BD95710MUV ROHM Electronics, BD95710MUV Datasheet - Page 11

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

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BD95710MUV
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8. UVLO
BD95710MUV has function to detect input UVLO voltage in each VCC, 5VCC, and BUSEN for output voltage to start up.
If all these inputs go beyond their own UVLO threshold voltage, the soft start function kicks in.
These threshold voltages have their own hysteresis voltage to avoid faulty operation caused by input noises and glitchs.
9. Current Phase Balance
BD95710MUV keeps the current phase balance between coil current IL1 and IL2 by controlling the status ΔVcs1 = Δ
Vcs2.And for that, it is needed to meet the reference formula below.
For detecting the value of ΔVcs1 or ΔVcs2 exactly, it is also needed to meet the formula below.
PHA
ΔVcs1
BUSEN
VCC
5VCC
VOUT
Output OFF
CSP1
CS1-
r
I
L1 = L2 (RL1 =RL2), r1 = r2, C1 = C2. ・・・(14)
RL1 =
Vcs+
VIN_BUS
⊿Vcs
⊿V
L1
r1
I
r1×C1
VCCUVLO
L1
IL1
RL1
Vcs-
C1
r1
r2
Tss
・・・(15)
ΔVcs2
5VCCUVLO
Output OFF
Co
However, Vcs+ and Vcs- are fed a small current from current sense amplifier,
and this current causes a slight difference in the actual value obtained from
formula (15). Refer to formula (16) below:
⊿Vcs=⊿V- I×r ・・・(16)
This difference can be compensated for by adding resistor r2.
⊿Vcs=(⊿V- I x r) + I x r2・・・(17)
To eliminate the difference, choose r2 to have the same value as r.
⊿Vcs=⊿V・・・(18)
Hys
CSP2
CSN2
5
Tss
VCC
VIN_EXT
L2
r2
Output OFF
IL2
VCCUVLO
11/20
RL2
C2
r2
Tss
Hysteresiwindow Hys
Co
V
OUT
BUSENUVLO
Output OFF
VCC
Hys
BUSEN
Tss
VCCUVLO
（Tss: Soft Start Time）
Output OFF
Technical Note
2009.04 - Rev.B