ꢀꢁꢂ ꢃ ꢄ ꢅ ꢆꢇ ꢀꢁꢄ ꢃ ꢄ ꢅ ꢆꢇ ꢀ ꢁꢄ ꢃꢄ ꢅꢈ ꢇ
ꢀꢁꢅ ꢃ ꢄ ꢅ ꢆꢇ ꢀꢁꢅ ꢃ ꢄ ꢅ ꢈꢇ ꢀ ꢁꢂ ꢃꢄ ꢉꢆ ꢇ
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SLUS334C − AUGUST 1995 − REVISED AUGUST 2004
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FEATURES
DESCRIPTION
D
D
D
Improved Versions of the UC3823/UC3825
PWMs
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.
Compatible with Voltage-Mode or
Current-Mode Control Methods
Practical Operation at Switching Frequencies
to 1 MHz
D
50-ns Propagation Delay to Output
D
High-Current Dual Totem Pole Outputs
(2-A Peak)
D
D
D
D
Trimmed Oscillator Discharge Current
Low 100-µA Startup Current
Pulse-by-Pulse Current Limiting Comparator
Latched Overcurrent Comparator With Full
Cycle Restart
BLOCK DIAGRAM
CLK/LEB 4
(60%)
13 VC
RT
CT
5
6
7
3
2
1
11 OUTA
*
OSC
R
S
T
RAMP
EAOUT
NI
D
1.25 V
E/A
14 OUTB
12 PGND
PWM
LATCH
PWM COMPARATOR
9 mA
INV
SOFT−START COMPLETE
RESTART
CURRENT
LIMIT
5 V
250mA
DELAY
LATCH
SS
8
1.0 V
1.2 V
0.2 V
OVER CURRENT
ILIM 9
S
R
S
D
RESTART
DELAY
R
FAULT LATCH
UVLO
VCC 15
GND 10
”B” 16V/10V
”A” 9.2V/8.4V
INTERNAL
BIAS
VREF
5.1 V
ON/OFF
4 V
V
GOOD
REF
16 5.1 VREF
UDG−02091
* 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.
ꢏꢗ ꢔ ꢑꢀ ꢁ ꢖꢋ ꢔꢕ ꢑ ꢆꢖꢆ ꢙꢚ ꢛꢜ ꢝ ꢞꢟ ꢠꢙꢜꢚ ꢙꢡ ꢢꢣ ꢝ ꢝ ꢤꢚꢠ ꢟꢡ ꢜꢛ ꢥꢣꢦ ꢧꢙꢢ ꢟꢠꢙ ꢜꢚ ꢨꢟ ꢠꢤꢩ ꢏꢝ ꢜꢨꢣ ꢢꢠꢡ
ꢢ ꢜꢚ ꢛꢜꢝ ꢞ ꢠꢜ ꢡ ꢥꢤ ꢢ ꢙ ꢛꢙ ꢢ ꢟ ꢠꢙ ꢜꢚꢡ ꢥ ꢤꢝ ꢠꢪꢤ ꢠꢤ ꢝ ꢞꢡ ꢜꢛ ꢖꢤꢫ ꢟꢡ ꢋꢚꢡ ꢠꢝ ꢣꢞ ꢤꢚꢠ ꢡ ꢡꢠ ꢟꢚꢨ ꢟꢝ ꢨ ꢬ ꢟꢝ ꢝ ꢟ ꢚꢠꢭꢩ
ꢏꢝ ꢜ ꢨꢣꢢ ꢠ ꢙꢜ ꢚ ꢥꢝ ꢜ ꢢ ꢤ ꢡ ꢡ ꢙꢚ ꢮ ꢨꢜ ꢤ ꢡ ꢚꢜꢠ ꢚꢤ ꢢꢤ ꢡꢡ ꢟꢝ ꢙꢧ ꢭ ꢙꢚꢢ ꢧꢣꢨ ꢤ ꢠꢤ ꢡꢠꢙ ꢚꢮ ꢜꢛ ꢟꢧ ꢧ ꢥꢟ ꢝ ꢟꢞ ꢤꢠꢤ ꢝ ꢡꢩ
Copyright 2004, Texas Instruments Incorporated
TI [ TEXAS INSTRUMENTS ]
