MCP3301-I/P Microchip Technology, MCP3301-I/P Datasheet - Page 20

• Manufacturer Part Number: MCP3301-I/P
• Description: 13-Bit Differential Input, Low Power A/D Converter with SPI Serial Interface
• Manufacturer: Microchip Technology

MCP3301
7.2
Communication with the device is done using a stan-
dard SPI compatible serial interface. Initiating commu-
nication with the MCP3301 begins with the CS going
low. If the device was powered up with the CS pin low,
it must be brought high and back low to initiate commu-
nication. The device will begin to sample the analog
input on the first rising edge of CLK after CS goes low.
The sample period will end in the falling edge of the
second clock, at which time the device will output a low
null bit. The next 13 clocks will output the result of the
FIGURE 7-2:
FIGURE 7-3:
DS21700A-page 20
CLK
D
CS
D
OUT
CLK
CS
OUT
t
ACQ
Communicating with the MCP3301
* After completing the data transfer, if further clocks are applied with CS low, the ADC will output LSB first data, followed by zeros
indefinitely. See Figure below.
** t
node, leaving the CLK running to clock out the LSB-first data or zeros.
HI-Z
HI-Z
DATA
* After completing the data transfer, if further clocks are applied with CS low, the ADC will output zeros indefinitely.
** t
node, leaving the CLK running to clock out the LSB-first data or zeros.
Communication with MCP3301 (MSB first Format).
DATA
Communication with MCP3301 (LSB first Format).
: during this time, the bias current and the comparator power down and the reference input becomes a high impedance
t
t
ACQ
SUCS
t
: during this time, the bias current and the comparator power down and the reference input becomes a high impedance
SUCS
NULL
BIT
NULL
SB
BIT
B11 B10
SB
B11 B10 B9
B9
B8
t
CONV
B7
B6
B8
B5
t
SAMPLE
B7
t
CONV
B4
B6
B3
B2
B5
B1
t
B4
SAMPLE
conversion with the sign bit first, followed by the 12
remaining data bits, as shown in Figure 7-2. Data is
always output from the device on the falling edge of the
clock. If all 13 data bits have been transmitted and the
device continues to receive clocks while the CS is held
low, the device will output the conversion result LSB
first, as shown in Figure 7-3. If more clocks are pro-
vided to the device while CS is still low (after the LSB
first data has been transmitted), the device will clock
out zeros indefinitely.
B0
B3
B1
B2
B2
B3
B1 B0
t
CSH
B4
B5
*
t
DATA
t
Power Down
DATA
B6
**
**
Power
Down
HI-Z
B7
2001 Microchip Technology Inc.
B8
B9 B10
NULL
BIT
SB B11 B10 B9
B11
t
CSH
SB
*
HI-Z