MIC9131 Micrel, Inc. MIC9131 High-Voltage, High-Speed Telecom DC-to-DC Controller General Description Features The MIC9131 is a current-mode PWM controller that efciently Input voltages up to 180V converts 48V telecom voltages to logic levels. The MIC9131 Internal oscillator capable of > 2.5MHz operation features a high voltage start-up circuit that allows the device to Accurate 75% maximum duty cycle be connected to input voltages as high as 180V. The high input Synchronisation capability to 6MHz voltage capability protects the MIC9131 from line transients Current sense delay of 34ns that are common in telecom systems. The start-up circuitry Minimum pulse width of <25ns also saves valuable board space and simplies designs by 90% efciency integrating several external components. 1.3mA quiescent current 1A shutdown current The MIC9131 is capable of high speed operation. Typically Soft-start the MIC9131 can control a sub-25ns pulse width on the gate Resistor programmable current sense threshold out pin. Its internal oscillator can operate over 2.5MHz, with Selectable soft-start retry even higher frequencies available through synchronisation. 4 sink, 12 source output driver The high speed operation of the MIC9131 is made safe by Programmable under-voltage lockout the very fast, 34ns response from current sense to output, Constant-frequency PWM current-mode control minimizing power dissipation in a fault condition. 16-pin SOIC and 16-pin QSOP The MIC9131 allows for the designs of high efciency power supplies. It can achieve efciencies over 90% at high output Applications currents. Its low 1.3mA quiescent current allows high efciency Telecom power supplies even at light loads. Line cards The MIC9131 has a maximum duty cycle of 75%. For designs ISDN network terminators requiring a maximum duty cycle of 50%, refer to the MIC9130. Micro- and pico-cell base stations The MIC9131 is available in a 16-pin SOP and 16-pin QSOP Low power (< 100W) dc-dc converters package options. The junction temperature range is from DSL line cards 40C to +125C. Typical Application 10 1N5818 12V 10F 25V 4:1 VIN VOUT 36V to 72V 3.3V 20A 6:1 0.1F Si4884DY 1.5H L = 530H 1M (x2) 100F B320A 37.4k 13 1 2 10 Si4884DY (x2) 7 FB 16 10k OUT IRFS3IN20D 6 COMP SLOPE MIC9131 COMPENSATION 3 RBIAS 12 SS ISNS 14 8.2k 8 CPWR 562k 9 VBIAS 0.1 0.1F 1W OSC SYNCAGND PGND 4 5 11 15 2.61k 10nF 270pF OPTO FEEDBACK 90% Efcient Telecommunications Power Supply Micrel, Inc. 2180 Fortune Drive San Jose, CA 95131 USA tel + 1 (408) 944-0800 fax + 1 (408) 474-1000 MIC9131 Micrel, Inc. Ordering Information Part Number Max. Duty Cycle Junction Temp. Range Package Standard Pb-Free MIC9131BM MIC9131YM 75% -40C to +125C 16-Pin SOP MIC9131BQS MIC9131YQS 75% -40C to +125C 16-Pin QSOP Pin Conguration LINE 1 16 OUT 15 VCC 2 PGND 3 14 RBIAS ISNS 13 OSC 4 UVLO 5 12 SYNC SS 11 COMP 6 AGND FB 7 10 EN 9 CPWR 8 VBIAS 16-Pin SOP (M) 16-Pin QSOP (QS) Pin Description Pin Number Pin Name Pin Function 1 LINE Line (Input): 180Vdc maximum supply input. May be oated if unused. 2 VCC Supply (Input): MIC9131 internal supply input. 3 RBIAS Bias Resistor (External Component): Connect 562K to ground. 4 OSC Oscillator RC Network (External Components): Connect external resistor-ca- pacitor network to set oscillator frequency. 5 SYNC Synchronization (Input): External oscillator input for slave operation of con- troller. See OSC. Do not oat. 6 COMP Compensation (External Components): Error amplier output for external compensation network connection. 7 FB Feedback (Input): Error amplier inverting input. 8 CPWR Current Limit Selection (Input): When CPWR is high, an over-current condi- tion at the ISNS input will terminate the gate drive and reset the soft-start latch. If the CPWR pin is low, an over-current condition at the ISNS input will terminate the gate drive signal, but will not cause a reset of the soft-start circuit. 9 VBIAS Reference (Output): Internal 5V supply. Will source 5mA maximum. 10 EN Enable (Input): Logic level enable/shutdown input logic high = enabled (on), logic low = shutdown (off). 11 AGND Analog Ground (Return) 12 SS Soft-Start (External Components): Connect external capacitor to slowly ramp up duty cycle during startup and over-current conditions. 13 UVLO Undervoltage Lockout (External Components): Connect to unbiased resistive divider network to set controllers minimum operating voltage. Connect to VBIAS if not needed. 14 ISNS Current Sense (Input): Connect between external switching MOSFET source and switch current sense resistor. 15 PGND Power Ground (Return) 16 OUT Switch Drive Output (Output): Connect to gate of external switching MOS- FET. M9999-080206 2 August 2006