RT9602GS RICHTEK [Richtek Technology Corporation], RT9602GS Datasheet - Page 9

• Manufacturer Part Number: RT9602GS
• Description: Dual Channel Synchronous-Rectified Buck MOSFET Driver
• Manufacturer: RICHTEK [Richtek Technology Corporation]

DS9602-08 March 2007
The operating junction temperature can be calculated from
the power dissipation curves (Figure 5 and Figure 6).
Assume the RT9602
frequency is 200kHz, and the C
the input capacitances of the high side and low side power
MOSFETs. From Figure 5, the power dissipation is 500mW.
In RT9602, the package thermal resistance θ
127.67°C/W, the operating junction temperature is
calculated as:
T
where the 25°C is the ambient temperature.
Figure 6. Power Dissipatin vs. Frequency, PVCC = 5V
J
Figure 5. Power Dissipation vs. Frequency (RT9602)
= 127.67°C/W x 500mW+ 25°C = 88.84°C
250
240
230
220
210
200
190
180
170
800
700
600
500
400
300
200
100
0
50
0
C
=
5nF
U
=C
Power Dissipation vs. Frequency
Power Dissipation vs. Frequency
100
L
100
C
U
=C
C
=5nF
150
U
=C
L
=1nF
’
200
L
C
s PVCC = V
Frequency (kHz)
200
Frequency(kHz)
U
C
=C
U
=C
L
=4nF
L
U
300
=2nF
250
=C
C
C
U
U
L
=C
=C
=1.5nF which emulate
300
L
L
CC
=3nF
400
=3nF
C
=12V, operating
U
PV
=C
350
RT9809-20CV
cc
C
L
=2nF
=V
U
C
500
=C
U
cc
=C
400
L
=12V
=4nF
L
=1nF
(11)
JA
600
450
is
hrount
P
The method to improve the thermal transfer is to increase
the PCB copper
a ground pad under IC to transfer the heat to the peripheral
of the board.
Power on Over-Voltage Protection Function
The RT9602 provides a protect function which can avoid
some short condition happened before power on.
The following discussion about the power on over-voltage
protection function of RT9602 is based on the experiments
of the high side MOSFET directly shorted to 12V. The test
circuit as shown in the typical application circuit (with
RT9241A/B dual-channel synchronous-rectified buck
controller) the V
on the VCC pin and the phase pin of RT9602. The LGATE
signal is measured on the gate terminal of MOSEFET.
Current
l
Through
PEASE
LGATE
P
lLGATE
V
l
PEAS
V
Vcc
V
12V
CORE
Vcc
>
>
>
>
>
>
>
>
Figure 7 High Side Direct Short
Figure 8. High Side Direct Short
area around the RT9602, first. Then, adding
CC
and the phase signals are measured
Time (50ms)
Time (50ms)
RT9602
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