BD95710MUV ROHM Electronics, BD95710MUV Datasheet - Page 10

• Manufacturer Part Number: BD95710MUV
• Description: 2phase Switching Regulator Controllers for Graphic Card
• Manufacturer: ROHM Electronics

6. Setting output voltage
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BD95710MUV
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7. Frequency Setting Resistance
The output voltage is REFIN/EN = VOUT when VOUT is tied to the FB directly. The range of VOUT is 0.4V ~ 3.3V.
0.6V
The output voltage is calculated as follow when resistor divider network is connected between the FB and VOUT.
REFIN/EN set 5Vcc.
The Frequency at steady state is determined by resistance value connected to RT pin.
But actual PHASE rising time and falling time are factored in due to the external MOSFET gate capacity or switching speed.
As a result, On-Time increases.
The frequency is determined by the following formula.
Consequently, total frequency becomes lower than the formula above.
On-Time increases by Dead Time on the condition of zero cross point of inductor current. And also switching frequency
increases as the output current increases due to the fixed On-Time and the influence of conduction loss.
It is recommended that switching frequency be checked on large current condition (at the point where the inductor current
doesn’t become reversed from Vout).
REFIN/EN
FB
FB
BUSEN
f [Hz]=
Ton =
BUSEN
CONTROLLA
CONTROLLA
H
H
3
Reg
3
10
Reg
VOUT
VIN
2×BUSEN
-12
TM
TM
×REFIN/EN×R
Vout =
×
Ton
1
R1+R2
R
S
R2
R
S
RT
・・・(13)
+ 170×10
x 0.6 [V]・・・(12)
Q
10/20
Q
-9
Ton : ON TIME
Circuit
Driver
Circuit
Driver
V
V
IN
IN
Technical Note
2009.04 - Rev.B
R1
R2
VOUT
VOUT