MB3870

Features:

• Highly efficient for using synchronous rectification scheme
• On-chip soft-start/discharge control circuit
• High precision output voltage: ±1.2%
• 5-bit, 32-step DAC: 3.5 V to 2.1 V in 100 mV steps
                                  2.05 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 A TYP
• On-chip PWRGOOD circuit for output voltage state detection
• Timer-latch short-circuit protection circuit, and overvoltage protection circuit for output protection


Pinout




Specifications

Parameter	Symbol	Condition	Value	Unit
Power supply voltage	VCC	-	20	V
Bias voltage	VB	-	20	V
Boot voltage	VCB	-	32	V
Control input voltage	VCTL	-	20	V
PWRGOOD output voltage	VPWRGD	-	17	V
Output current	IO	-	20	mA
Peak output current	IO	Duty5% (t = 1/fOSC*Duty)	800	mA
Allowable dissipation	PD	Ta+25°C	740*	mW
Storage temperature	Tstg	-	55 to +125	°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.


Description

The FUJITSU MB3870 is a pulse width modulation (PWM) DC/DC converter IC chip that provides a selection of 1.3 V to 3.5 V output voltages for Pentium^®* CPU's, using a 5-bit input signal information.

The MB3870 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 Pentium^® II power supply systems.

* : Pentium is the registered trademark of Intel Corporation.