MB39A103 Datasheet, PDF (21/33 Pages) List of Unclassifed Manufacturers – 4-Channel DC/DC Converter IC with Support for Low Voltage

MB39A103
■ OPERATION EXPLANATION WHEN CTL TURNING ON AND OFF
When CTL is turned on, internal reference voltage VR and VREF generate. When VREF exceeds each threshold
voltage (VTH1, VTH2) of UVLO1 and UVLO2 (under voltage lockout protection circuit), UVLO1 and UVLO2 are
released, and the operation of output Drive circuit of each channel becomes possible.
When CTL is off, VR and VREF fall. When VREF decreases and UVLO1 and UVLO2 fall below each reset
voltage (VRST1, VRST2), UVLO operates and output Drive circuit of each channel is forcibly done the operation
stop, and makes the output off state.
For the period to reach to 2.0 V by VREF voltage after UVLO1 and UVLO2 are released by turning on CTL (refer
to a and b in “• Timing Chart”) and the period when VREF decreases from 2.0 V after turning off CTL until UVLO1
and UVLO2 operate (refer to a’ and b’ in “• Timing Chart”), VREF which is the reference voltage does not reach
2.0 V. Therefore, the bias voltage and the bias current in IC do not reach a prescribed value, and the speed of
response for IC has decreased.
Note : For this reason, when the input sudden change and the load sudden change occur in this period, IC cannot
respond immediately and the output might overshoot.
Therefore, impress the voltage to CTL terminal by which the VREF terminal voltage never stays in the above-
mentioned period.
• CTL Block Equivalent Circuit
H : at SCP
SCP
To CH1 to CH3 output Drive circuit
H : Possible to operate
L : Forcibly stop
To CS1 to CS3 charge/discharge
circuit
H : Possible to charge
L : Forcibly discharge
UVLO2
UVLO1
H : UVLO release
bias
H : UVLO release
To CH4 output Drive circuit
H : Possible to operate
L : Forcibly stop
To CS4 charge/discharge circuit
ErrorAmp Reference
H : Possible to charge
L : Forcibly discharge
1.24 V
VCC
5
VREF
Power
VR
ON/OFF
CTL
CTL
6
7
VREF
21