![Sino Wealth SH69K55A Manual Download Page 45](http://html1.mh-extra.com/html/sino-wealth/sh69k55a/sh69k55a_manual_1283061045.webp)
SH69P55A/K55A
45
Application Notes:
When the External reference voltage is selected, the SH69P55A/69K55A ADC needs a little current, which is input into
SH69P55A/69K55A from the V
REF
pin to maintain the A/D normal running. The methods that show in figure 1 and figure 2 to
set up the External reference voltage are recommended. If the A/D Conversion Time is between 25
µ
s and 50
µ
s, a
capacitance (10
µ
F) can be added between the V
REF
pin and the GND pin to provide the current input into the
SH69P55A/69K55A from the V
REF
pin (figure 3). The method that shows in figure 4 also can set up the External reference
voltage but the current consume of the hole system will increase obviously (V
DD
= 5.0V, R1 + R2 = 500
Ω
, 10mA increases)
(the dashed frames in all the figures are 0.1
µ
F capacitances in order to reducing the disturbance in the V
REF
pin).
V
DD
V
DD
GND
V
REF
SH69P55A
/69K55A
2k
V
DD
V
DD
GND
V
REF
SH69P55A
/69K55A
Figure 1.
Figure 2.
V
DD
V
DD
GND
V
REF
R1
R2
SH69P55A
/69K55A
V
DD
V
DD
GND
V
REF
R1
R2
SH69P55A
/69K55A
Figure 3. (R1+R2
≧
50k
Ω
)
Figure
4.
(R1+R2
≦
500
Ω
)