MB39A102_05 Datasheet, PDF (20/32 Pages) Tyco Electronics – 4-ch DC/DC Converter IC

MB39A102
■ OPERATION EXPLANATION WHEN CTL TURNING ON AND OFF
When CTL is turned on, internal reference voltage VR and VREF generate. When VREF exceeds threshold
voltage (VTH) of UVLO (under voltage lockout protection circuit), UVLO 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 UVLO fall below each reset voltage (VRST),
UVLO operates and output Drive circuit of each channel is forcibly done the operation stop, and makes the output
off state.
When period to reaching to 2.0 V by VREF voltage after UVLO are released by turning on CTL (refer to a in
“• Timing Chart”), and VREF decreases from 2.0 V after turning off CTL and the period until do the operation
of UVLO (refer to a’ in “• Timing Chart”), the bias voltage and the bias current in IC do not reach a prescribed
value because VREF which is the reference voltage does not reach 2.0 V, and the speed of response for IC has
decreased.
Note : Moreover, when it does the turning on and off of the input sudden change, the load sudden change, IC
cannot conform 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 CH4 output Drive circuit
H : Possible to operate
L : Forcibly stop
To CS1 to CS4 charge/
discharge circuit
H : Possible to charge
L : Forcibly discharge
UVLO
H : UVLO release
bias
ErrorAmp Reference
1.24 V
VREF
VR
Power
ON/OFF
CTL
VCC
5
CTL
6
7
VREF
20