CS51021/CS51023
CS51022/CS51024
Enhanced Current Mode
PWM Controller
Description
Features
The CS51021/ 22/ 23/ 24 Fixed
Frequency PWM Current Mode
Controller family provides all neces- ing, current slope compensation,
sary features required for AC-DC or accurate duty cycle control and an
threshold overcurrent protection,
current sense leading edge blank-
ꢀ 75µA Max. Startup Current
ꢀ Fixed Frequency Current
Mode Control
DC-DC primary side control.
Several features are included elimi-
nating the additional components
externally available 5V reference.
The CS51021 and CS51023 feature
bidirectional synchronization capa-
ꢀ 1MHz Switching Frequency
ꢀ Undervoltage Protection
Monitor
needed to implement them external- bility, while the CS51022 and
ꢀ Overvoltage Protection
Monitor with
ly. In addition to low start-up cur-
rent (75µA) and high frequency
operation capability, the CS51021/
22/ 23/ 24 family includes overvolt-
age and undervoltage monitoring,
externally programmable dual
CS51024 offer a sleep mode with
100µA maximum IC current con-
sumption. The CS51021/ 22/ 23/ 24
family is available in a 16 lead nar-
row body SO package.
Programmable Hysteresis
ꢀ Programmable Dual
Threshold Overcurrent
Protection with Delayed
Restart
ꢀ Programmable Soft Start
Device
Sleep/Synch
VCC Start/Stop
8.25V/ 7.7V
8.25V/ 7.7V
13V/ 7.7V
ꢀ Accurate Maximum Duty
Cycle Limit
CS51021
CS51022
CS51023
CS51024
Synch
Sleep
Synch
Sleep
ꢀ Programmable Slope
Compensation
ꢀ Leading Edge Current
13V/ 7.7V
Sense Blanking
ꢀ 1A Sink/Source Gate Drive
ꢀ Bidirectional Synchronization
(CS51021/23)
Typical Application Diagram
100
V
IN
(36V to 72V)
ꢀ 50ns PWM Propagation
PGND
BAS21
1µF
51k
Delay
18V
SYNC/SLEEP
22µF
ꢀ 100µA Max Sleep Current
11V
100:1
10K
0.1µF
FZT688
2:5
MBRB2060CT
200K,1%
4:1
(CS51022/24)
10
24.3K
1%
V
OUT
(5V/5A)
10
VC
VREF
VCC
UV
0.01µF
4700pF
51K
2.49K,1%
BA521
22K
10K
100µF
100µF
680pF
COMP
Package Options
OV
SGND
100pF
VFB
ISET
RTCT
16 Lead SO Narrow & PDIP
SLOPE
GATE
ISENSE
IRF6345
10
SYNC/
SLEEP
CSS
6.98k,
1%
1
6.98k,
1%
100
100p
330pF
PGnd
V
C
GATE
SENSE
LGnd U1
10
62
0.01µF
470pF
I
PGnd
SLEEP
or SYNC
SLOPE
V
V
CC
0.1µF
5.1K
REF
TL431
1K
2K, 1%
1000pF
LGnd
SS
UV
OV
180
2K,1%
10K
R C
COMP
T
T
MOC81025
I
SET
V
1K
FB
Consult factory for other package options.
36-72V to 5V, 5A DC-DC Convertor
ON Semiconductor
2000 South County Trail, East Greenwich, RI 02818
Tel: (401)885–3600 Fax: (401)885–5786
N. American Technical Support: 800-282-9855
Web Site: www.onsemi.com
September, 2000 - Rev. 13
1