bd9745ekn ROHM Co. Ltd., bd9745ekn Datasheet - Page 19

• Manufacturer Part Number: bd9745ekn
• Description: 7-channel Switching Regulator Controller For Digital Camera
• Manufacturer: ROHM Co. Ltd.

５.) Built-in Pch FET(CH1～4,CH67),the drop of current ability in low battery voltage situation
６.) Setting the oscillator frequency.
100
0.1
10
1
The ON resistance of the built-in Pch FET increase because the FET operates in the saturation region below VGS=1.3V.
Therefore when CH6, 7 step-up converter or step-down channel from a battery is used below 1.8V, the drop is must be considered.
If operating condition below 1.8V should be anticipated, it is recommended that the converter is formed from other channel’s output and is not used
high side switch.
The oscillator frequency is user-adjustable by varying the resistor connected to RT (29pin). The CH1～4 frequency is set 1.2MHz to connect 62kΩ,and
the RT value is inverse proportional relation to the frequency.
The CH5～7 frequency is set half value of the CH1～4 frequency.
Fig.12 shows the relation the RT value and the frequency.
0
1
Gate - Source Voltage V
2
a. CH４
10000
1000
Recommended region
100
3
10
GS
I
DS
[V]
=200mA
Fig - 11 Built-in PMOS ON resistance - V
4
Fig -12 Oscillator frequency – RT resister (EX)
CH5～6
5
RT [kΩ]
CH1～4
100
REV. D
100
0.1
10
1
0
1
GS
b. CH７ Highside Switch
Gate - Source Voltage V
1000
2
Recommended region
3
GS
[V]
I
DS
=200mA
4
5
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