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Part: ISL6721AB-T
Category:
Power Management
-> PWM Controllers
Description: Single-ended Current Mode PWM Controller With Synchronize & Advanced Fault Protection Features
Company: Intersil Corporation
Datasheet: Download ISL6721AB-T datasheet File size : 330 kB
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Datasheet text preview:
®
ISL6721
D a ta Sheet A u g us t 2003 FN9110.1
Flexible Single Ended Current Mode PWM Controller
The ISL6721 is a low power, single-ended pulse width modulating (PWM) current mode controller designed for a wide range of DC-DC conversion applications including boost, flyback, and isolated output configurations. Peak current mode control effectively handles power transients and provides inherent over-current protection. Other features include a low power mode where the supply current drops to less than 200µA during over voltage and over current shutdown faults. This advanced BiCMOS design features low operating current, adjustable operating frequency up to 1MHz, adjustable soft-start, and a bi-directional SYNC signal that allows the oscillator to be locked to an external clock for noise sensitive applications.
Features
· 1A MOSFET Gate Driver · 100µA Startup Current · Fast Transient Response with Peak Current Mode Control · Adjustable Switching Frequency up to 1MHz · Bi-Directional Synchronization · Low Power Disable Mode · Delayed Restart from OV and OC Shutdown Faults · Adjustable Slope Compensation · Adjustable Soft Start · Adjustable Over Current Shutdown Delay · Adjustable UV and OV Monitors · Leading Edge Blanking · Integrated Thermal Shutdown
Ordering Information
PART NUMBER ISL6721AB ISL6721AV TEMP. RANGE (oC) -40 to 105 -40 to 105 PA CKAGE 16 Ld SOIC 16 Ld TSSOP PKG. DWG. # M16.15 M 16.173
· 1% Tolerance voltage Reference
Applications
· Telecom and Datacom Power · Wireless Base Station Power · File Server Power · Industrial Power Systems · Isolated Buck and Flyback Regulators · Boost Regulators
Pinout
ISL6721 (SOIC, TSSOP) TOP VIEW
G A TE 1 ISENSE 2 SYNC 3 SLOPE 4 UV 5 OV 6 R TC T 7 ISET 8 16 VC 15 PGND 14 VCC 13 VREF 12 LGND 11 SS 10 COMP 9 FB
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. 1-888-INTERSIL or 321-724-7143 | Intersil (and design) is a registered trademark of Intersil Americas Inc. Copyright © Intersil Americas Inc. 2003. All Rights Reserved. All other trademarks mentioned are the property of their respective owners.
ISL6721 Functional Block Diagram
VCC START/STOP UV COMPARATOR + BG + LGND THERMAL PROTECTION RESTART DELAY ISET 0.8 ISENSE 5K VREF 53 µA + + 100mV + + OVERCURRENT COMPARATOR
Q Q
VREF 5.00 V 1% ENABLE
VREF SOFTSTART CHARGE 70 µA CURRENT ON
SS CHARGE VOLTAGE CLAMP
SS OVERCURRENT SHUTDOWN DELAY 25 µA + + 15 µA
SS CHARGED
4.375V ON
OC DETECT
S R
Q Q
OC LATCH 50 µS RETRIGGERABLE ONE SHOT
SLOPE 0.1
SS LOW
+ + -
SS COMP + -
FAULT LATCH SS CLAMP
S R Q Q
270mV SS LOW COMPARATOR
PW M COMPARATOR 2.5V VFB ERROR AMPLIFIER + 1/3 100nS BLANKING START + + VREF 20K 3.0V 1.5V
SET DOMINANT VREF UV COMPARATOR 4.65V + + BG
VREF
+ 12K ON BLANKING COMPARATOR + OSCILLATOR COMPARATOR + 3.0V + -
OV 2.50V UV 1.45V + + -
30K
S
Q Q
VC
RTCT 1mA VREF ON
+
Bi-Directional Synchronization
OSC IN CLK OUT
R
GATE
36K
4V
+ -
NO EXT SYNC
2V
+
EXT SYNC BLANKING SYNC IN VREF SYNC OUT
PGND
100 SYNC 4.5K
2
ISL6721 Typical Application - 48V Input Dual Output Flyback, 3.3V @ 2.5A, 1.8V @ 1.0A
SP1 SP2
CR5 T1 IS O L A T IO N XFMR V IN + P 9 R21 + 3 .3 V C21 + C15 + C16
R24
C18 CR4 C19 + C22 + C20
+ 1 .8 V
C2 C5
CR2
C17
RET URN CR6 R1 3 6 -7 5 V C6 C1 C3 TP1 Q1 R2 U2 C14 R16 R17 R18 R19
R4 R23
R3
R22 U3 TP2
R15 C13
V IN -
R20
R25 Q2 D1 TP3 SYNC C4 G AT E IS E N S E SYNC U4 VC PGND VCC
ISL6721
SLOPE UV R5 R6 D2 TP5 OV RTCT IS E T
VREF LGND SS COMP VFB R27 R26
R14
TP4
Q3
C12 R8 R10 C7 R7 R9
C11 C9
VR1
C8 R11 R12 R13
C10
3
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