ES51963
4 1/2 DMM
Testing Circuit
820k
0.1u
9V
5~6V
+
-
Regulator
180k
(-2.5V~-3V)
(+2.5V~+3V)
(2.5V)
LBATT
V+
V-
+
91k
10k
0.1u
0.1u
10u
(-1.23V)
-
V12
(-2.5V)
-
4.7u
AGND (0V)
+
-
+
4.7u
DGND
BUZout
BUZin
OSC1
AGND
Cref+
Cref-
Ref+
(0V)
Vcc
Vss
(-3V)
C1
0.22u/0.47u
4.7u
+
-
8051
serial
OSC2
C2
Ref-
EOC
SCLK
0.47u
33n
Caz
Cint
Buf
STATUS
100k
10k
Vcc(uP)
Rx
10n
10n
BufX10
CP-
CP+
PHin
-
V in
+
0.1u Vin-
100
1M
Signal
Vin+
1n
ES51963
Note: 1. Vin+, Vin- are differential inputs.
2. PHin is always reference to AGND.
3. Let the leakage current of CP+ and CP- as small as possible.
180k + 820k
4. LBATT : (2.5-1.23)×
= 7.06V
180k
5. Rx = 20~100Ω , which is used to compensate the internal resistor.
6. When external crystal is <800 kHz, we wuggest the C1 (6pF) and C2 (8~22pF) to
make it work.
18
2003/9/1
CYRUSTEK [ Cyrustek corporation ]
