RT9602 データシートの表示（PDF） - Richtek Technology
部品番号
コンポーネント説明
メーカー
RT9602 Datasheet PDF : 11 Pages
| |||
RT9602
Power Dissipation vs. Frequency
800
CU=CL
700
=5nF
600
CU=CL=4nF
The method to improve the thermal transfer is to increase
the PCB copper area around the RT9602, first. Then, adding
a ground pad under IC to transfer the heat to the peripheral
of the board.
500
CU=CL=3nF
Power on Over-Voltage Protection Function
400
CU=CL=2nF
300
CU=CL=1nF
200
100
0
0
PVcc=Vcc=12V
100 200 300 400 500 600
Frequency (kHz)
Figure 5. Power Dissipation vs. Frequency (RT9602)
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 VCC and the phase signals are measured
on the VCC pin and the phase pin of RT9602. The LGATE
250
240
230
220
210
200
190
180
170
50
Power Dissipation vs. Frequency
signal is measured on the gate terminal of MOSEFET.
CU=CL=4nF
CU=CL
=5nF
CU=CL=2nF
CU=CL=1nF
VVcc >
PPEASE >
lLGATE >
CU=CL=3nF
RT9809-20CV
hrountCurrent >
Through
12V
100 150 200 250 300 350 400 450
Frequency(kHz)
Time (50ms)
Figure 7 High Side Direct Short
Figure 6. Power Dissipatin vs. Frequency, PVCC = 5V
The operating junction temperature can be calculated from
the power dissipation curves (Figure 5 and Figure 6).
Assume the RT9602’ s PVCC = VCC=12V, operating
frequency is 200kHz, and the CU=CL=1.5nF which emulate
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 θJA is
127.67°C/W, the operating junction temperature is
calculated as:
TJ = 127.67°C/W x 500mW+ 25°C = 88.84°C (11)
where the 25°C is the ambient temperature.
VVcc >
PPEAS >
lLGATE >
lVCORE>
Time (50ms)
Figure 8. High Side Direct Short
DS9602-08 March 2007
www.richtek.com
9
Share Link: 