■ DESCRIPTION

The MB3875 and MB3877 are charging DC/DC converter ICs suitable for down- conversion, which uses pulse width modulation (PWM) for controlling the output voltage and current independently. These ICs can dynamically control the secondary battery’s charge current by detecting a voltage drop in an AC adapter in order to keep its power constant (dynamically-controlled charging). The charging method enables quick charging, for example, with the AC adapter during operation of a notebook PC.

■ FEATURES

• Detecting a voltage drop in the AC adapter and dynamically controlling the charge current (Dynamically-controlled charging)
• High efficiency : 95 %
• Wide range of operating supply voltages: 7 V to 25 V
• Output voltage precision (Output voltage setting resistor integrated): 0 ± 0.8 % (Ta = + 25 °C)
• High precision reference voltage source: 4.2 V ± 0.8 %
• Support for frequency setting using an external resistor (Frequency setting capacitor integrated) :100 kHz to 500 kHz
• On-chip current detector amplifier with wide in-phase input voltage range : 0 V to VCC
• On-chip standby current function: 0 µA (Typ)
• On-chip soft-start function
• Internal totem-pole output stage supporting P-channel MOS FETs devices