LTC1857/LTC1858/LTC1859
7
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For more information www.linear.com/LTC1857
TYPICAL PERFORMANCE CHARACTERISTICS
LTC1859 Power Supply
Feedthrough vs Ripple Frequency
Supply Current vs Supply Voltage
Supply Current vs Temperature
COM (Pin 1): Common Input. This is the reference point
for all single-ended inputs. It must be free of noise and is
usually connected to the analog ground plane.
CH0 (Pin 2): Analog MUX Input.
CH1 (Pin 3): Analog MUX Input.
CH2 (Pin 4): Analog MUX Input.
CH3 (Pin 5): Analog MUX Input.
CH4 (Pin 6): Analog MUX Input.
CH5 (Pin 7): Analog MUX Input.
CH6 (Pin 8): Analog MUX Input.
CH7 (Pin 9): Analog MUX Input.
MUXOUT
+
(Pin 10): Positive MUX Output. Output of the ana-
log multiplexer. Connect to ADC
+
for normal operation.
MUXOUT
–
(Pin 11): Negative MUX Output. Output of the ana-
log multiplexer. Connect to ADC
–
for normal operation.
ADC
+
(Pin 12): Positive Analog Input to the Analog-to-
Digital Converter.
ADC
–
(Pin 13): Negative Analog Input to the Analog-to-
Digital Converter.
AGND1 (Pin 14): Analog Ground.
V
REF
(Pin 15): 2.5V Reference Output. Bypass to analog
ground with a 1µF tantalum capacitor.
REFCOMP (Pin 16): Reference Buffer Output. Bypass to
analog ground with a 10µF tantalum and a 0.1µF ceramic
capacitor. Nominal output voltage is 4.096V.
AGND2 (Pin 17): Analog Ground.
AGND3 (Pin 18): Analog Ground. This is the substrate
connection.
AV
DD
(Pin 19): 5V Analog Supply. Bypass to analog ground
with a 0.1µF ceramic and a 10µF tantalum capacitor.
DV
DD
(Pin 20): 5V Digital Supply. Bypass to digital ground
with a 0.1µF ceramic and a 10µF tantalum capacitor.
OV
DD
(Pin 21): Positive Supply for the Digital Output
Buffers (3V to 5V). Bypass to digital ground with a 0.1µF
ceramic and a 10µF tantalum capacitor.
BUSY (Pin 22): Output shows converter status. It is low
when a conversion is in progress.
SDO (Pin 23): Serial Data Output.
PIN FUNCTIONS
RIPPLE FREQUENCY (Hz)
–60
POWER SUPPLY FEEDTHROUGH (dB)
–40
–20
100 10k 100k 1M
1859 G10
–80
1k
–30
–50
–70
f
SAMPLE
= 100kHz
V
RIPPLE
= 60mV
SUPPLY VOLTAGE (V)
4.5
SUPPLY CURRENT (mA)
8.0
8.5
5.5
1859 G11
7.5
7.0
4.75
5
5.25
f
SAMPLE
= 100kHz
TEMPERATURE (°C)
–50
7.0
POSITIVE SUPPLY CURRENT (mA)
7.5
8.0
8.5
–25 0 25 50
1859 G12
75 100
f
SAMPLE
= 100kHz
