Datasheet

LTC2487
10
2487fd
FREQUENCY AT V
CC
(Hz)
1
0
–20
–40
–60
–80
–100
–120
–140
1k 100k
2487 G36
10 100
10k 1M
REJECTION (dB)
V
CC
= 4.1V DC ±0.7V
REF
+
= 2.5V
REF
–
= GND
IN
+
= GND
IN
–
= GND
f
O
= GND
T
A
= 25°C
FREQUENCY AT V
CC
(Hz)
0
–140
RREJECTION (dB)
–120
–80
–60
–40
0
20
100
140
2487 G37
–100
–20
80
180
220200
40
60
120 160
V
CC
= 4.1V DC ±1.4V
REF
+
= 2.5V
REF
–
= GND
IN
+
= GND
IN
–
= GND
f
O
= GND
T
A
= 25°C
FREQUENCY AT V
CC
(Hz)
30600
–60
–40
0
30750
2487 G38
–80
–100
30650 30700 30800
–120
–140
–20
REJECTION (dB)
V
CC
= 4.1V DC ±0.7V
REF
+
= 2.5V
REF
–
= GND
IN
+
= GND
IN
–
= GND
f
O
= GND
T
A
= 25°C
f
O
(Pin 1): Frequency Control Pin. Digital input that controls
the internal conversion clock rate. When f
O
is connected to
GND, the converter uses its internal oscillator running at
307.2kHz. The conversion clock may also be overridden by
driving the f
O
pin with an external clock in order to change
the output rate and the digital fi lter rejection null.
CA0, CA1 (Pins 2, 3): Chip Address Control Pins. These
pins are confi gured as a three-state (LOW, HIGH, Floating)
address control bits for the device’s I
2
C address.
SCL (Pin 4): Serial Clock Pin of the I
2
C Interface. The
LTC2487 can only act as a slave and the SCL pin only ac-
cepts an external serial clock. Data is shifted into the SDA
pin on the rising edges of the SCL clock and output through
the SDA pin on the falling edges of the SCL clock.
SDA (Pin 5): Bidirectional Serial Data Line of the I
2
C Inter-
face. In the transmitter mode (Read), the conversion result
is output through the SDA pin, while in the receiver mode
(Write), the device channel select and confi guration bits
are input through the SDA pin. The pin is high impedance
during the data input mode and is an open drain output
(requires an appropriate pull-up device to V
CC
) during the
data output mode.
GND (Pin 6): Ground. Connect this pin to a common ground
plane through a low impedance connection.
COM (Pin 7): The Common Negative Input (IN
–
) for All
Single-Ended Multiplexer Confi gurations. The voltage
on CH0-CH3 and COM pins can have any value between
TYPICAL PERFORMANCE CHARACTERISTICS
PSRR vs Frequency at V
CC
(2x Speed Mode)
PSRR vs Frequency at V
CC
(2x Speed Mode)
PIN FUNCTIONS
PSRR vs Frequency at V
CC
(2x Speed Mode)