MAX1257BETM+ Maxim Integrated Products, MAX1257BETM+ Datasheet - Page 35

• Manufacturer Part Number: MAX1257BETM+
• Description: IC ADC/DAC 12BIT 48-TQFN
• Manufacturer: Maxim Integrated Products
• Type: ADC, DACr

Specifications of MAX1257BETM+

• Resolution (bits): 12 b
• Sampling Rate (per Second): 225k
• Data Interface: Serial
• Voltage Supply Source: Analog and Digital
• Voltage - Supply: 2.7 V ~ 3.6 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 48-TQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

scan is complete, EOC is pulled low and the results are
available in the FIFO. Wait until EOC goes low before
pulling CS low to communicate with the serial interface.
EOC stays low until CS or CNVST is pulled low again. A
temperature-conversion result, if requested, precedes
all other FIFO results.
Do not issue a second CNVST signal before EOC goes
low; otherwise, the FIFO can be corrupted. Wait until all
conversions are complete before reading the FIFO. SPI
communications to the DAC and GPIO registers are per-
mitted during conversion. However, coupled noise may
result in degraded ADC signal-to-noise ratio (SNR).
Figure 6. Clock Mode 00—After writing a command byte, set CNVST low for at least 40ns to begin a conversion.
Figure 7. Clock Mode 01—After writing a command byte, request multiple conversions by setting CNVST low for each conversion.
CNVST
DOUT
SCLK
CNVST
EOC
SCLK
DOUT
CS
EOC
CS
(ACQUISITION 1)
(CONVERSION 1)
12-Bit, Multichannel ADCs/DACs with FIFO,
t
______________________________________________________________________________________
DOV
(ACQUISITION 2)
t
Temperature Sensing, and GPIO Ports
CSW
(UP TO 514 INTERNALLY CLOCKED ACQUISITIONS AND CONVERSIONS)
t
RDS
(CONVERSION 2)
MSB1
MSB1
In clock mode 01, conversions are requested one at a
time using CNVST and performed automatically using
the internal oscillator. See Figure 7 for clock mode 01
timing after a command byte is issued.
Setting CNVST low begins an acquisition, wakes up the
ADC, and places it in track mode. Hold CNVST low for
at least 1.4µs to complete the acquisition. If reference
mode 00 or 10 is selected, an additional 45µs is
required for the internal reference to power up. If a tem-
perature measurement is being requested, reference
power-up and temperature measurement is internally
timed. In this case, hold CNVST low for at least 40ns.
Internally Timed Conversions with CNVST
Externally Timed Acquisitions and
LSB1
ADC Conversions in Clock Mode 01
LSB1
MSB2
MSB2
35