is a
latch following the comparator. Once a PWM pulse
has been terminated for any reason, the outputs
remain off for the duration of the period. The latch is
reset with each clock pulse. The output stages are
totem-pole designs capable of sourcing or sinking in
excess of 200 mA. The UC1525B output stage
(1)
Radiation tolerance is a typical value based upon initial device
features NOR logic, giving a LOW output for an OFF
qualification with dose rate = 10 mrad/sec. Radiation Lot
Acceptance Testing is available - contact factory for details.
state.
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Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
PRODUCTION DATA information is current as of publication date.
Copyright 2009, Texas Instruments Incorporated
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.