HA17431 Hitachi Semiconductor, HA17431 Datasheet - Page 20

• Manufacturer Part Number: HA17431
• Description: Regarding the change of names mentioned in the document/ such as Hitachi Electric and Hitachi XX/ to Renesas Technology Corp.
• Manufacturer: Hitachi Semiconductor

HA17431 Series
AC characteristic determination: This refers to the determination of the gain frequency characteristic of
the shunt regulator as an error amplifier. Taking the configuration in figure 2, the error amplifier
characteristic is as shown in figure 3.
In Figure 3, the following formulas are obtained:
Gain
Corner frequencies
G
∆Vref/∆V
Rev.1, Sep. 2002, page 18 of 24
0
is the shunt regulator open-loop gain; this is given by the reciprocal of the reference voltage fluctuation
G
G
f
f
1
2
KA
1
2
= 1/(2π C
= 1/(2π C
, and is approximately 50 dB.
= G
=
R
R
0
5
3
≈ 50 dB to 60 dB (determined by shunt regulator)
1
1
G
R
5
0
)
R
Figure 3 HA17431 Error Amplification Characteristic
3
)
G
f
1
1
f
AC
* f
OSC
f
2
: PWM switching frequency
G
2
When R
f
OSC
When R
Frequency f (Hz)
5
= 0
5
≠ 0