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FAN7556
Features
* * * * * * * * * * * * * *
Voltage Mode PWM Controller
Description
The FAN7556 is a fixed frequency voltage mode PWM controller. It is specially designed for off-line and DC-DC converter applications with minimal external components. These integrated circuits feature a trimmed oscillator for precise duty cycle control, a temperature compensated reference, an on/off control, a high gain error amplifier, a current sensing comparator, and a high current totem-pole output. The FAN7556 has various protection functions such as an over load protection (OLP), an over current protection(OCP), and an over voltage protection(OVP). The FAN7556 is available in the 8DIP package as well as the 8SOP package.
8-DIP
Voltage Mode Control Pulse by Pulse Current Limiting Low External Components Under Voltage Lockout ( UVLO): 9V/15V Stand-by Current: Typ. 100uA Power Saving Mode Current: Typ. 200uA Operating Current: Typ. 7mA Soft Start On/off Control Over Load Protection (OLP) Over Current Protection (OCP) Over Voltage Protection (OVP) Wide Operating Frequency Range (20kHz ~ 500kHz) Auto-Restart Function
Applications
* Off-Line & DC-DC Converter
1
8-SOP
1
Internal Block Diagram
CT Vcc 6
+ + 34V + _ + + _ _ _ 15/9V CLK OSC 14V PWM OVP + _ 1k 0.3V + 1.5V 1mA 3k Vref Vcc 5uA OLP COM-out OVP-out UVLO-out + + S R Q _ 6V + _ S Q R off PWR / SAVE Vref
7 4
COM
LA
1
2V Vref
3.5V
100uA
S/S
8
2.7V Q R S
(c)2002 Fairchild Semiconductor Corporation
_ _ _
FB
2
+ +
_ _ _
+ +
UVLO
on
5
OUT
OCP
3
0.25V
IS
4
GND
Rev. 1.0.1
FAN7556
Absolute Maximum Ratings
( Ta = 25C, unless otherwise specified ) Parameter Supply Voltage Output Current Input Voltage to FB Pin Input Voltage to IS Pin Power Dissipation (Ta 25C) 8-DIP 8-SOP Operating Temperature Storage Temperature Thermal Resistance, Junction-to-Air(Note1) 8-DIP 8-SOP
Note: 1. Junction -to -air thermal resistance test environments. -. Pneumatic heat sink fixture. -. Clamping pressure 60psi through 12mm diameter cylinder. -. Thermal grease applied between PKG and heat sink fixture
Symbol Vcc IO VFB VIS PD TOPR TSTG Rja
Value 30 1 VSD -0.3 to VOC 0.85 0.62 -25 to +125 -55 to +150 147.1 201.6
Unit V A V V W C C C/W
Temperature Characteristics
( -25C Ta 125C ) Parameter Fosc Temperature Stability Symbol FOSC2 Value 5 Unit %
2
FAN7556
PIN Array
S/S 8
CT 7
Vcc 6
OUT 5
YWW FAN7556
1 LA 2 FB 3 IS 4 GND
YWW : Work Week Code
PIN Definitions
Pin Number 1 2 3 4 5 6 7 8 Pin Name LA FB IS GND OUT Vcc CT S/S Optional Protection Inverting (-) Input of PWM Comparator, ON/OFF Control & Over Load Sensing Over Current Sensing Ground Output of Gate Driver Power Supply Oscillator Timing Capacitor Ct Soft Start Pin Function Description
3
FAN7556
Electrical Characteristics
(Ta = 25C, Vcc=18V, Ct=1nF unless otherwise specified) Parameter < OSCILLATOR SECTION > Oscillator Frequency Frequency Change With Vcc Temperature Stability (Note1) < PWM SECTION > FB Source Current FB Threshold Voltage 1 FB Threshold Voltage 2 Maximum Duty Cycle < SOFT START SECTION > Soft Start Current Soft Start Limit Voltage < PROTECTION SECTION > Shutdown Feedback Voltage Shutdown Delay Current Over Current Protection Over Voltage Protection Comparator Threshold Voltage Start Threshold Voltage Min. Operating Voltage < ON/OFF CONTROL SECTION > On Threshold Voltage Off Threshold Voltage Sink Current Low Output Voltage1 Low Output Voltage2 High Output Voltage1 High Output Voltage2 Rise Time (Note1) Fall Time (Note1) < OVERALL SECTION > Start-Up Current Operating Supply Current Off State Current VST IOP IOFF Vcc 30V VFB < VTH(FB), VS/S < VOFF 0.1 7 0.2 0.2 10 0.4 mA mA mA VOL1 VOL2 VOH1 VOH2 TR TF Io = 50mA Io = 200mA Io = -50mA IO = -200mA CL= 1nF, (No load) CL= 1nF, (No load) 13 12 0.15 1.5 15 14 80 40 0.4 2.5 17 16 V V V V ns ns VON VOFF ISINK VIS = 0V VFB < VON VFB < VTH(FB), VS/S = 5V 0.2 1.2 3 0.3 1.5 4 0.4 1.8 5 V V mA VTH(ST) VOPR(MIN) 13.2 8.2 14.7 9.2 16.2 10.2 V V VSD ISD VOC VOVP VLA VFB > 5V 4V VFB VSD VFB = 3V, VS/S = 5V 5.4 3.5 0.22 30 1.7 6 5 0.26 34 2 6.6 6.5 0.29 38 2.3 V uA V V V IS/S VLIM(S/S) VFB = 5V, VS/S = 0V 1.1 5.2 mA V IFB VTH(FBO) VTH(FBM) DMAX VFB = 0V, VS/S = 5V Duty = 0% Duty = DMAX 70 1.0 0.85 2.7 74 78 mA V V % FOSC FOSC1 FOSC2 Tj =25C, Ct=1nF Vcc=10V~30V -25C Ta 125C 90 100 1 5 110 kHz % % Symbol Conditions Min. Typ. Max. Unit
Note: 1. These parameters, although guaranteed, are not 100% tested in production.
4
FAN7556
Typical Performance Characteristics
Figure 1. Operating Current vs. Ambient Temperature
Figure 2. Frequency vs. Ambient Temperature
Figure 3. Output Duty Cycle vs. Ambient Temperature
Figure 4. Output Duty Cycle vs. Timing Capacitor
Figure 5. Output Duty Cycle vs. Frequency
Figure 6. Frequency vs. Timing Capacitor
5
FAN7556
Typical Performance Characteristics (Continued)
Figure 7. Output Duty Cycle vs. FB Terminal Voltage
6
FAN7556
Mechanical Dimensions
Package Dimensions in millimeters
8-DIP
7
FAN7556
Mechanical Dimensions (Continued)
Package Dimensions in millimeters
8-SOP
MIN 1.55 0.20 0.061 0.008 0.1~0.25 0.004~0.001
#1
#8 4.92 0.20 0.194 0.008 5.13 MAX 0.202
( #4 #5 6.00 0.30 0.236 0.012
+0.10 0.15 -0.05 +0.004 0.006 -0.002
0.56 ) 0.022 1.80 MAX 0.071 MAX0.10 MAX0.004 3.95 0.20 0.156 0.008 5.72 0.225 0.50 0.20 0.020 0.008
8
0~
8
1.27 0.050
0.41 0.10 0.016 0.004
FAN7556
Ordering Information
Product Number FAN7556N FAN7556M FAN7556MX Package 8-DIP 8-SOP 8-SOP -25C ~ 125C Operating Temperature Packing Tube Tube Tape&Reel
9
FAN7556
DISCLAIMER FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. FAIRCHILD DOES NOT ASSUME ANY LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN; NEITHER DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS. LIFE SUPPORT POLICY FAIRCHILD'S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and (c) whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury of the user.
www.fairchildsemi.com 11/12/02 0.0m 001 Stock#DSxxxxxxxx 2002 Fairchild Semiconductor Corporation
2. A critical component in any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness.

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