njw4800 New Japan Radio Co.,Ltd, njw4800 Datasheet - Page 13

• Manufacturer Part Number: njw4800
• Description: 30v/4a Half Bridge Driver
• Manufacturer: New Japan Radio Co.,Ltd

The bootstrap condenser generates the power supply voltage of V
gate of the high side SW. As Shown as Fig5 in detail.
The internal counter decides the bootstrap condenser Charge and Discharge time.
It can be used as generating of the voltage for the bootstrap or a power supply voltage for other device(s). You should
connect capacitor (C
drooping characteristic type. It has drooping characteristic at over current protection function.
stopped. The Fault signal is output simultaneously from the FLT terminal. In order to return SW operation, you should
make chip surface temperature (Junction Temperature: Tj) below the 150°C*.
positive use. You should make sure to operate inside the junction temperature range rated. (* Design value)
Ver.2010-09-29
Regulator
5V
Boot Strap
In order to drive the gate of the high side SW, the voltage that is higher than power supply voltage is necessary.
You should connect bootstrap condenser larger than C
A capacitor discharge time (t
A capacitor charge time (t
Built-in Regulator
The REG Terminal outputs Reference Voltage (5V).
This regulator current capability (I
Thermal Shut Down Function
When NJW4800 chip temperature exceeds the 170°C, internal thermal shutdown circuit operates and SW function is
This function is a circuit to prevent IC at the high temperature from malfunctioning and is not something that urges
High-side SW: OFF
Low-side SW: ON
High Side
Gate Driver
Low Side
Gate Driver
V
REG
+
) larger than 1µF for stable regulator output.
VDD
OFF
ON
HPWM
HPWM
/ 128) for Low-side SW Minimum ON Time is 2.34µs (typ).
OREG
) for High-side SW Maximum ON Time is 300ms (typ).
OUT
) is 30mA (min) at (V
Fig5. High-side SW driven by Boot Strap
C
Power Line
Regulator Voltage
BS
CBS is
charged to 5V
BS
Regulator
5V
=0.1µF between BS Terminal and OUT Terminal.
REG1
×0.95). This regulator over current protection is a
+
+5V to BS terminal and it supplies the power to the
High-side SW: ON
Low-side SW: OFF
High Side
Gate Driver
Low Side
Gate Driver
V
+
VDD
ON
OFF
BS
OUT
NJW4800
C
Power Line
Regulator Voltage
BS
V
the BS terminal.
+
=5V is generated to
OUT becomes V+
voltage
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