Datasheet

LTC2451
7
2451fg
PIN FUNCTIONS
GND (Pin 1, 5): Ground. Connect to a ground plane through
a low impedance connection.
REF
–
(Pin 2), REF
+
(Pin 3): Differential Reference Input.
The voltage on these pins can have any value between
GND and V
CC
as long as the reference positive input, REF
+
,
remains more positive than the negative reference input,
REF
–
, by at least 2.5V. The differential reference voltage
(V
REF
= REF
+
to REF
–
) sets the full-scale range.
V
CC
(Pin 4): Positive Supply Voltage. Bypass to GND
(Pin 1) with a 10µF capacitor in parallel with a low series
inductance 0.1µF capacitor located as close to the part
as possible.
IN (Pin 6): Analog Input. IN’s single-ended input range
is V
REF
–
to V
REF
+
.
SCL (Pin 7): Serial Clock Input of the I
2
C Interface. The
LTC2451 can only act as a slave and the SCL pin only
accepts an external serial clock. Data is shifted into the
SDA pin on the rising edges of SCL and output through
the SDA pin on the falling edges of SCL.
SDA (Pin 8): Bidirectional Serial Data Line of the I
2
C In-
terface. The conversion result is output through the SDA
pin. The pin is high impedance unless the LTC2451 is in
the data output mode. While the LTC2451 is in the data
output mode, SDA is an open-drain pull-down (which
requires an external 1.7k pull-up resistor to V
CC
).
Exposed Pad (Pin 9): Ground. Must be soldered to PCB
ground.
BLOCK DIAGRAM
16-BIT ∆∑
A/D CONVERTER
SCL
REF
+
V
CC
REF
–
IN
SDA
2451 BD
I
2
C
INTERFACE
INTERNAL
OSCILLATOR
3 4
7
8
GND
1, 5, 9
12
6