387685-05

■ DESCRIPTION

The MB3874 and MB3876 are parallel 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.
The IC also enable parallel charging, or charging two batteries at the same time, dramatically reducing the charging time.
With an on-chip output voltage setting resistor which allows the output voltage to be set at high precision, these ICs are best suited as internal battery chargers for notebook PCs.
The MB3874 support 3-cell battery and the MB3876 support 4-cell battery.

■ FEATURES

• Detecting a voltage drop in the AC adapter and dynamically controlling the charge current (Dynamically-controlled charging)
• High efficiency : 93 %(In reverse-current preventive diode)
• Wide range of operating supply voltages : 7 V to 25 V
• Output voltage precision (Built-in output voltage setting resistor ) : ± 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
• Built-in current detector amplifier with wide in-phase input voltage range : 0 V to VCC
• Built-in standby current function : 0 µA (Typ.)
• Built-in soft start function
• Capable of parallel charging (Charging the two battery packs at a time)
• Internal totem-pole output stage supporting P-channel MOS FETs devices