mx7828 Maxim Integrated Products, Inc., mx7828 Datasheet - Page 8

• Manufacturer Part Number: mx7828
• Description: Cmos, High-speed, 8-bit Adc With 4- Or 8-channel Multiplexer
• Manufacturer: Maxim Integrated Products, Inc.

The V
zero and the full-scale of the ADC. In other words, the
voltage at V
duces an output code of all zeros, and the voltage at
V
code of all ones (Figure 7).
Figure 8 shows some possible reference configura-
tions. For the MAX154/MAX158, a 0.01µF bypass
capacitor to GND should be used to reduce the high-
frequency output impedance of the internal reference.
Larger capacitors should not be used, as this degrades
the stability of the reference buffer. The 2.5V reference
output is with respect to the GND pin.
A 47µF electrolytic and 0.1µF ceramic capacitor should
be used to bypass the V
tors must have minimum lead length, since excess lead
length may contribute to conversion errors and instability.
If the reference inputs are driven by long lines, they
should be bypassed to GND with 0.1µF capacitors at
the reference input pins.
CMOS, High-Speed, 8-Bit ADCs
with Multiplexer
_____________Analog Considerations
Figure 6. Mode 1 Timing Diagram
8
REF
CHANNEL
ADDRESS
ANALOG
_______________________________________________________________________________________
+ is equal to input voltage that produces an output
DATA
REF
RDY
INT
CS
RD
+ and V
REF
t
CSS
- is equal to the input voltage that pro-
REF
- inputs of the converter define the
t
AS
ADDR
VALID
t
RDY
DD
t
ACCI
t
AH
pin to GND. These capaci-
Reference and Input
t
RD
DATA
OLD
t
INTH
Bypassing
t
CRD
t
DH
t
CSH
Figure 7. Transfer Function
V
11111111
11111110
11111101
00000011
00000010
00000001
00000000
REF
-
t
CSS
OUTPUT
CODE
t
P
t
1
AS
2
VALID
ADDR
t
t
RDY
ACCI
t
3
AH
AIN INPUT VOLTAGE
(IN TERMS OF LSBs)
t
RD
1LSB = F8 = V
DATA
NEW
FULL-SCALE
TRANSITION
256
t
INTH
t
DH
REF
t
CSH
+ - V
FS–1LSB
256
REF
-
FS
V
REF
+