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UC1823A, UC2823A, UC2823B,
UC3823A, UC3823B, UC1825A,
UC2825A, UC2825B, UC3825A, UC3825B
SLUS334C − AUGUST 1995 − REVISED AUGUST 2004
HIGH SPEED PWM CONTROLLER
FEATURES
D
Improved Versions of the UC3823/UC3825
D
D
D
D
PWMs
Compatible with Voltage-Mode or
Current-Mode Control Methods
Practical Operation at Switching Frequencies
to 1 MHz
50-ns Propagation Delay to Output
High-Current Dual Totem Pole Outputs
(2-A Peak)
Trimmed Oscillator Discharge Current
DESCRIPTION
The UC3823A and UC3823B and the UC3825A and
UC3825B family of PWM controllers are improved
versions of the standard UC3823 and UC3825 family.
Performance enhancements have been made to several
of the circuit blocks. Error amplifier gain bandwidth product
is 12 MHz, while input offset voltage is 2 mV. Current limit
threshold is assured to a tolerance of 5%. Oscillator
discharge current is specified at 10 mA for accurate dead
time control. Frequency accuracy is improved to 6%.
Startup supply current, typically 100
µA,
is ideal for off-line
applications. The output drivers are redesigned to actively
sink current during UVLO at no expense to the startup
current specification. In addition each output is capable of
2-A peak currents during transitions.
D
D
Low 100-µA Startup Current
D
Pulse-by-Pulse Current Limiting Comparator
D
Latched Overcurrent Comparator With Full
Cycle Restart
BLOCK DIAGRAM
CLK/LEB 4
RT 5
OSC
CT 6
RAMP 7
EAOUT 3
NI
2
E/A
INV 1
1.25 V
(60%)
*
R
SD
PWM
LATCH
T
13 VC
11 OUTA
14 OUTB
12 PGND
9
mA
PWM COMPARATOR
SOFT−START COMPLETE
SS 8
ILIM 9
1.2 V
0.2 V
VCC 15
”B” 16V/10V
”A” 9.2V/8.4V
GND 10
RESTART
DELAY
CURRENT
LIMIT
1.0 V
OVER CURRENT
SD
R
FAULT LATCH
UVLO
VREF
5.1 V
ON/OFF
INTERNAL
BIAS
VREF GOOD
16 5.1 VREF
UDG−02091
5V
RESTART
DELAY
LATCH
S
R
250
mA
4V
* On the UC1823A version, toggles Q and Q are always low.
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. Products
conform to specifications per the terms of Texas Instruments standard warranty.
Production processing does not necessarily include testing of all parameters.
Copyright
2004, Texas Instruments Incorporated
TI [ TEXAS INSTRUMENTS ]
