RT8541GQW

RT8541/A 90V Boost DC/DC Converter with APD Current Monitor General Description Features zz z zz Integrated Schottky Diodes for Boost Converter and The RT8541/A is a constant frequency current mode PWM Charge Pump Voltage Doubler step-up DC/DC converter designed to bias avalanche zz z zz 50V, 400mA Internal Switch photodiodes (APD) at high voltage in optical receivers. It zz z zz High Side Low Noise and Accurate APD Current includes a voltage doubler charge pump to significantly Monitor reduce the noise level at output up to 90V. The RT8541A zz z zz 650kHz Fixed Switching Frequency for RT8541 and switching frequency can be adjusted by a resistor while Adjustable Switching Frequency for RT8541A RT8541 is internally set at 650kHz. The RT8541/A has a zz z zz Wide VIN Range : 2.7V to 16V built-in APD current mirror that delivers 1/5 of the APD zz z zz Adjustable APD Current Limit with External Resistor current with high accuracy for monitoring the APD current zz z zz Low Shutdown Current <1A from 0.2A to 2.5mA. This current can be used as a zz z zz Built-In Soft-Start reference to provide a digital programmed output voltage zz z zz CTRL Pin Allows Output Adjustment with no Polarity via the CTRL pin. To protect the optical receiver system, Inversion the RT8541/A provides a built-in adjustable APD current zz z zz Thin 16-Lead WQFN Package limit function by sensing a 200mV voltage threshold zz z zz RoHS Compliant and Halogen Free between VOUT2 and MONIN pins. Only one resistor is needed to program the desired current limit. A charge pump Applications voltage doubler is designed to achieve significantly lower noise level at the APD comparing to a simple boost z APD Bias converter type bias circuit. z PIN Diode Bias z Optical Receivers and Modules The RT8541/A also features a built-in 9ms soft-start z Fiber Optic Network Equipment function to eliminate the inrush current during start-up interval. The RT8541/A provides a low cost optical receiver solution and can fit in very small PCB area. The RT8541/A is available in the WQFN-16L 3x3 package. Simplified Application Circuit C1 L V IN C IN SW PUMP VIN RT8541/A R6 CTRL MONIN V OUT R5 C SHDN OUT VOUT2 C2 VC R2 VOUT1 C FSET FB R4 C3 R SET FB C4 MON R1 APD R3 GND Copyright 2013 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. DS8541/A-00 August 2013 www.richtek.com 1RT8541/A Ordering Information Pin Configurations RT8541/A (TOP VIEW) Package Type QW : WQFN-16L 3x3 (W-Type) Lead Plating System 16 15 14 13 G : Green (Halogen Free and Pb Free) 1 12 VC SHDN Adjustable Switching Frequency APD 2 11 VIN GND 3 10 MONIN GND Fixed Switching Frequency 17 4 9 VOUT2 GND Note : 5 6 7 8 Richtek products are : RoHS compliant and compatible with the current require- ments of IPC/JEDEC J-STD-020. WQFN-16L 3x3 Suitable for use in SnPb or Pb-free soldering processes. RT8541 Marking Information RT8541GQW 16 15 14 13 8C= : Product Code VC 1 12 SHDN 2 11 YMDNN : Date Code APD VIN 8C=YM GND MONIN 3 10 GND DNN 17 VOUT2 4 9 GND 5 6 7 8 RT8541AGQW 1G= : Product Code WQFN-16L 3x3 YMDNN : Date Code 1G=YM RT8541A DNN Copyright 2013 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. www.richtek.com DS8541/A-00 August 2013 2 VOUT1 MON VOUT1 MON PUMP FSET PUMP NC SW FB SW FB SW CTRL SW CTRL