Datasheet

ManualsBrandsST ManualsIntegrated Circuits (ICs)SMPS Controller, SO-8, Tube, 400mA, 18V

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L6565

January 2003

■ QUASI-RESONANT (QR) ZERO-VOLTAGE-

SWITCHING (ZVS) TOPOLOGY

■ LINE FEED FORWARD TO DELIVER

CONSTANT POWER vs. MAINS CHANGE

■ FREQUENCY FOLDBACK FOR OPTIMUM

STANDBY EFFICIENCY

■ PULSE-BY-PULSE & HICCUP-MODE OCP

■ ULTRA-LOW START-UP (< 70µA) AND

QUIESCENT CURRENT (< 3.5mA)

■ DISABLE FUNCTION (ON/OFF CONTROL)

■ 1% PRECISION (@ T

= 25°C) INTERNAL

REFERENCE VOLTAGE

■ ±400mA TOTEM POLE GATE DRIVER WITH

UVLO PULL-DOWN

■ BLUE ANGEL, ENERGY STAR, ENERGY

2000 COMPLIANT

APPLICATIONS

■ TV/MONITOR SMPS

■ AC-DC ADAPTERS/CHARGERS

■ DIGITAL CONSUMER

■ PRINTERS, FAX MACHINES,

PHOTOCOPIERS AND SCANNERS

DESCRIPTION

The L6565 is a current-mode primary controller IC,

specifically designed to build offline Quasi-resonant

ZVS (Zero Voltage Switching at switch turn-on) fly-

back converters.

Quasi-resonant operation is achieved by means of a

transformer demagnetization sensing input that trig-

gers MOSFET's turn-on.

DIP8(Minidip) SO-8

ORDERING NUMBERS:

L6565N L6565D

QUASI-RESONANT SMPS CONTROLLER

BLOCK DIAGRAM

REF2

VOLTAGE

REGULATOR

INTERNAL

SUPPLY

2.5V

DRIVER

ZERO CURRENT

DETECTOR

2.1V

1.6V

VCC8

ZCD

INV

COMP

VFF

GND

20V

40K

5pF

BLANKING

LINE VOLTAGE

FEEDFORWARD

Hiccup-mode

OCP

DISABLE

STARTER

2 V

Hiccup-mode

OCP

Starter

STOP

UVLO

Blanking

START

Summary of content (17 pages)

PAGE 1
L6565 QUASI-RESONANT SMPS CONTROLLER QUASI-RESONANT (QR) ZERO-VOLTAGESWITCHING (ZVS) TOPOLOGY ■ LINE FEED FORWARD TO DELIVER CONSTANT POWER vs. MAINS CHANGE ■ FREQUENCY FOLDBACK FOR OPTIMUM STANDBY EFFICIENCY ■ PULSE-BY-PULSE & HICCUP-MODE OCP ■ ULTRA-LOW START-UP (< 70µA) AND QUIESCENT CURRENT (< 3.
PAGE 2
L6565 DESCRIPTION (continued) Converter's power capability variations with the mains voltage are compensated by line voltage feedforward. At light load the device features a special function that automatically lowers the operating frequency still maintaining the operation as close to ZVS as possible. In addition to very low start-up and quiescent currents, this feature helps keep low the consumption from the mains at light load and be Blue Angel and Energy Star compliant.
PAGE 3
L6565 THERMAL DATA Symbol Rth j-amb Parameter Max. Thermal Resistance, Junction-to-ambient SO8 Minidip Unit 150 100 °C/W ABSOLUTE MAXIMUM RATINGS Symbol Pin IVcc 8 ICC + IZ IGD 7 Output Totem Pole Peak Current (2 µs) INV, COMP, VFF, CS Parameter Value Unit 30 mA ±700 mA -0.3 to 7 V 50 (source) -10 (sink) mA 1 0.
PAGE 4
L6565 ELECTRICAL CHARACTERISTCS (continued) (Tj = -25 to 125°C, VCC = 12V, Co = 1nF; unless otherwise specified) Symbol Parameter Min. Typ. Open loop 60 80 Source Current VCOMP = 4V, VINV = 2.4 V -2 -3.5 Sink Current VCOMP = 4V, VINV = 2.6 V 2.5 4.5 GV Voltage Gain GB Gain-Bandwidth Product ICOMP VCOMP Test Condition Max. dB 1 Upper Clamp Voltage ISOURCE = 0.5 mA Lower Clamp Voltage ISINK = 0.5 mA 5 2.25 VCS = 0 Unit MHz -5 mA mA 5.5 V 2.55 V -0.
PAGE 5
L6565 Figure 1. Supply current vs. Supply voltage ICC (mA) Figure 4. Line feedforward characteristics Vcsx [V] 1.5 Upper clamp 10 5.0 V 5 1 1 4.5 V 0.5 4.0 V 0.1 0.5 3.5 V 0.05 CL = 1nF f = 70KHz TA = 25°C 0.01 0.005 3.0 V 0 VCOMP = 2.5V 0 0 0 5 10 15 20 0.5 1 VCC(V) Figure 2. Start-up & UVLO vs. Temperature 1.5 2 2.5 3 3.5 VVFF [V] Figure 5.
PAGE 6
L6565 Figure 7. Gate-drive output saturation Figure 10. Zener voltage at Vcc pin vs. Tj Vpin7 [V] Vz [V] 2.5 22 Tj = 25 °C Vcc = 14.5 V SINK 2 21 1.5 20 1 19 0.5 0 0 100 200 300 400 500 18 -50 0 50 100 150 Tj [°C] IGD [mA] Figure 11. Start-up timer period vs. Tj Figure 8. Gate-drive output saturation TSTART [µs] Vpin7 [V] 0 Vcc - 0.5 450 Tj = 25 °C Vcc = 14.5 V SOURCE Vcc --0.5 0.5 Vcc=12V 400 Vcc - 1.0 -1 350 Vcc --1.5 1.5 300 Vcc - 2.0 -2 Vcc - 0.5 -2.
PAGE 7
L6565 APPLICATION INFORMATION Quasi-resonant operation in offline flyback converters lies in synchronizing MOSFET's turn-on to the transformer's demagnetization. Detecting the resulting negative-going edge of the voltage across any winding of the transformer can do this. The L6565 is provided with a dedicated pin that allows doing the job with a very simple interface, just one resistor.
PAGE 8
L6565 Zero Current Detection and Triggering Block (see fig. 13): The Zero Current Detection (ZCD) block switches on the external MOSFET if a negative-going edge falling below 1.6 V is applied to the input (pin 5, ZCD). However, to ensure high noise immunity, the triggering block must be armed first: prior to falling below 1.6V, the voltage on pin 5 must experience a positive-going edge exceeding 2.1 V.
PAGE 9
L6565 the L6565 puts a limit on the minimum OFF-time of the switch. This is done by blanking the triggering block of the ZCD circuit as mentioned before. The duration of the blanking time (3.5µs min.) is a function of the error amplifier output VCOMP, as shown in the diagram of figure 6. If the load current and the input voltage are such that the switch OFF-time falls below the minimum blanking time of 3.
PAGE 10
L6565 It acts on the clamp level of the control voltage Vcsx, that is on the overcurrent setpoint, so that it is a function of the converter's input voltage sensed through a dedicated pin (#3, VFF): the higher the input voltage, the lower the setpoint. This is illustrated in the diagram of figure 17a that shows the relationship between the voltage at the pin VFF and Vcsx (with the error amplifier saturated high in the attempt of keeping output voltage regulation).
PAGE 11
L6565 Error Amplifier Block (see fig. 17b): The Error Amplifier (E/A) inverting input is used in primary feedback technique to compare a partition of the voltage generated by the auxiliary winding with the internal reference, to achieve converter's output voltage regulation (see "Application Ideas", fig. 24).
PAGE 12
L6565 TYPICAL APPLICATIONS Figure 19. 50W Wide Range Mains SMPS for 14" TV C6 4700pF/ 4KV F1 2A fuse NTC1 16R D1 1N4148 C25 C24 1nF 100nF Vin C23 88 to 264 Vac 100nF R9 4.7M 3 B1 2KBP04M L1 15mH C1 150 µF 400 V C26 1nF R1 75k R2 75k R10 4.7M C22 100 pF T1 105 V 0.35 A C2 C8 8.
PAGE 13
L6565 APPLICATION IDEAS Here follows a series of ideas/suggestions aimed at either improving performance or solving common application issues of L6565-based power supplies. Figure 21. Enhanced turn-off for big MOSFET's drive Vcc 8 7 GD Q DRIVER BC327 L6565 Rs 6 GND Figure 22. Latched shutdown on: a) feedback disconnection; b) overload or short circuit Vcc Vcc 8 8 L6565 L6565 2 2 COMP COMP BC327 1N4148 BC327 1N4148 BC337 BC337 a) b) Figure 23.
PAGE 14
L6565 Figure 24. Primary Feedback loop configurations Vcc COMP Vcc COMP 8 2 RH 8 2 RH 1 1 - INV + - to VFF block E/A INV to VFF block E/A + RL RL 2.5V GND 2.5V GND L6565 6 a) L6565 6 b) Figure 25. Protection against secondary feedback disconnection by primary regulation take-over Figure 27. Remote ON/OFF control L6565 5 Vcc 15 V ZCD 8 INV 1 L6565 OFF 2 BC337 ON COMP 2.2 kΩ Figure 28. Low-consumption start-up circuit Figure 26.
PAGE 15
L6565 mm inch DIM. MIN. A TYP. MAX. MIN. 3.32 TYP. MAX. 0.131 a1 0.51 B 1.15 1.65 0.045 0.065 b 0.356 0.55 0.014 0.022 b1 0.204 0.304 0.008 0.012 0.020 D E 10.92 7.95 9.75 0.430 0.313 0.384 e 2.54 0.100 e3 7.62 0.300 e4 7.62 0.300 F 6.6 0.260 I 5.08 0.200 L Z 3.18 OUTLINE AND MECHANICAL DATA 3.81 1.52 0.125 0.150 Minidip 0.
PAGE 16
L6565 mm DIM. MIN. TYP. A a1 inch MAX. MIN. TYP. 1.75 0.1 0.25 a2 MAX. 0.069 0.004 0.010 1.65 0.065 a3 0.65 0.85 0.026 0.033 b 0.35 0.48 0.014 0.019 b1 0.19 0.25 0.007 0.010 C 0.25 0.5 0.010 0.020 c1 45° (typ.) D (1) 4.8 5.0 0.189 0.197 E 5.8 6.2 0.228 0.244 e 1.27 e3 0.050 3.81 0.150 F (1) 3.8 4.0 0.15 0.157 L 0.4 1.27 0.016 0.050 M S 0.6 0.024 8 ° (max.) (1) D and F do not include mold flash or protrusions.
PAGE 17
L6565 Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this publication are subject to change without notice.