Datasheet LT1738 (Analog Devices) - 20

LT1738
U TYPICAL APPLICATIO Ultralow Noise 30W Offline Power Supply DANGER: HIGH VOLTAGE
L1 X1 + 100µF 1M P6KE200A 400V T1 D1 +V 0.1µF OUT 1 11 A1 90VAC BR1 12V 250VAC TO 264VAC 2.5A “X2” A2 MUR160 1M + C3 K A 330µF 3 7 X3 25V 6 12 C4 100k C2 + + VBIAS 330µF 2W 10Ω D4 330µF 25V BA521 25V 5 8 + – VOUT 12V 17 19 10 510k 56µF 5pF IN755 A 35V VIN NC NFB 470pF 600V 14 SHDN 5 V5 5pF 510k 6 2 SYNC CAP 1.8nF 7 1 CT GATE U3 MTP2N60E 0.1µF 165k 165k 1k 8 LT1738 4 VOUT RT CS 19.6k 16 18 0.068Ω 1k 2N2222 ISO1 RVSL NC 1/2W 0.22µF 3.9k CNY17-3 15 20 3 1 3 2 38.3k RCSL PGND 6 1% 3.9k V+ COMP 8 1k 9 12 5 U2 REF FB VC LT1431 2 4 COLL SS GND GCL RTOP 2N2222 7 10k 13 11 3 RMIO 1% 51k 4 10nF G-F G-S VBIAS 6 5 1738 TA02 UNLESS OTHERWISE NOTED: ALL RESISTORS 1206, 5% D1: MBR20200CT NOTE: PIN 2 OF LT1738 MUST BE LAID OUT BR1: GENERAL INSTRUMENTS W06G L1: HM18-10001 AWAY FROM FAST SLEWING NODES C2, C3, C4: SANYO MV-GX T1: PREMIER MAGNETICS POL-15033 INPUT FILTER IS REQUIRED TO ATTENUATE SWITCHING FREQUENCY HARMONICS AND PASS FCC CLASS B (LT1738 DOES NOT ATTENUATE THESE LOW FREQUENCY HARMONICS) MAIN ADVANTAGE WITH LT1738 IS IT MAKES SUPPRESSING THE HIGH FREQUENCY NOISE AND EMI EASY. THIS IS PARTICULARLY USEFUL FOR MEDICAL DEVICES BECAUSE THE AC LINE TO EARTH GND CAPS ON THE INPUT FILTER CAN BE ELIMINATED; ALLOWING THE DEVICE TO PASS THE EARTH GND LEAKAGE CURRENT MEDICAL SPECIFICATIONS.
RELATED PARTS PART NUMBER DESCRIPTION COMMENTS
LT1683 Ultralow Noise Push-Pull DC/DC Controller Dual Output (Push-Pull) Current Mode Architecture. LT1425 Isolated Flyback Switching Regulator Excellent Regulation without Transformer “Third Winding” LT1533 Ultralow Noise 1A Switching Regulator Push-Pull Design for Low Noise Isolated Supplies LT1534 Ultralow Noise 2A Switching Regulator Ultralow Noise Regulator for Boost Topologies LT1576 1.5A, 200kHz Step-Down Switching Regulator Constant Frequency, 1.21V Reference Voltage LT176X Family Low Dropout, Low Noise Linear Regulator 150mA to 3A, SOT-23 to TO-220 LT1777 Low Noise Step-Down Switching Regulator Programmable dI/dt; Internally Limited dV/dt LTC1922-1 Synchronous Phase Modulated Full-Bridge Controller Adaptive DirectSenseTM Zero Voltage Switching, 50W to Kilowatts, Synchronous Rectification LT3439 Ultralow Noise Transformer Driver 1A Push-Pull DC/DC Transformer Driver DirectSense is a trademark of Linear Technology Corporation. 1738fa LT/TP 1202 1K REV A • PRINTED IN USA 20 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com LINEAR TECHNOLOGY CORPORATION 2001