MAX1258 Maxim Integrated Products, MAX1258 Datasheet - Page 33

• Manufacturer Part Number: MAX1258
• Description: Multichannel ADCs/DACs
• Manufacturer: Maxim Integrated Products

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Table 21. DAC Power-Up and Power-Down Commands
Figures 6–9 illustrate the conversion timing for the
MAX1220–MAX1223/MAX1257/MAX1258. All 12-bit
conversion results are output in 2-byte format, MSB
first, with four leading zeros. Data appears on DOUT on
the falling edges of SCLK. Data is binary for unipolar
mode and two’s complement for bipolar mode and tem-
perature results. See Figures 3, 4, and 5 for input/out-
put and temperature-transfer functions.
Figure 3 shows the unipolar transfer function for single-
ended or differential inputs. Figure 4 shows the bipolar
transfer function for differential inputs. Code transitions
C3 C2 C1 C0
1
1
1
1
1
CONTROL
BITS
1
1
1
1
1
1
1
1
1
1
1 — — — — — — — — 0
1 — — — — — — — — 0
1 — — — — — — — — 1
1 — — — — — — — — 0
1 — — — — — — — — 1
12-Bit, Multichannel ADCs/DACs with FIFO,
______________________________________________________________________________________
Temperature Sensing, and GPIO Ports
ADC Transfer Functions
DATA BITS
Output-Data Format
D3 D2 D1 D0
0
1
0
0
1
1
0
0
0
1
X
X
X
X
X
DESCRIPTION
Power-Down 1
Power-Down 2
Power-Down 3
Power-Down 4
Power-Up
occur halfway between successive-integer LSB values.
Output coding is binary, with 1 LSB = V
(MAX1221/MAX1223/MAX1257) and 1 LSB = V
4096 (MAX1220/MAX1222/MAX1258) for unipolar and
bipolar operation, and 1 LSB = +0.125°C for tempera-
ture measurements. Bipolar true-differential results and
temperature-sensor results are available in two’s com-
plement format, while all others are in binary. See
Tables 6, 7, and 8 for details on which setting (unipolar
or bipolar) takes precedence.
In unipolar mode, AIN+ can exceed AIN- by up to
V
other by up to V
REF1
. In bipolar mode, either input can exceed the
Power up individual DAC buffers indicated by data
in DAC0 through DAC7. A one indicates the DAC
output is connected and active. A zero does not
affect the DAC’s present state.
Power down individual DAC buffers indicated by
data in DAC0 through DAC7. A one indicates the
DAC output is disconnected and high impedance.
A zero does not affect the DAC’s present state.
Power down individual DAC buffers indicated by
data in DAC0 through DAC7. A one indicates the
DAC output is disconnected and pulled to AGND
with a 1kΩ resistor. A zero does not affect the DAC’s
present state.
Power down individual DAC buffers indicated by
data in DAC0 through DAC7. A one indicates the
DAC output is disconnected and pulled to AGND
with a 100kΩ resistor. A zero does not affect the
DAC’s present state.
Power down individual DAC buffers indicated by
data in DAC0 through DAC7. A one indicates the
DAC output is disconnected and pulled to REF1 with
a 100kΩ resistor. A zero does not affect the DAC’s
present state.
REF1
/ 2.
FUNCTION
REF1
/ 4096
REF1
33
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