Cherry Semiconductor CS51221EN16, CS51221EDR16, CS51221ED16 Datasheet
Features
■ 1MHz Frequency Capability
■ Fixed Frequency Voltage
Mode Operation, with Feed
Forward
■ Thermal Shutdown
■ Under Voltage Lock-out
■ Accurate Programmable Max
Duty Cycle Limit
■ 1A Sink/Source Gate Drive
■ Programmable Pulse by
Pulse Over Current
Protection
■ Leading Edge Current Sense
Blanking
■ 75ns Shutdown Propagation
Delay
■ Programmable Soft Start
■ Under Voltage Protection
■ Over Voltage Protection with
Programmable Hysteresis
■ Bidirectional
Synchronization
■ 25ns GATE Rise and Fall
Time (1nF load)
■ 3.3V 3% Reference Voltage
Output
Package Options
CS51221
Enhanced Voltage Mode PWM Controller
CS51221
Description
Application Diagram
GATE
I
SENSE
SYNC
FF
UV
OV
R
TCT
I
SET
VC
PGnd
V
CC
LGnd
SS
COMP
V
FB
V
REF
16 Lead SO Narrow & PDIP
1
36V-72V to 5V/5A converter
Rev. 3/26/99
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
A Company
®
The CS51221 fixed frequency
feed forward voltage mode
PWM controller contains all of
the features necessary for basic
voltage mode operation. This
PWM controller has been optimized for high frequency primary side control operation. In
addition, this device includes
such features as: Soft Start, accurate duty cycle limit control, less
than 50µA startup current, over
and under voltage protection,
and bidirectional synchronization. The CS51221 is available in
16 lead PDIP and SO narrow
surface mount packages.
V
IN
(36V to 72V)
51k
0.01µF
470pF
20.25k
10
13k
510k
0.1µF
62
IRF634
100
1µF
10
680pF
150
1k
180
MOC81025
2k
100µF
SGnd
V
OUT
(5V/5A)
2200pF
5.1k
0.1µF
SYNC
4.3k
200
10k
1µF
2k
1k
330pF
MBRB2545CT
100pF
10
D11
BAS21
10k
BAS21
18V
22µF
11V
FZT688
10
0.22µF
24.3k
TL431
T1
4:1
T3
100:1
T2
2:5
UV
U1
OV
V
REF
RT/C
T
I
SET
LGnd
SS
V
FB
COMP
SYNC
PGnd
FF
V
C
V
CC
I
SENSE
CS51221/2
GATE
160k
5.6k
D13
V33MLA1206A23
4700pF
1
CS51221
Operating Junction Temperature, TJ. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Internally Limited
Lead Temperature Soldering:
Wave Solder (through hole styles only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Sec. max 260˚C Peak
Reflow (SMD styles only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 Sec max. above 183˚C, 230˚C Peak
Storage Temperature Range, TS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -65 to 150˚C
ESD (Human Body Model). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2kV
Absolute Maximum Ratings
PIN SYMBOL PIN NAME
V
MAX
V
MIN
I
SOURCE
I
SINK
GATE Gate Drive Output 15V -0.3V 1.0A Peak 1.0A Peak
200mA DC 200mA DC
I
SENSE
Current Sense Input 6V -0.3V 1mA 1mA
R
TCT
Timing Resistor/Capacitor 6V -0.3V 1mA 10mA
FF Feed Forward 6V -0.3V 1mA 25mA
COMP Error Amp Output 6V -0.3V 10mA 20mA
V
FB
Feedback Voltage 6V -0.3V 1mA 1mA
SYNC Sync Input 6V -0.3V 10mA 10mA
UV Under Voltage 6V -0.3V 1mA 1mA
OV Over Voltage 6V -0.3V 1mA 1mA
I
SET
Current Set 6V -0.3V 1mA 1mA
SS Soft Start 6V -0.3V 1mA 10mA
V
CC
Logic Section Supply 15V -0.3V 10mA 50mA
V
C
Power Section Supply 15V -0.3V 10mA 1.0A Peak
200mA DC
V
REF
Reference Voltage 6V -0.3V Internally 10mA
Limited
PGnd Power Ground N/A N/A 1.0A Peak N/A
200mA DC
LGnd Logic Ground N/A N/A N/A N/A
2
CS51221
3
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
Electrical Characteristics: -40˚C < TA< 85˚C; -40˚C < TJ< 125˚C; 3V < VC < 15V; 4.7V < VCC< 15V; Rt=12K, Ct=390pF
Unless otherwise stated.
■ Start/Stop Voltages
Start Threshold 4.4 4.6 4.7 V
Stop Threshold 3.2 3.8 4.1 V
Hysteresis Start - Stop 400 850 1400 mV
I
CC
@ Startup V
CC
< UVL Start Threshold 38 75 µA
■ Supply Current
I
CC
Operating 9.5 14 mA
I
C
Operating 1nF Load on GATE 12 18 mA
I
C
Operating No switching 2 4 mA
■ Reference Voltage
Total Accuracy 0mA < I
REF
< 2mA 3.2 3.3 3.4 V
Line Regulation 6 20 mV
Load Regulation 0mA < I
REF
< 2mA 6 15 mV
Noise Voltage 10Hz < F < 10kHz (Note 1) 50 µV
Op Life Shift T = 1000Hrs. (Note 1) 4 20 mV
Fault Voltage 2.8 2.95 3.1 V
V
REF(OK)
Voltage 2.9 3.05 3.2 V
V
REF(OK)
Hysteresis 30 100 150 mV
Current Limit 2 40 100 mA
■ Error Amp
Reference Voltage V
FB
= COMP 1.234 1.263 1.285 V
V
FB
Input Current VFB= 1.2V 1.3 2 µA
Open Loop Gain (Note 1) 60 dB
Unity Gain Bandwidth (Note 1) 1.5 MHz
COMP Sink Current COMP = 1.4V, V
FB
= 1.45V 3 12 32 mA
COMP Source Current COMP = 1.4V, V
FB
= 1.15V 1 1.6 2.0 mA
COMP High Voltage V
FB
= 1.15V 2.8 3.1 3.4 V
COMP Low Voltage V
FB
= 1.45V 75 125 300 mV
PSRR Freq = 120Hz (Note 1) 60 85 dB
SS Clamp, V
COMP
SS = 1.4V, V
FB
= 0V, I
SET
= 2V 1.3 1.4 1.5 V
COMP Max Clamp Note 1 1.7 1.8 1.9 V
Electrical Characteristics: -40˚C < TA< 85˚C; -40˚C < TJ< 125˚C; 3V < VC < 15V; 4.7V < VCC< 15V; Rt=12K, Ct=390pF
Unless otherwise stated.
CS51221
4
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
■ Oscillator
Frequency Accuracy 260 273 320 kHz
Voltage Stability 1 2 %
Temperature Stability (Note 1) -40˚C < T
J
< 125˚C8%
Max Frequency (Note 1) 1 MHz
Duty Cycle 80 85 90 %
Peak Voltage (Note 1) 1.94 2.00 2.06 V
Valley Clamp Voltage 0.90 0.95 1.00 V
Valley Voltage (Note 1) 0.85 1.00 1.15 V
Discharge Current 0.85 1.00 1.15 mA
■ Synchronization
Input Threshold 0.9 1.4 1.8 V
Output Pulse Width 200 320 450 ns
Output High Voltage 100µA Load 2.1 2.5 2.8 V
Input Resistance 35 70 140 kΩ
SYNC to Drive Delay Time from SYNC to 100 140 180 ns
GATE Shutdown
Output Drive Current R
SYNC
= 1Ω 1.00 1.50 2.25 mA
■ GATE Driver
High Saturation Voltage V
C
-GATE, VC = 10V, 1.5 2.0 V
I
SOURCE
= 200mA
Low Saturation Voltage GATE-PGnd, I
SINK
= 200mA 1.2 1.5 V
High Voltage Clamp 11.0 13.5 16.0 V
Output Current 1 nF load (Note 1) 1 1.25 A
Output UVL Leakage GATE = 0V 1 50 µA
Rise Time 1nF load, V
C
= 20V, 1V < GATE < 9V 60 100 ns
Fall Time 1nF load, V
C
= 20V, 9V < GATE < 1V 25 50 ns
Max Gate Voltage I
GATE
= 500µA .4 .7 1.0 V
during UVL/Sleep
■ FeedForward (FF)
Discharge Voltage I
FF
= 2mA 0.3 0.7 V
Discharge Current FF = 1V 2 16 30 mA
FF to GATE Delay 50 75 125 ns
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