SG6846A Fairchild Semiconductor, SG6846A Datasheet
SG6846A
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SG6846A Summary of contents
Page 1
... Besides the cycle-by-cycle current limiting, if the switching current is higher than two thirds the peak- current threshold for 1700ms, over-current protection is activated such that the SG6846A is latched off. If the switching current is higher than two thirds of the peak-current threshold for 100ms, and the voltage on ...
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... Typical Application L EMI AC input Filter N VIN SG6846A Block Diagram © 2008 Fairchild Semiconductor Corporation SG6846A • Rev. 1.1 VDD GATE 8 SENSE 6 GND Figure 1. Typical Application Figure 2. Block Diagram 2 VO+ + VO- www.fairchildsemi.com ...
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... Marking Information SG6846AFTP XXXXXXXXYWWV ※ Marking for SG6846ALSZ (Pb-Free) ※ Marking for SG6846ALSY (Green-compound), SG6846ACSY (Green-compound) © 2008 Fairchild Semiconductor Corporation SG6846A • Rev. 1.1 OCP Latch SOP Lead Free + ROHS Compatible Null = regular package XXXXXXXX: Wafer Lot Y: Year; WW: Week V: Assembly Location Figure 3 ...
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... The sensed voltage is used for peak-current-mode control and cycle-by-cycle current limiting. If the switching current is higher than OCP threshold and lasts for 1700ms, SG6846A turns off immediately. This two-level OCP feature is especially suitable for SMPS with surge current output open-circuit failure occurs in the feedback loop, the internal protection circuit disables PWM output as long as V The totem-pole output driver for the power MOSFET ...
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... The Recommended Operating Conditions table defines the conditions for actual device operation. Recommended operating conditions are specified to ensure optimal performance to the datasheet specifications. Fairchild does not recommend exceeding them or designing to Absolute Maximum Ratings. Symbol T Operating Ambient Temperature A © 2008 Fairchild Semiconductor Corporation SG6846A • Rev. 1.1.5 Parameter <50°C SOP A SOP Parameter 5 Min ...
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... OCP Threshold Voltage for Current Limit STH3V-2/3 t Delay Time for Over-Current Protection D-OCP Delay Time for Output Short-Circuited t D-SCP Protection t SS-65KHz Period During Startup Time t SS-130KHz © 2008 Fairchild Semiconductor Corporation SG6846A • Rev. 1.1.5 Test Condition Min. 15.5 9 DD-OFF +0. – 0.16V DD-ON GATE Open 22 26kΩ ...
Page 7
... Frequency Variation vs Frequency Variation vs. Temperature f DT Deviation © 2008 Fairchild Semiconductor Corporation SG6846A • Rev. 1.1 Timing = 1700ms OCP (7) Gate Off Figure 6. SG6846A OCP/SCP Logic Flow Diagram (Continued) Test Condition Center Frequency R = 26kΩ Jitter Range Center Frequency R = 13kΩ, V ...
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... NOR I RI Maximum R Value for Protection MAX I RI Minimum R Value for Protection MIN I Note: 1. The relationship between R © 2008 Fairchild Semiconductor Corporation SG6846A • Rev. 1.1.5 Figure 7. PWM Frequency (Continued) Test Condition V = 15V 12V GATE = 1nF GATE = 1nF V = 20V DD ( 26kΩ ...
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... Temperature (℃) Figure 10. Startup Current (I 2.5 2.0 1.5 1.0 0.5 0.0 -40 - 109 125 Temperature (℃) Figure 12. PWM Turn-off Threshold Voltage (V vs. Temperature © 2008 Fairchild Semiconductor Corporation SG6846A • Rev. 1.1.5 11.5 11.1 10.7 10 110 125 ) Figure 9. Turn-off Threshold Voltage (V DD- vs. Temperature Figure 11. Startup Current vs. V DD-ST 1 ...
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... Figure 16. Current-Limit Threshold vs. V 71.0 70.5 70.0 69.5 69.0 68.5 -40 -25 - 110 125 Temperature (℃) Figure 18. Output Current of RT Pin (I vs. Temperature © 2008 Fairchild Semiconductor Corporation SG6846A • Rev. 1.1.5 (Continued 110 125 ) Figure 15. PWM Frequency vs. FB Voltage OSC 0 ...
Page 11
... Over-Temperature Protection (OTP) An external NTC thermistor can be connected from the RT pin to GND. The impedance of the NTC decreases at high temperatures. When the voltage of the RT pin drops below 1.05V, the SG6846A is turned off. For Increasing the protection-mode options, see Ordering Information. and the ...
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... Slope compensation helps alleviate this problem. Good placement and layout practices should be followed. Avoid long PCB traces and component leads. Compensation and filter components should be located near the SG6846A. © 2008 Fairchild Semiconductor Corporation SG6846A • Rev. 1.1.5 (Continued) 12 Figure 20 ...
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... R14 0Ω22 ±5% R16, R17 1W 20Ω ±5% R11 20KΩ ±5% R12 100KΩ ±5% R20 887KΩ ±1% R22 10KΩ ±1% © 2008 Fairchild Semiconductor Corporation SG6846A • Rev. 1.1.5 BD1 LF2 CX2 R12 ...
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... Package specifications do not expand the terms of Fairchild’s worldwide terms and conditions, specifically the warranty therein, which covers Fairchild products. Always visit Fairchild Semiconductor’s online packaging area for the most recent package drawings: http://www.fairchildsemi.com/packaging/ © 2008 Fairchild Semiconductor Corporation SG6846A • Rev. 1.1.5 5.00 4.80 A 3.81 ...
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... Fairchild Semiconductor Corporation SG6846A • Rev. 1.1.5 15 www.fairchildsemi.com ...