1
FEATURES
DESCRIPTION
4
5
6
7
3
2
1
8
9
15
10
16
12
14
11
13
CLOCK
RT
CT
RAMP
E/A Out
NI
INV
Error
Amp
Soft Start
ILIM / SD
VCC
GND
VREF
Pwr GND
Out B
Out A
Vc
OSC
PWM Latch
(Set Dom.)
R
S
1.25 V
Wide Bandwidth
Error Amp.
+
Inhibit
ILIM
CPRTR
1 V
1.4 V
9 V
Shutdown
CPRTR
UVLO
VCC Good
Gate
REF
Gen
Internal
Bias
4 V
VREF Good
Output
Inhibit
T
9
A
VIN
Toggler F/F
VDG920322
www.ti.com............................................................................................................................................................................................... SLUS870 – JANUARY 2009
RAD-TOLERANT CLASS V, HIGH-SPEED PWM CONTROLLER
QML-V Qualified, SMD 5962-87681
Rad-Tolerant: 30 kRad (Si) TID (1)
The UC1825 PWM control device is optimized for
high-frequency
switched
mode
power
supply
Compatible With Voltage- or Current-Mode
applications. Particular care was given to minimizing
Topologies
propagation delays through the comparators and
Practical Operation Switching Frequencies to
logic circuitry while maximizing bandwidth and slew
1 MHz
rate of the error amplifier. This controller is designed
for use in either current-mode or voltage mode
50-ns Propagation Delay-to-Output
systems
with
the
capability
for
input
voltage
High-Current Dual Totem Pole Outputs
feed-forward.
(1.5 A Peak)
Protection circuitry includes a current limit comparator
Wide Bandwidth Error Amplifier
with a 1-V threshold, a TTL compatible shutdown
Fully Latched Logic With Double-Pulse
port, and a soft start pin which will double as a
Suppression
maximum duty-cycle clamp. The logic is fully latched
Pulse-by-Pulse Current Limiting
to provide jitter-free operation and prohibit multiple
pulses at an output. An undervoltage lockout section
Soft Start/Maximum Duty-Cycle Control
with 800 mV of hysteresis assures low start up
Undervoltage Lockout With Hysteresis
current. During undervoltage lockout, the outputs are
Low Start-Up Current (1.1 mA)
high impedance.
This device features totem pole outputs designed to
source and sink high peak currents from capacitive
(1)
Radiation tolerance is a typical value based upon initial device
loads, such as the gate of a power MOSFET. The on
qualification with dose rate = 10 mrad/sec. Radiation Lot
Acceptance Testing is available - contact factory for details.
state is designed as a high level.
BLOCK DIAGRAM
1
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas
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.