m51996ap Renesas Electronics Corporation., m51996ap Datasheet - Page 34

• Manufacturer Part Number: m51996ap
• Description: Switching Regulator Control
• Manufacturer: Renesas Electronics Corporation.

M51996AP/AFP
Driver Circuit for Bipolar Transistor
When the bipolar transistor is used instead of MOS FET, the base current of bipolar transistor must be sinked by the
negative base voltage source for the switching-off duration, in order to make the switching speed of bipolar transistor
fast one.
In this case, over current can not be detected by detecting resistor in series to bipolar transistor, so it is recommended to
use the CT (current transformer).
For the low current rating transistor, type M51996A can drive it directly as shown in figure 40.
Attention for Heat Generation
The maximum ambient temperature of type M51996A is 85 C, however the ambient temperature in vicinity of the IC
is not uniform and varies place by place, as the amount of power dissipation is fearfully large and the power dissipation
is generated locally in the switching regulator.
So it is one of the good idea to check the IC package temperature.
The temperature difference between IC junction and the surface of IC package is 15 C or less, when the IC junction
temperature is measured by temperature dependency of forward voltage of pin junction, and IC package temperature is
measured by "thermo-viewer", and also the IC is mounted on the “phenol-base” PC board in normal atmosphere.
So it is concluded that the maximum case temperature (surface temperature of IC) rating is 120 C with adequate margin.
REJ03D0836-0201 Rev.2.01 Nov 14, 2007
Page 34 of 35
(−2 V to −5 V)
−V
Figure 39 Driver Circuit Diagram (1) for Bipolar Transistor
Figure 40 Driver Circuit Diagram (2) for Bipolar Transistor
V
CC
SS
GND
V
CC
M51996A
GND
Collector
V
Emitter
CC
M51996A
V
OUT
Collector
Emitter
V
OUT
Bipolar
transistor