FA7711V Datasheet, PDF (22/25 Pages) Fuji Electric – FUJI Power Supply Control IC

FA7711V
（10）Setting of the output voltage of DC-DC
converter
Figure 16,17,18 shows the ways to set each
channel of the output voltage of DC-DC converter.
・Applications for each channels
Ch1 Buck, Inverting
Ch2 Buck, Boost, Inverting, Fly-back
Ch3 Buck, Boost, Inverting, Fly-back
In the case of a boost, a buck, or a fly-back circuit,
the output voltage can be calculated with:
For Ch1 (Fig.16,Fig.17)
Vout1 = ^{R10 + R11} ×V1
R11
For Ch2 (Fig.17,Fig.18)
Vout 2 = ^{R20 + R21}×V 2
R 21
For Ch3 (Fig.16,Fig.18)
Vout3 = ^{R30 + R31} ×V 3
R31
An inverting circuit, the output voltage can be
calculated with:
For Ch1 (Fig.18)
Vout1 = ^{R10 + R11} ×V1− ^R11 ×VREF
R10
R10
For Ch2 (Fig.16)
Vout 2 = ^{R20 + R21} ×V 2 − ^R21 ×VREF
R 20
R 20
For Ch3 (Fig.17)
Vout 3 = ^{R30 + R31} ×V 3 − ^R31 ×VREF
R30
R30
The ratio of resistance can be calculated with:
R10 ₌ VREF −V1
R11 Vout1+V1
(Use the absolute value of Vout voltage)
(The same Vout2 and Vout3 as Vout1)
RREF2 RREF1
*
Vout1
R10
R11
VREF
R20
R21
Vout3
Vout2
R30
R31
4
VREF
V1 ₆ IN1+
7 ^IN1-
8 ^FB1
Er.AMP1 ^{OUT1 12}
V2 ₂₁ IN2+
20 ^IN2-
19 ^FB2
Er.AMP2 OUT2 13
VREF
SEL2 5
V3 ₂₄ IN3+
23 ^IN3-
22 ^FB3
Er.AMP3 OUT3 15
SEL3 3
RREF6 RREF5
RREF4 RREF3 V3
RREF2 RREF1 ^V2
V1
Vout1
R10
R11
Vout2
R20
R21
VREF
R30
R31
Vout3
4
VREF
6 ^IN1+
7 ^IN1-
8 ^FB1
Er.AMP1 ^{OUT1 12}
21 ^IN2+
20 ^IN2-
19 ^FB2
Er.AMP2
OUT2 13
VREF
SEL2 5
24 ^IN3+
23 ^IN3-
22 ^FB3
Er.AMP3 OUT3 15
VREF
SEL3 3
RREF6 RREF5
RREF4_V2RREF3 ^V3
RREF2 RREF1
V1
VREF
R10
R11
Vout2
Vout1
R20
R21
Vout3
R30
R31
4
VREF
6 ^IN1+
7 ^IN1-
Er.AMP1 ^{OUT1 12}
8 ^FB1
21 ^IN2+
20 ^IN2-
19 ^FB2
Er.AMP2 OUT2 13
SEL2 5
24 ^IN3+
23 ^IN3-
22 ^FB3
Er.AMP3 OUT3 15
VREF
SEL3 3
Vout1
Vout2
Vout3
Fig.16
Vout1
Vout2
Vout3
Fig.17
Vout1
Vout2
Vout3
Fig.18
Fuji Electric Systems Co., Ltd.
AN-060E Rev.1.0
22
Jun-2010
http://www.fujielectric.co.jp/fdt/scd/