FUJITSU SEMICONDUCTOR
DATA SHEET
DS04-27706-1E
ASSP
For Power Supply Applications (Secondary battery)
DC/DC Converter IC for Charging
MB3878
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DESCRIPTION
The MB3878 is a DC/DC converter IC suitable for down-conversion, using pulse-width (PWM) charging and
enabling output voltage to be set to any desired level from one cell to four cells.
These ICs can dynamically control the secondary battery’s charge current by detecting a voltage drop in an AC
adaptor in order to keep its power constant (dynamically-controlled charging).
The charging method enables quick charging, for example, with the AC adaptor during operation of a notebook PC.
The MB3878 provides a broad power supply voltage range and low standby current as well as high efficiency,
making it ideal for use as a built-in charging device in products such as notebook PC.
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FEATURES
• Detecting a voltage drop in the AC adaptor and dynamically controlling the charge current
(Dynamically-controlled charging)
• Output voltage setting using external resistor
: 1 cell to 4 cells
• High efficiency
: 94
%
• Wide range of operating supply voltages
: 7 V to 25 V
• Output voltage setting accuracy
: 4.2V
±
0.8% (per cell)
• Built-in frequency setting capacitor enables frequency setting using external resistor only
• Oscillator frequency range
: 100kHz to 500kHz
• Built-in current detector amplifier with wide in-phase input voltage range : 0 V to Vcc
• In standby mode, leave output voltage setting resistor open to prevent inefficient current loss
• Built-in standby current function
: 0
µA
(standard)
• Built-in soft start function
• Built-in totem-pole output stage supporting P-channel MOS FETs devices
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PACKAGE
24-pin plastic SSOP
(FPT-24P-M03)
FUJITSU [ FUJITSU COMPONENT LIMITED. ]
