+2.7V to +5.25V, Low-Power, 8-Channel,

Serial 10-Bit ADCs

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7

______________________________________________________________Pin Description

6k

DGND

DOUT

50pF

50pF

DGND

6k

DOUT

6k

DGND

DOUT

50pF

50pF

DGND

6k

DOUT

Figure 1. Load Circuits for Enable Time

Figure 2. Load Circuits for Disable Time

REFADJ

12

Serial-Strobe Output. In internal clock mode, SSTRB goes low when the MAX148/MAX149 begin the

A/D conversion, and goes high when the conversion is finished. In external clock mode, SSTRB pulses

high for one clock period before the MSB decision. High impedance when CS is high (external clock

mode).

SSTRB

16

Serial-Data Input. Data is clocked in at SCLK’s rising edge.

DIN

17

Active-Low Chip Select. Data will not be clocked into DIN unless CS is low. When CS is high, DOUT is

high impedance.

CS

18

Serial-Clock Input. Clocks data in and out of serial interface. In external clock mode, SCLK also sets

the conversion speed. (Duty cycle must be 40% to 60%.)

SCLK

19

Reference-Buffer Output/ADC Reference Input. Reference voltage for analog-to-digital conversion.

In internal reference mode (MAX149 only), the reference buffer provides a 2.500V nominal output,

externally adjustable at REFADJ. In external reference mode, disable the internal buffer by pulling

VREF

11

Analog Ground

AGND

13

Digital Ground

DGND

14

Serial-Data Output. Data is clocked out at SCLK’s falling edge. High impedance when CS is high.

DOUT

15

Three-Level Shutdown Input. Pulling SHDN low shuts the MAX148/MAX149 down; otherwise, they are

fully operational. Pulling SHDN high puts the reference-buffer amplifier in internal compensation mode.

Letting SHDN float puts the reference-buffer amplifier in external compensation mode.

SHDN

10

Ground reference for analog inputs. COM sets zero-code voltage in single-ended mode. Must be

stable to ±0.5LSB.

COM

9

PIN

Sampling Analog Inputs

CH0–CH7

1–8

FUNCTION

NAME

Positive Supply Voltage

20