LTC2351-14 Linear Technology, LTC2351-14 Datasheet - Page 8

• Manufacturer Part Number: LTC2351-14
• Description: 1.5Msps Simultaneous Sampling ADC
• Manufacturer: Linear Technology

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PI FU CTIO S
LTC2351-14
8
V
3V to the analog section. Bypass to the solid analog
ground plane with a 10µF ceramic capacitor (or 10µF
tantalum) in parallel with 0.1µF ceramic. Care should be
taken to place the 0.1µF bypass capacitor as close to
Pin 24 as possible. Pin 24 must be tied to Pin 25.
V
3V to the logic section. Bypass to DGND pin and solid
analog ground plane with a 10µF ceramic capacitor (or
10µF tantalum in parallel with 0.1µF ceramic). Keep in
mind that internal digital output signal currents flow
through this pin. Care should be taken to place the 0.1µF
bypass capacitor as close to Pin 25 as possible. Pin 25
must be tied to Pin 24.
SEL2 (Pin 26): Most significant bit controlling the
number of channels being converted. In combination with
SEL1 and SEL0, 000 selects just the first channel (CH0) for
conversion. Incrementing SELx selects additional
channels(CH0–CH5) for conversion. 101, 110 or 111
select all 6 channels for conversion. Must be kept in a fixed
state during conversion and during the subsequent con-
version to read data.
SEL1 (Pin 27): Middle significance bit controlling the
number of channels being converted. In combination with
SEL0 and SEL2, 000 selects just the first channel (CH0) for
conversion. Incrementing SELx selects additional
channels for conversion. 101, 110 or 111 select all 6
channels (CH0–CH5) for conversion. Must be kept in a
fixed state during conversion and during the subsequent
conversion to read data.
SEL0 (Pin 28): Least significant bit controlling the
number of channels being converted. In combination with
SEL1 and SEL2, 000 selects just the first channel (CH0) for
CC
DD
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(Pin 24): 3V Positive Analog Supply. This pin supplies
(Pin 25): 3V Positive Digital Supply. This pin supplies
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conversion. Incrementing SELx selects additional
channels for conversion. 101, 110 or 111 select all 6
channels (CH0–CH5) for conversion. Must be kept in a
fixed state during conversion and during the subsequent
conversion to read data.
BIP (Pin 29): Bipolar/Unipolar Mode. The input differen-
tial range is 0V – 2.5V when BIP is LOW, and it is ±1.25V
when BIP is HIGH. Must be kept in fixed state during
conversion and during subsequent conversion to read
data. When changing BIP between conversions the full
acquisition time must be allowed before starting the next
conversion. The output data is in 2’s complement
format for bipolar mode and straight binary format for
unipolar mode.
CONV (Pin 30): Convert Start. Holds the six analog input
signals and starts the conversion on the rising edge. Two
CONV pulses with SCK in fixed high or fixed low state
starts Nap mode. Four or more CONV pulses with SCK in
fixed high or fixed low state starts Sleep mode.
DGND (Pin 31): Digital Ground. This ground pin must be
tied directly to the solid ground plane. Digital input signal
currents flow through this pin.
SCK (Pin 32): External Clock Input. Advances the conver-
sion process and sequences the output data at SD0 (Pin1)
on the rising edge. One or more SCK pulses wake from
sleep or nap power saving modes. 16 clock cycles are
needed for each of the channels that are activated by SELx
(Pins 26, 27, 28), up to a total of 96 clock cycles needed
to convert and read out all 6 channels.
EXPOSED PAD (Pin 33): GND. Must be tied directly to the
solid ground plane.
235114f