Datasheet

LTC2172-14/
LTC2171-14/LTC2170-14
18
21721014fb
pin FuncTions
PAR/SER (Pin 47): Programming Mode Selection Pin.
Connect to ground to enable serial programming mode.
CS, SCK, SDI and SDO become a serial interface that con-
trols the A/D operating modes. Connect to V
DD
to enable
parallel programming mode where CS, SCK, SDI and SDO
become parallel logic inputs that control a reduced set of
the A/D operating modes. PAR/SER should be connected
directly to ground or the V
DD
of the part and not be driven
by a logic signal.
V
REF
(Pin 48): Reference Voltage Output. Bypass to ground
with a 1µF ceramic capacitor, nominally 1.25V.
SENSE (Pin 50): Reference Programming Pin. Connect-
ing SENSE to V
DD
selects the internal reference and a
±1V input range. Connecting SENSE to ground selects
the internal reference and a ±0.5V input range. An external
reference between 0.625V and 1.3V applied to SENSE
selects an input range of ±0.8 • V
SENSE
.
LVDS OUTPUTS
The following pins are differential LVDS outputs. The
output current level is programmable. There is an op-
tional internal 100Ω termination resistor between the
pins of each LVDS output pair.
OUT4B
–
/OUT4B
+
, OUT4A
–
/OUT4A
+
(Pins 23/24,
Pins 25/ 26): Serial Data Outputs for Channel 4. In 1-lane
output mode, only OUT4A
–
/OUT4A
+
are used.
OUT3B
–
/OUT3B
+
, OUT3A
–
/OUT3A
+
(Pins 27/28,
Pins 29/30): Serial Data Outputs for Channel 3. In
1-lane output mode, only OUT3A
–
/OUT3A
+
are used.
FR
–
/FR
+
(Pin 31/Pin 32): Frame Start Output.
DCO
–
/DCO
+
(Pin 35/Pin 36): Data Clock Output.
OUT2B
–
/OUT2B
+
, OUT2A
–
/OUT2A
+
(Pins 37/38,
Pins 39/40): Serial Data Outputs for Channel 2. In
1-lane output mode, only OUT2A
–
/OUT2A
+
are used.
OUT1B
–
/OUT1B
+
, OUT1A
–
/OUT1A
+
(Pins 41/42,
Pins 43/44): Serial Data Outputs for Channel 1. In
1-lane output mode, only OUT1A
–
/OUT1A
+
are used.