ltc1598l Linear Technology Corporation, ltc1598l Datasheet - Page 10

• Manufacturer Part Number: ltc1598l
• Description: 4- And 8-channel, 3v Micropower Sampling 12-bit Serial I/o A/d Converters
• Manufacturer: Linear Technology Corporation

LTC1594L/LTC1598L
APPLICATIONS
OVERVIEW
The LTC1594L/LTC1598L are 3V micropower, 12-bit
sampling A/D converters that feature 4- and 8-channel
multiplexers respectively. They typically draw only 160 A
of supply current when sampling at 10.5kHz. Supply
current drops linearly as the sample rate is reduced (see
Supply Current vs Sample Rate). The ADCs automatically
power down when not performing conversions, drawing
only leakage current. The LTC1594L is available in a
16-pin narrow SO package and the LTC1598L is pack-
aged in a 24-pin SSOP. Both devices operate on a single
supply from 2.7V to 3.6V.
The LTC1594L/LTC1598L contain a 12-bit, switched-
capacitor ADC, sample-and-hold, serial port and an
external reference input pin. In addition, the LTC1594L
has a 4-channel multiplexer and the LTC1598L provides
an 8-channel multiplexer (see Block Diagram). They can
measure signals floating on a DC common mode voltage
10
CSMUX = CSADC = CS
COM = GND
MUXOUT
ADCIN =
CH0 TO
D
CH7
CLK
OUT
D
U
IN
INFORMATION
U
Figure 1. LTC1594L/LTC1598L Operating Sequence Example: CH2, GND
EN
D2
Hi-Z
D1
W
D0
*AFTER COMPLETING THE DATA TRANSFER, IF FURTHER CLOCKS ARE APPLIED WITH CS LOW,
THE ADC WILL OUTPUT LSB-FIRST DATA THEN FOLLOWED WITH ZEROS INDEFINITELY
t
SMPL
t
ON
t
suCS
U
NULL
BIT
B11
B10
B9
t
CYC
and can operate with reduced spans to 1.5V. Reducing
the spans allow them to achieve 366 V resolution.
The LTC1594L/LTC1598L provide separate MUX output
and ADC input pins to form an ideal MUXOUT/ADCIN
loop which economizes signal conditioning. The MUX
and ADC of the devices can also be controlled individually
through separate chip selects to enhance flexibility.
SERIAL INTERFACE
For this discussion, we will assume that CSMUX and
CSADC are tied together and will refer to them as simply
CS, unless otherwise specified.
The LTC1594L/LTC1598L communicate with the micro-
processor and other external circuitry via a synchronous,
half duplex, 4-wire interface (see Operating Sequences in
Figures 1 and 2).
DON’T CARE
B8
B7
t
CONV
B6
B5
B4
B3 B2
B1 B0*
Hi-Z
1594F/98F F01
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