SG6905

Manufacturer Part NumberSG6905
ManufacturerFairchild Semiconductor
SG6905 datasheet
 


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Green mode PFC/Flyback-PWM Controller
FEATURES
Interleaved PFC/PWM switching
Green mode PWM operation
Low start-up and operating current
Innovative switching charge multiplier-divider
Multi-vector control for improved PFC output
transient response
Average-current-mode control for PFC
PFC over-voltage and under-voltage protections
PFC remote on/off Control
PFC and PWM feedback open-loop protection
Cycle-by-cycle current limiting for PFC/PWM
Slope compensation for PWM
Constant power limit for PWM
Power-on sequence control
Brownout protection
Over temperature protection
APPLICATIONS
Switching Power Suppliers with Active PFC
High-Power Adaptors
DESCRIPTION
The highly integrated SG6905 is specially designed for
power supplies with boost PFC and flyback PWM. It
requires
very
few
external
TYPICAL APPLICATION
© System General Corp.
Version 1.1.1 (IAO33.0060.B1)
achieve versatile protections. It is available in a 20-pin
SOP package.
The patented interleave-switching feature synchronizes
the PFC and PWM stages and reduces switching noise.
For PFC stage, the proprietary multi-vector control
scheme provides a fast transient response in a
low-bandwidth PFC loop, in which the overshoot and
undershoot of the PFC voltage are clamped. If the
feedback loop is broken, the SG6905 will shut off PFC to
prevent extra-high voltage on output.
For the flyback PWM, the synchronized slope
compensation ensures the stability of the current loop
under continuous-conduction-mode operation. Built-in
line-voltage
output-power limit. Hiccup operation during output
overloading is also guaranteed.
During start-up, the RDY pin will be pulled low until the
PFC output voltage reaches to the setting level. This
signal can be used to control the second power stage for
proper power on sequence.
SG6905 provides complete protection functions such as
brownout protection and RI pin open/short.
components
to
- 1 -
www.sg.com.t w • www.fairchildsemi.com
Product Specification
SG6905
compensation
maintains
constant
September 27, 2007

SG6905 Summary of contents

  • Page 1

    ... PFC loop, in which the overshoot and undershoot of the PFC voltage are clamped. If the feedback loop is broken, the SG6905 will shut off PFC to prevent extra-high voltage on output. For the flyback PWM, the synchronized slope compensation ensures the stability of the current loop under continuous-conduction-mode operation ...

  • Page 2

    ... SOP P : SG6905TP XXXXXXXX: Wafer Lot XXXXXXXXYWWV Y: Year; WW: Week V: Assembly Location ORDERING INFORMATION Part Number Pb-Free SG6905SZ © System General Corp. Version 1.1.1 (IAO33.0060.B1) PIN CONFIGURATION Z =Lead Free Null=regular package Package 20-pin SOP - 2 - www.sg.com.t w • www.fairchildsemi.com Product Specification SG6905 September 27, 2007 ...

  • Page 3

    ... An external NTC thermistor must be connected from this pin to ground. The impedance of the NTC thermistor decreases whenever the temperature increases. Once the voltage of the OTP pin drops below the OTP threshold, the SG6905 will be disabled. This is the output of the PFC current amplifier. The signal from this pin will be compared with an internal saw-tooth and hence determine the pulse width for PFC gate drive ...

  • Page 4

    ... Green mode PFC/Flyback-PWM Controller BLOCK DIAGRAM © System General Corp. Version 1.1.1 (IAO33.0060.B1) Product Specification - 4 - www.sg.com.t w • www.fairchildsemi.com SG6905 September 27, 2007 ...

  • Page 5

    ... UNLESS NOTED Test Conditions Min. V -0.16V DD- 15V; RI= 24KΩ DD OPFC, OPWM open 15 9 23.5 RI= 24KΩ DD-OFF +0 www.sg.com.t w • www.fairchildsemi.com Product Specification SG6905 Unit °C °C °C/W ° Unit °C Typ. Max. Unit µA ...

  • Page 6

    ... RI= 24KΩ Test Conditions Min. Typ 1 0~1. 3.2 RI= 24 KΩ (I =20+I *0. 0. www.sg.com.t w • www.fairchildsemi.com Product Specification SG6905 Max. Unit 0. RMS-UVP- RMS-UVP- V +0.19 +0. UVP-Min ms +14 240 ms Max. Unit 3. KΩ 3.3 V 120 mV 120 µs 3.2 V µA/mV 2 ...

  • Page 7

    ... 13V 100mA 15V 5nF O/ 15V;C = 5nF O/ Test Conditions RI= 24KΩ RI= 24KΩ www.sg.com.t w • www.fairchildsemi.com Product Specification SG6905 Min. Typ. Max. Unit 90 100 110 µA 0.15 0.2 0.25 V 0.35 0.4 0.45 V 200 ns 70 120 170 ns Min. Typ. Max. ...

  • Page 8

    ... A Test Conditions V = 20V 15V 100mA 13V 100mA 15V 5nF O/ 15V 5nF O/ www.sg.com.t w • www.fairchildsemi.com Product Specification SG6905 Min. Typ. Max. Unit 2.5 3.1 3.5 V KΩ 0.8 1.2 1.5 mA 4.2 4.5 4 450 600 750 ms 1.8 2.0 2 ...

  • Page 9

    ... SINK 4 Test Conditions Min. Typ. RI= 24KΩ 90 100 1.35 1.4 1.15 1.2 RI= 24KΩ 8 Test Conditions Min. Typ. RT= 24KΩ 470 - 9 - www.sg.com.t w • www.fairchildsemi.com Product Specification SG6905 Max. Unit 2. µA 0 Max. Unit 110 µA 1. µs Max. Unit 56 µA Ω ...

  • Page 10

    ... Temperature D D 25.5 25.0 24.5 24.0 23 110 125 -40 - www.sg.com.t w • www.fairchildsemi.com Product Specification SG6905 ) Temperature - 110 Temperature ( ) ) ture OSC 110 125 ture ( ) Ove r Volta ge Prote ction (V ...

  • Page 11

    ... Ma xim um D uty C ycle ( 110 125 -40 -25 - www.sg.com.t w • www.fairchildsemi.com Product Specification SG6905 ) vs Temperature 110 125 Temperature ( ) ) vs Temperature 110 125 ...

  • Page 12

    ... Falling Time (t LIM IT 110 110 125 -40 -25 - www.sg.com.t w • www.fairchildsemi.com Product Specification SG6905 ) vs O FF-P WM-DLY Temperature 110 125 Temperature ( ) ) vs Temperature 110 125 Temperature ( ) ...

  • Page 13

    ... ture ( © System General Corp. Version 1.1.1 (IAO33.0060.B1) OTP Threshold V oltage ( AXPW M 1.25 1.23 1.21 1.19 1.17 1.15 -40 -25 - 110 125 ) - 13 - www.sg.com.t w • www.fairchildsemi.com Product Specification SG6905 ) Temperature 110 125 ture ( ) September 27, 2007 ...

  • Page 14

    ... PFC output voltage reaches to the setting level. This signal can be used to control the second power stage for proper power on sequence. SG6905 provides complete protection functions such as brownout protection and RI pin open/short. Start Up Figure 1 shows the start up circuit of the SG6905. A resistor R is utilized to charge V capacitor through S1 The turn-on and turn-off threshold of SG6905 are fixed internally at 16V/10V ...

  • Page 15

    ... Figure 2 shows a resistive divider with low-pass filtering for line-voltage detection on VRMS pin. The V voltage is used for the PFC multiplier and brownout protection. For brownout protection, the SG6905 is disabled with 195ms delay time if the voltage V drops below 0.8V. RMS For PFC multiplier, please refer to below section for more details ...

  • Page 16

    ... FIG.4 Average current mode control loop © System General Corp. Version 1.1.1 (IAO33.0060.B1) Product Specification From Equation the output of the voltage error EA amplifier, actually controls the total input power and hence the power delivered to the load www.sg.com.t w • www.fairchildsemi.com SG6905 September 27, 2007 ...

  • Page 17

    ... Either R is opened, OPFC of SG6905 will shut off immediately to prevent extra-high voltage on the output capacitor. FIG. 5 Multi-vector error amplifier Cycle-by-Cycle Current Limiting SG6905 provides cycle-by-cycle current limiting for both PFC and PWM stages ...

  • Page 18

    ... OPWM will then be turned off. As OPWM is turned off, the supply voltage VDD will also begin decreasing. When V is lower than the turn-off threshold (10V), SG6905 will be totally shut down. Due to the start up resistor, V will be charged up to the turn-on DD threshold voltage, V ...

  • Page 19

    ... Product Specification SG6905 Detail Detail A Max. 0.104 0.012 0.092 0.016 0.008 0.508 0.299 0.050 0.419 0.050 0.020X45 ˚ 0.004 8˚ ...

  • Page 20

    ... BASIC 0.635 1.270 0.016 1.041 BASIC 8˚ 0˚ www.sg.com.t w • www.fairchildsemi.com Product Specification SG6905 DETAIL : A Max. 0.064 0.069 0.006 0.010 0.059 0.012 0.010 0.341 0.344 0.236 0.244 0.154 0.157 0.025 BASIC 0.025 ...

  • Page 21

    ... Green mode PFC/Flyback-PWM Controller © System General Corp. Version 1.1.1 (IAO33.0060.B1) Product Specification - 21 - www.sg.com.t w • www.fairchildsemi.com SG6905 September 27, 2007 ...