MB39A103 Datasheet, PDF (4/4 Pages) List of Unclassifed Manufacturers – 4-Channel DC/DC Converter IC with Support for Low Voltage

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MB39A103
PWM Comparator Block (PWM Comp.)
This is a voltage-pulse width modulator that controls the
output duty depending on input / output voltage. The output
transistor is turned ON while error amplifier output voltage
and DTC voltage are higher than triangular wave voltage.
Output Block (Drive)
The output circuit is constructed in totem pole style and is
capable of driving external Pch MOS FET (channel 1) and
Nch MOS FET (channel 2 to channel 4).
Channel Control Function
ON / OFF of each channel is specified by voltage specification
at CTL terminal and each CS terminal.
Table 1 shows the ON / OFF setting conditions.
Protection Circuit Function
Timer Latch Short-Circuit Protection Circuit Block
(SCP, SCP Comp.)
The short-circuit detection comparator detects the level of
error amplifier output voltage. When the error amplifier
output voltage on any channel exceeds the short-circuit
detection voltage, the timer circuit operates and starts charging
the capacitator CSCP externally connected to CSCP terminal.
When capacitator voltage reaches approximately 0.70V, output
transistor is turned OFF and the dead time is set to 100%.
Furthermore, short-circuit detection from an external
short-circuit detection comparator is possible using the -INS
terminal. When the protection circuit operates, latch is released
if power is turned ON again or if the CTL terminal is set to
"L" level and the VREF terminal voltage becomes 1.3V
(Min.) or less.
Undervoltage Lockout Circuit Block (UVLO)
In the transient state at normal power start-up or during
momentary drops in the power supply voltage, control IC
malfunction may be induced, which can lead to system
damage or deterioration. To prevent such malfunction, the
undervoltage lockout circuit detects decrease in internal
reference voltage level and turns OFF the output transistor
to set the dead time to 100% and maintain the CSCP terminal
to "L" level at the same time. If the power supply voltage
exceeds the threshold voltage of the undervoltage lockout
circuit, the system will restore itself.
Soft-Start Function
Soft-Start Circuit Block (CS)
By connecting capacitors for soft-start to the CS1 terminal
to CS4 terminal which are the non-inverted input terminals
of the error amplifier, inrush current at power start-up can
be prevented. Performing soft-start detection with the error
amplifier enables soft-start operation in a constant time
independent of DC/DC converter output load.
✱
Table 1 ON/OFF Setting Conditions for Each Channel
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94 FIND Vol.20 No.2 2002