CS51021/22/23/24
CS51021/CS51023
CS51022/CS51024
Enhanced Current Mode
PWM Controller
Description
The CS51021/22/23/24 Fixed
Frequency PWM Current Mode
Controller family provides all neces-
sary features required for AC-DC or
DC-DC primary side control.
Several features are included elimi-
nating the additional components
needed to implement them external-
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
Device
Features
s
75µA Max. Startup Current
s
Fixed Frequency Current
Mode Control
s
1MHz Switching Frequency
s
Undervoltage Protection
Monitor
s
Overvoltage Protection
Monitor with
Programmable Hysteresis
s
Programmable Dual
Threshold Overcurrent
Protection with Delayed
Restart
s
Programmable Soft Start
s
Accurate Maximum Duty
Cycle Limit
s
Programmable Slope
Compensation
s
Leading Edge Current
Sense Blanking
s
1A Sink/Source Gate Drive
s
Bidirectional Synchronization
(CS51021/23)
s
50ns PWM Propagation
Delay
s
100µA Max Sleep Current
(CS51022/24)
threshold overcurrent protection,
current sense leading edge blank-
ing, current slope compensation,
accurate duty cycle control and an
externally available 5V reference.
The CS51021 and CS51023 feature
bidirectional synchronization capa-
bility, while the CS51022 and
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.
Sleep/Synch
V
CC
Start/Stop
CS51021
CS51022
CS51023
CS51024
Synch
Sleep
Synch
Sleep
Typical Application Diagram
8.25V/7.7V
8.25V/7.7V
13V/7.7V
13V/7.7V
V
IN
(36V to 72V)
PGND
SYNC/SLEEP
100
51k
11V
FZT688
10
BAS21
22µF
18V
0.1µF
1µF
100:1
200K,1%
24.3K
1%
10K
4:1
MBRB2060CT
2:5
V
OUT
(5V/5A)
100µF 100µF
SGND
0.01µF
10K
4700pF
51K
CS51021/51022
22K
V
C
V
REF
COMP
V
FB
R
T
C
T
SYNC/
SLEEP
C
SS
LGnd
V
CC
UV
OV
I
SET
SLOPE
GATE
I
SENSE
PGnd
10
2.49K,1%
680pF
BA521
10
IRF6345
100pF
Package Options
16 Lead SO Narrow
GATE
I
SENSE
SLEEP
or SYNC
SLOPE
1
330pF
0.01µF
U1
6.98k, 6.98k,
100
1%
1%
100p
470pF
62
10
V
C
PGnd
V
CC
V
REF
LGnd
SS
COMP
V
FB
0.1µF 5.1K
TL431
1000pF
180
10K
MOC81025
2K, 1%
UV
OV
R
T
C
T
I
SET
1K
2K,1%
1K
36-72V to 5V, 5A DC-DC Convertor
Consult factory for other package options.
Cherry Semiconductor Corporation
2000 South County Trail, East Greenwich, RI 02818
Tel: (401)885-3600 Fax: (401)885-5786
Email: info@cherry-semi.com
Web Site: www.cherry-semi.com
Rev. 2/22/99
1
A
®
Company
CHERRY [ CHERRY SEMICONDUCTOR CORPORATION ]
