MAX1274BETC+ Maxim Integrated Products, MAX1274BETC+ Datasheet - Page 10

IC ADC 12BIT 1.8MSPS 12-TQFN

MAX1274BETC+

Manufacturer Part Number
MAX1274BETC+
Description
IC ADC 12BIT 1.8MSPS 12-TQFN
Manufacturer
Maxim Integrated Products
Datasheet

Specifications of MAX1274BETC+

Number Of Bits
12
Sampling Rate (per Second)
1.8M
Data Interface
MICROWIRE™, QSPI™, Serial, SPI™
Number Of Converters
1
Power Dissipation (max)
45mW
Voltage Supply Source
Analog and Digital
Operating Temperature
-40°C ~ 85°C
Mounting Type
Surface Mount
Package / Case
12-WQFN Exposed Pad
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Upon initial power-up, the MAX1274/MAX1275 require a
complete conversion cycle to initialize the internal cali-
bration. Following this initial conversion, the part is ready
for normal operation. This initialization is only required
after a hardware power-up sequence and is not required
after exiting partial or full power-down mode.
To start a conversion, pull CNVST low. At CNVST’s
falling edge, the T/H enters its hold mode and a conver-
sion is initiated. SCLK runs the conversion and the data
can then be shifted out serially on DOUT.
Conversion-start and data-read operations are con-
trolled by the CNVST and SCLK digital inputs. Figures 1
and 5 show timing diagrams, which outline the serial-
interface operation.
1.8Msps, Single-Supply, Low-Power,
True-Differential, 12-Bit ADCs
Figure 5. Interface-Timing Sequence
Figure 6. SPI Interface—Partial Power-Down Mode
10
______________________________________________________________________________________
CNVST
MODE
DOUT
CNVST
SCLK
DOUT
SCLK
HIGH IMPEDANCE
t
Initialization After Power-Up
SETUP
0
and Starting a Conversion
1ST SCLK RISING EDGE
1
0
Serial Interface
2
Timing and Control
0
ONE 8-BIT TRANSFER
NORMAL
3
D11
4
D10
D11
D10
D9
POWER-MODE SELECTION WINDOW
D9
D8
D8
D7
8
DOUT GOES HIGH IMPEDANCE ONCE CNVST GOES HIGH
D7
CNVST MUST GO HIGH AFTER THE 3RD BUT BEFORE THE 14TH SCLK RISING EDGE
A CNVST falling edge initiates a conversion sequence;
the T/H stage holds the input voltage, the ADC begins
to convert, and DOUT changes from high impedance to
logic low. SCLK is used to drive the conversion
process, and it shifts data out as each bit of the conver-
sion is determined.
SCLK begins shifting out the data after the 4th rising
edge of SCLK. DOUT transitions t
SCLK’s rising edge and remains valid 4ns (t
after the next rising edge. The 4th rising clock edge
produces the MSB of the conversion at DOUT, and the
MSB remains valid 4ns after the 5th rising edge. Since
there are 12 data bits and 3 leading zeros, at least 16
rising clock edges are needed to shift out these bits.
For continuous operation, pull CNVST high between the
14th and the 16th SCLK rising edges. If CNVST stays
low after the falling edge of the 16th SCLK cycle, the
DOUT line goes to a high-impedance state on either
CNVST’s rising edge or the next SCLK’s rising edge.
D6
D5
D4
D3
PPD
D2
14
D1
t
ACQUIRE
D0
16
CONTINUOUS-CONVERSION
SELECTION WINDOW
DOUT
after each
DHOLD
)

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