LTC2431CMS#PBF Linear Technology, LTC2431CMS#PBF Datasheet - Page 17

• Manufacturer Part Number: LTC2431CMS#PBF
• Description: IC ADC 20BIT DIFFINPUT/REF10MSOP
• Manufacturer: Linear Technology

Specifications of LTC2431CMS#PBF

• Number Of Bits: 20
• Sampling Rate (per Second): 7.5
• Data Interface: MICROWIRE™, Serial, SPI™
• Number Of Converters: 2
• Power Dissipation (max): 1mW
• Voltage Supply Source: Single Supply
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 10-TFSOP, 10-MSOP (0.118", 3.00mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

APPLICATIO S I FOR ATIO
the device aborts the data output state and immediately
initiates a new conversion. This is useful for systems not
requiring all 24 bits of output data, aborting an invalid con-
version cycle or synchronizing the start of a conversion.
External Serial Clock, 2-Wire I/O
This timing mode utilizes a 2-wire serial I/O interface. The
conversion result is shifted out of the device by an exter-
nally generated serial clock (SCK) signal, see Figure 7. CS
may be permanently tied to ground, simplifying the user
interface or isolation barrier.
The external serial clock mode is selected at the end of the
power-on reset (POR) cycle. The POR cycle is concluded
approximately 1ms after V
to SCK at this time determines if SCK is internal or external.
SCK must be driven LOW prior to the end of POR in order
to enter the external serial clock timing mode.
Since CS is tied LOW, the end-of-conversion (EOC) can be
continuously monitored at the SDO pin during the convert
and sleep states. EOC may be used as an interrupt to an
external controller indicating the conversion result is
ready. EOC = 1 while the conversion is in progress and
(EXTERNAL)
SDO
SCK
CS
SLEEP
OUTPUT
DATA
BIT 0
EOC
U
CONVERSION
Hi-Z
TEST EOC
U
CC
SLEEP
exceeds 2V. The level applied
Hi-Z
(OPTIONAL)
Figure 6. External Serial Clock, Reduced Data Output Length
TEST EOC
W
ANALOG INPUT RANGE
SLEEP
–0.5V
Hi-Z
REF
0.1V TO V
REFERENCE
BIT 23
TO 0.5V
EOC
VOLTAGE
U
1 F
2.7V TO 5.5V
REF
CC
BIT 22
V
REF
REF
IN
IN
GND
CC
+
–
LTC2430/
LTC2431
+
–
BIT 21
SDO
SIG
SCK
EOC = 0 once the conversion ends. On the falling edge of
EOC, the conversion result is loaded into an internal static
shift register. Data is shifted out the SDO pin on each
falling edge of SCK enabling external circuitry to latch data
on the rising edge of SCK. EOC can be latched on the first
rising edge of SCK. On the 24th falling edge of SCK, SDO
goes HIGH (EOC = 1) indicating a new conversion has
begun.
Internal Serial Clock, Single Cycle Operation
This timing mode uses an internal serial clock to shift out
the conversion result and a CS signal to monitor and
control the state of the conversion cycle, see Figure 8.
In order to select the internal serial clock timing mode, the
serial clock pin (SCK) must be floating (Hi-Z) or pulled
HIGH prior to the falling edge of CS. The device will not
enter the internal serial clock mode if SCK is driven LOW
on the falling edge of CS. An internal weak pull-up resistor
is active on the SCK pin during the falling edge of CS;
therefore, the internal serial clock timing mode is auto-
matically selected if SCK is not externally driven.
CS
F
O
DATA OUTPUT
BIT 20
MSB
3-WIRE
SPI INTERFACE
V
CC
= 50Hz REJECTION
= EXTERNAL OSCILLATOR
= 60Hz REJECTION
BIT 19
LTC2430/LTC2431
BIT 9
BIT 8
CONVERSION
Hi-Z
TEST EOC
2431 F06
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