Datasheet

9
LTC2401/LTC2402
PIN FUNCTIONS
UU
U
SCK (Pin 9): Bidirectional Digital Clock Pin. In the Internal
Serial Clock Operation mode, SCK is used as digital output
for the internal serial interface clock during the data output
period. In the External Serial Clock Operation mode, SCK
is used as digital input for the external serial interface. An
internal pull-up current source is automatically activated
in Internal Serial Clock Operation mode. The Serial Clock
mode is determined by the level applied to SCK at power
up and the falling edge of CS.
F
O
(Pin 10): Frequency Control Pin. Digital input that
controls the ADC’s notch frequencies and conversion
time. When the F
O
pin is connected to V
CC
(F
O
= V
CC
), the
converter uses its internal oscillator and the digital filter’s
first null is located at 50Hz. When the F
O
pin is connected
to GND (F
O
= 0V), the converter uses its internal oscillator
and the digital filter’s first null is located at 60Hz. When F
O
is driven by an external clock signal with a frequency f
EOSC
,
the converter uses this signal as its clock and the digital
filter first null is located at a frequency f
EOSC
/2560.
FUNCTIONAL BLOCK DIAGRA
UU
W
TEST CIRCUITS
3.4k
SDO
24012 TC01
Hi-Z TO V
OH
V
OL
TO V
OH
V
OH
TO Hi-Z
C
LOAD
= 20pF
3.4k
SDO
24012 TC02
Hi-Z TO V
OL
V
OH
TO V
OL
V
OL
TO Hi-Z
C
LOAD
= 20pF
V
CC
AUTOCALIBRATION
AND CONTROL
DAC
DECIMATING FIR
INTERNAL
OSCILLATOR
SERIAL
INTERFACE
ADC
∑
∫∫∫
GND
V
CC
V
IN
SDO
SCK
V
REF
CS
F
O
(INT/EXT)
24012 FD