+2.7V, Low-Power, Multichannel,

Serial 8-Bit ADCs

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17

Internal Reference

To use the MAX1110/MAX1111 with the internal refer-

ence, connect REFIN to REFOUT. The full-scale range

of the MAX1110/MAX1111 with the internal reference is

typically 2.048V with unipolar inputs, and ±1.024V with

bipolar inputs. The internal reference should be

bypassed to AGND with a 1µF capacitor placed as

close to the REFIN pin as possible.

Transfer Function

Table 4 shows the full-scale voltage ranges for unipolar

and bipolar modes. Figure 15 depicts the nominal, unipo-

lar I/O transfer function, and Figure 16 shows the bipolar

I/O transfer function when using a 2.048V reference.

Code transitions occur at integer LSB values. Output cod-

ing is binary, with 1LSB = 8mV (2.048V/256) for unipolar

operation and 1LSB = 8mV [(2.048V/2 - -2.048V/2)/256]

for bipolar operation.

POWERED UP

POWER-

DOWN

POWERED

UP

POWERED UP

DATA VALID

DATA VALID

DATA

INVALID

EXTERNAL

EXTERNAL

INTERNAL

SX XXXX 11

S

0 1

XX

X

X

X

X X XXX

S1 1

POWER-

DOWN

MODE

DOUT

DIN

CLOCK

MODE

SHDN

SETS EXTERNAL

CLOCK MODE

SETS EXTERNAL

CLOCK MODE

SETS POWER-

DOWN MODE

Figure 14a. Power-Down Modes, External Clock Timing Diagram

POWER-DOWN

POWERED

UP

POWERED UP

DATA VALID

DATA VALID

INTERNAL CLOCK MODE

SX XXXX 10

S

0 0

XX

X

X

X

S

MODE

DOUT

DIN

SETS INTERNAL

CLOCK MODE

SETS POWER-DOWN MODE

CONVERSION

CONVERSION

SSTRB

Figure 14b. Power-Down Modes, Internal Clock Timing Diagram