LTC2451
7
2451fg
PIN FUNCTIONS
GND(Pin1,5):Ground.Connecttoagroundplanethrough
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 VCC 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
(VREF = REF+ to REF–) sets the full-scale range.
VCC (Pin 4): Positive Supply Voltage. Bypass to GND
(Pin 1) with a 10F capacitor in parallel with a low series
inductance 0.1F capacitor located as close to the part
as possible.
IN (Pin 6): Analog Input. IN’s single-ended input range
is VREF– to VREF+.
SCL (Pin 7): Serial Clock Input of the I2C 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 I2C 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 VCC).
Exposed Pad (Pin 9): Ground. Must be soldered to PCB
ground.
BLOCK DIAGRAM
16-BIT ∑
A/D CONVERTER
SCL
REF+
VCC
REF–
IN
SDA
2451 BD
I2C
INTERFACE
INTERNAL
OSCILLATOR
3
4
7
8
GND
1, 5, 9
1
2
6