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MB3871 Dataheets PDF



Part Number MB3871
Manufacturers Fujitsu Media Devices
Logo Fujitsu Media Devices
Description Mobile Pentium II DC/DC Converter
Datasheet MB3871 DatasheetMB3871 Datasheet (PDF)

FUJITSU SEMICONDUCTOR DATA SHEET DS04-27219-3E ASSP For Power Supply Applications Mobile Pentium® II DC/DC Converter IC MB3871 s DESCRIPTION The FUJITSU MB3871 is a pulse width modulation (PWM) DC/DC converter IC chip that provides a selection of 1.3 V to 2.0 V output voltages for Mobile Pentium® II* CPU’s, using a 4-bit input signal information. The MB3871 utilizes synchronous rectification for high efficiency and features a soft-start/discharge control function for ease in designing power .

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FUJITSU SEMICONDUCTOR DATA SHEET DS04-27219-3E ASSP For Power Supply Applications Mobile Pentium® II DC/DC Converter IC MB3871 s DESCRIPTION The FUJITSU MB3871 is a pulse width modulation (PWM) DC/DC converter IC chip that provides a selection of 1.3 V to 2.0 V output voltages for Mobile Pentium® II* CPU’s, using a 4-bit input signal information. The MB3871 utilizes synchronous rectification for high efficiency and features a soft-start/discharge control function for ease in designing power supplies in multi-supply systems, making it ideal for Mobile Pentium® II power supply systems. * : Pentium is the registered trademark of Intel Corporation. s FEATURES • • • • • • • • Highly efficient for using synchronous rectification scheme On-chip soft-start/discharge control circuit High precision output voltage: ±1.2% 4-bit, 16-step DAC: 2.0 V to 1.3 V in 50 mV steps Frequency range: 100 kHz to 500 kHz using variable resistance (on-chip frequency setting capacitance) Standby current: 0 µA TYP On-chip PWRGOOD circuit for output voltage state detection Timer-latch short-circuit protection circuit, and overvoltage protection circuit for output protection s PACKAGE 24-pin Plastic SSOP (FPT-24P-M03) MB3871 s PIN ASSIGNMENT (Top view) RT : 1 RS : 2 SGND : 3 CS : 4 –IN : 5 FB : 6 ENB : 7 OUT1 : 8 VS : 9 CB : 10 OUT2 : 11 PGND : 12 24 : VREF 23 : VCC 22 : CSCP 21 : PWRGOOD 20 : VSENSE 19 : CTL 18 : TEST 17 : VD3 16 : VD2 15 : VD1 14 : VD0 13 : VB (FPT-24P-M03) 2 MB3871 s PIN DESCRIPTION Pin no. 1 2 3 4 5 6 7 8 9 10 Symbol RT RS SGND CS –IN FB ENB OUT1 VS CB I/O — — — — I O I O — — Descriptions Triangular wave frequency setting resistor connection pin Discharging resistor connection pin for soft start capacitor Ground pin Soft start capacitor connection pin (Also used for discharge control) Error amplifier inverted input pin Error amplifier output pin Discharge control function enable/disable switch control pin Totem-pole output pin (External main-side FET gate drive) External main-side FET source-side connection Output bootstrap pin Insert a capacitor between the CB and VS pins, to bootstrap the IC internal output transistor. Totem-pole output pin (External synchronous rectifier-side FET gate drive) Ground pin Output circuit power supply pin 4-bit digital input pin used to set DC/DC converter output voltage 4-bit digital input pin used to set DC/DC converter output voltage 4-bit digital input pin used to set DC/DC converter output voltage 4-bit digital input pin used to set DC/DC converter output voltage Test pin for D/A output. Set to open when in use. Power supply control pin The CTL pin is set to “L” level to place the IC in standby mode. PWRGOOD circuit input pin PWRGOOD output pin (open-drain output) Outputs a “H” level signal when the output voltage is within the range from VTLOW to VTHIGH. Timer-latch short-circuit protection capacitor connection pin Power supply pin for reference power and control circuit Reference voltage output pin 11 12 13 14 15 16 17 18 19 20 21 OUT2 PGND VB VD0 VD1 VD2 VD3 TEST CTL VSENSE PWRGOOD O — — I I I I — I I O 22 23 24 CSCP VCC VREF — — O 3 MB3871 s BLOCK DIAGRAM VSENSE 20 CS POWERGOOD PWRGD PWRGOOD 21 (±10%) 13 VB –IN 5 – + + Error Amp. Overvoltage protection (17.5%) OVP PWM Comp.1 + + DTC – PWM Comp.2 + – 10 Drive 1 8 9 CB OUT1 VS FB RS 6 VB 2 CS 4 Drive 2 OUT2 11 12 PGND + VD0 14 VD1 15 VD2 16 VD3 17 + OSC TEST 18 CT (40 pF) 1 RT VSCP – SCP UVLO Ref D/A (4-bit) SCP Comp. bias Power ON/OFF CTL VCC 23 VCS – CS Comp. bias CTL LOGIC 19 CTL 7 ENB (3.5 V) 22 CSCP 24 3 VREF SGND 4 MB3871 s OUTPUT VOLTAGE SETTING CODE VD3 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 VD2 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 VD1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 VD0 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 Output voltage setting (V) 2.000 1.950 1.900 1.850 1.800 1.750 1.700 1.650 1.600 1.550 1.500 1.450 1.400 1.350 1.300 0 (output OFF) 5 MB3871 s ABSOLUTE MAXIMUM RATINGS Parameter Power supply voltage Bias voltage Boot voltage Control input voltage PWRGOOD output voltage Output current Peak output current Allowable dissipation Storage temperature Symbol VCC VB VCB VCTL VPWRGD IO IO PD Tstg Ta ≤ +25°C — Condition — — — — — — Duty ≤ 5% (t = 1/fOSC × Duty) Value 20 20 32 20 17 120 800 740* –55 to +125 Unit V V V V V mA mA mW °C * : When mounted on a 10 cm-square dual-sided epoxy base board WARNING: Semiconductor devices can be permanently damaged by application of stress (voltage, current, temperature, etc.) in excess of absolute maximum ratings. Do not exceed these ratings. 6 MB3871 s RECOMMENDED OPERATING CONDITIONS Parameter Power supply voltage Bias voltage Boot voltage Reference voltage output current Symbol VCC VB VCB IOR VIN Input voltage VIN VIN Output current Peak output current Oscillator frequency Timing resistance Boot capacitance Reference voltage output capacitance Soft start capacitance Discharge control resistance Short detection capacitance Operating temperature IO IPG IO fOSC R.


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