Datasheet

LTC1604
6
1604fa
TYPICAL PERFORMANCE CHARACTERISTICS
Intermodulaton Distortion
Power Supply Feedthrough vs
Ripple Frequency
Input Common Mode Rejection
vs Input Frequency
FREQUENCY (kHz)
020
AMPLITUDE (dB)
80 100
0
–20
–40
–60
–80
–100
–120
–140
1604 G06
40 60 160120 140
f
SAMPLE
= 333kHz
f
IN1
= 29.3kHz
f
IN2
= 32.4kHz
INPUT FREQUENCY (Hz)
1k
AMPLITUDE OF POWER SUPPLY
FEEDTHROUGH (dB)
0
–20
–40
–60
–80
–100
–120
10k 100k 1M
1604 G07
f
SAMPLE
= 333kHz
V
RIPPLE
= 10mV
V
SS
A
VDD
INPUT FREQUENCY (Hz)
1k
COMMON MODE REJECTION (dB)
80
70
60
50
40
30
20
10
0
10k 100k
1604G09
1M
PIN FUNCTIONS
A
IN
+
(Pin 1): Positive Analog Input. The ADC converts the
difference voltage between A
IN
+
and A
IN
–
with a differ-
ential range of ±2.5V. A
IN
+
has a ±2.5V input range when
A
IN
–
is grounded.
A
IN
–
(Pin 2): Negative Analog Input. Can be grounded, tied
to a DC voltage or driven differentially with A
IN
+
.
V
REF
(Pin 3): 2.5V Reference Output. Bypass to AGND with
2.2μF tantalum in parallel with 0.1μF ceramic.
REFCOMP (Pin 4): 4.375 Reference Compensation Pin.
Bypass to AGND with 47μF tantalum in parallel with 0.1μF
ceramic.
AGND (Pins 5 to 8): Analog Grounds. Tie to analog ground
plane.
DV
DD
(Pin 9): 5V Digital Power Supply. Bypass to DGND
with 10μF tantalum in parallel with 0.1μF ceramic.
DGND (Pin 10): Digital Ground for Internal Logic. Tie to
analog ground plane.
D15 to D0 (Pins 11 to 26): Three-State Data Outputs. D15
is the Most Significant Bit.
BUSY (Pin 27): The BUSY output shows the converter
status. It is low when a conversion is in progress. Data is
valid on the rising edge of BUSY.
OGND (Pin 28): Digital Ground for Output Drivers.
OV
DD
(Pin 29): Digital Power Supply for Output Drivers.
Bypass to OGND with 10μF tantalum in parallel with 0.1μF
ceramic.
RD (Pin 30): Read Input. A logic low enables the output
drivers when CS is low.
CONVST (Pin 31): Conversion Start Signal. This active
low signal starts a conversion on its falling edge when
CS is low.
CS (Pin 32): The Chip Select Input. Must be low for the
ADC to recognize CONVST and RD inputs.
SHDN (Pin 33): Power Shutdown. Drive this pin low with
CS low for nap mode. Drive this pin low with CS high for
sleep mode.
V
SS
(Pin 34): –5V Negative Supply. Bypass to AGND with
10μF tantalum in parallel with 0.1μF ceramic.
AV
DD
(Pin 35): 5V Analog Power Supply. Bypass to AGND
with 10μF tantalum in parallel with 0.1μF ceramic.
AV
DD
(Pin 36): 5V Analog Power Supply. Bypass to AGND
with 10μF tantalum in parallel with 0.1μF ceramic and
connect this pin to Pin 35 with a 10Ω resistor.