MAX152 Maxim, MAX152 Datasheet - Page 8

• Manufacturer Part Number: MAX152
• Description: +3V / 8-Bit ADC with 1A Power-Down
• Manufacturer: Maxim

A minimum acquisition time (t P ) is required from INT
going low to the start of another conversion (WR going
low).
Options for reading data from the converter include the
following:
The µP waits for the INT output to go low before read-
ing the data (Figure 4). INT goes low after the rising
edge of WR, indicating that the conversion is complete
and the result is available in the output latch. With CS
low, data outputs D0-D7 can be accessed by pulling
RD low. INT is then reset by the rising edge of CS or
RD.
An external method of controlling the conversion time is
shown in Figure 5. The internally generated delay
t INTL varies slightly with temperature and supply volt-
age, and can be overridden with RD to achieve the
fastest conversion time. RD is brought low after the ris-
ing edge of WR, but before INT goes low. This com-
pletes the conversion and enables the output buffers
(D0-D7) that contain the conversion result. INT also
goes low after the falling edge of RD and is reset on the
rising edge of RD or CS. The total conversion time is
therefore: t CWR = t WR (600ns) + t RD (800ns) + t ACC1
(400ns) = 1800ns.
Besides the two standard WR-RD mode options, stand-
alone operation can be achieved by connecting CS
and RD low (Figure 6). A conversion is initiated by
pulling WR low. Output data can be read by either
edge of the next WR pulse.
+3V, 8-Bit ADC with 1µA Power-Down
Figure 6. Stand-Alone Mode Timing (
Fastest Conversion: Reading Before Delay
8
D0-D7
_______________________________________________________________________________________
WR
INT
OLD DATA
t WR
t IHWR
t INTL
Stand-Alone Operation
Using Internal Delay
CS
t P
=
NEW DATA
RD
t ID
= 0) (MODE = 1)
Figure 7a. Power Supply as Reference
Figure 7b. External Reference, +2.5V Full Scale
Figure 7c. Input Not Referenced to GND
Figure 7d. An N-channel MOSFET switches off the reference
load during power-down.
*CURRENT PATH MUST STILL
EXIST FROM V IN - TO GND.
+3V
+3V
0.1µF
PWRDN
4.7
µF
+3V
0.1µF
+3V
4.7µF
0.1
µF
1
3
8
4
LM10
4.7µF
V IN-
7
MAX872
V IN +
V IN -
MTD3055EL
V IN +
V IN -
6
2
1.2V
2.2µF
C1
+2.5V
0.1µF
V IN +
12
11
10
20
1
0.1
µF
+
20
12
11
V IN
GND
V DD
VREF+
VREF-
N
VREF-
V DD
VREF+
VREF-
PWRDN
V DD
VREF+
MAX152
12
10
20
11
MAX152
GND
MAX152
1
0.1µF
10
V IN
GND
V DD
VREF+
VREF-
V IN
1
MAX152