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LTC2460_15 Datasheet, PDF (7/22 Pages) Linear Technology – Ultra-Tiny, 16-Bit ADCs with 10ppm/C Max Precision Reference | |||
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LTC2460/LTC2462
Block Diagram
9 IN+
(IN)
10 INâ
(GND)
1
2
12
REFOUT
COMP
VCC
âΣ A/D
CONVERTER
â
INTERNAL
REFERENCE
DECIMATING
SINC FILTER
SPI
INTERFACE
3
CS
5
SCK
6
SDO
4
SDI
âΣ A/D
CONVERTER
INTERNAL
OSCILLATOR
REFâ
8
( ) PARENTHESIS INDICATE LTC2460
7,11,13 (DD PACKAGE) GND
24602 BD
Figure 1. Functional Block Diagram
Applications Information
Converter Operation
Converter Operation Cycle
The LTC2460/LTC2462 are low power, delta sigma, ana-
log to digital converters with a simple SPI interface (see
Figure 1). The LTC2462 has a fully differential input while
the LTC2460 is single-ended. Both are pin and software
compatible. Their operation is composed of three distinct
states: CONVERT, SLEEP/NAP, and DATA INPUT/OUTPUT.
The operation begins with the CONVERT state (see Fig-
ureâ¯2). Once the conversion is finished, the converter
automatically powers down (NAP) or under user control,
both the converter and reference are powered down
(SLEEP). The conversion result is held in a static register
while the device is in this state. The cycle concludes with
the DATA INPUT/OUTPUT state. Once all 16-bits are read
or an abort is initiated the device begins a new conversion.
The CONVERT state duration is determined by the LTC2460/
LTC2462 conversion time (nominally 16.6 milliseconds).
Once started, this operation can not be aborted except by a
low power supply condition (VCC < 2.1V) which generates
an internal power-on reset signal.
After the completion of a conversion, the LTC2460/LTC2462
enters the SLEEP/NAP state and remains there until the
chip select is LOW (CS = LOW). Following this condition,
the ADC transitions into the DATA INPUT/OUTPUT state.
POWER-ON RESET
CONVERT
SLEEP/NAP
NO
CS = LOW?
YES
DATA INPUT/OUTPUT
16TH FALLING
NO
EDGE OF SCK
YES
OR
24602 F02
CS = HIGH?
Figure 2. LTC2460/LTC2462 State Transition Diagram
While in the SLEEP/NAP state, when chip select input is
HIGH (CS = HIGH), the LTC2460/LTC2462âs converters
are powered down. This reduces the supply current by
approximately 50%. While in the Nap state the reference
remains powered up. In order to power down the reference
in addition to the converter, the user can select the SLEEP
24602fa
7
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