MITSUBISHI SEMICONDUCTORS <Standard Linear ICs>
M62212P/FP/GP
GENERAL PURPOSE DC-DC CONVERTER
2. FUNCTION DESCRIPION
1) Soft Start (The peripheral circuit is shown in Fig.1)
When the power is turned ON, input terminal IN is at 0V level. Therefore, the FB
terminal is fixed to High level. The DTC terminal goes up gradually starting from 0V
due to the internal charge current and the external C
DTC
.
When the level of DTC terminal reaches the lower limit of the triangular wave of the
oscillator, PWM comparator and the output circuit go into operation causing the output
voltage, "Vo" of the DC-DC converter to rise. The charge current is designed to be
approximately 45µA.
FB
DTC
1.0V
OSC
0.45V
OFF
External Tr collector
ON
Fig.2
2) DTC
The dead time control is set by installing a resistor between the DTC terminal and GND.
However, the DTC terminal serves as the short protection circuit also. Therefore, its set up
depends on whether the short protection circuit is used and not.
(When the short protection circuit is used)
At this time, the charge current for DTC is approximately 10µA . Therefore, R
DTC
should
be set to 40KΩ ~ 110KΩ.
(When the short protection circuit is not used)
At this time, the charge current for DTC is approximately 45µA. Therefore, R
DTC
is set to
12KΩÅ`25KΩ.
(5/8)
MITSUBISHI [ MITSUBISHI ELECTRIC SEMICONDUCTOR ]
