mb3843pfv Fujitsu Microelectronics, Inc., mb3843pfv Datasheet - Page 17

• Manufacturer Part Number: mb3843pfv
• Description: Lithium Ion Battery Charger Dc/dc Converter Ic High Precision With Constant-current Function
• Manufacturer: Fujitsu Microelectronics, Inc.

METHOD OF SETTING THE CHARGING CURRENT
The charging current level (output limit current level) is set at the Vin2 terminal (pin 8) .
METHOD OF SETTING THE SOFT-START TIME
• At start up, the capacitor (Cs) connected to the CS terminal (pin 11) begins charging. The error amplifier
• Because the CS terminal voltage is input to the error amplifier, the soft-start time setting is not dependent on
OSCILLATOR FREQUENCY SETTING
The oscillator frequency can be set by connecting a timing capacitor (C
resistor (R
ERROR AMP. BLOCK OVERSHOOT PROTECTION CIRCUIT
This built-in circuit responds to rapid fluctuations in charging current such as can occur when inserting or removing
a chargeable battery, by clamping an inverted input signal ( IN1 or IN2) from the error amps (Error Amp.1 or
Error Amp.2) to suppress changes in output voltage.
Charging current level (output limit current level)
compares the soft-start setting voltage, which is proportional to the CS terminal voltage, to the output feedback
voltage and produces a soft-start by varying the ON duty at the OUT terminal (pin 15) . The soft-start time can
be determined by the formula below.
the output current value.
Oscillator frequency : f
Soft-start time (time to output setting voltage VD)
T
) to the RT terminal (pin 12) .
f
OSC
IL (Max.) [A]
ts [s] 2.5
(kHz) : =
OSC
Cs [ F]
C
T
25
(pF) R
Vin2 (V)
990000
RS ( )
T
(k )
MB3813A/MB3833A/MB3843
RS output sensing resistance
T
) to the CT terminal (pin 13) and a timing
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