Datasheet

6
LTC1605-1/LTC1605-2
16-BIT CAPACITIVE DAC
COMPREF BUF
2.5V REF
CAP
(2.5V)
C
SAMPLE
C
SAMPLE
•
•
•
D15
D0
BUSY
CONTROL LOGIC
R/C BYTE
INTERNAL
CLOCK
CS
ZEROING SWITCHES
V
DIG
V
ANA
V
IN
REF
AGND1
AGND2
DGND
16
1605-1/2 BD
+
–
SUCCESSIVE APPROXIMATION
REGISTER
OUTPUT LATCHES
4k
4k
6K*
20k
3.75k*
10k
OPEN*
*RESISTOR VALUES FOR THE LTC1605-2
V
IN
(Pin 1): Analog Input. Connect through a 200Ω
resistor to the analog input. Full-scale input range is 0V
to 4V for the LTC1605-1 and ±4V for the LTC1605-2.
AGND1 (Pin 2): Analog Ground. Tie to analog ground
plane.
REF (Pin 3): 2.5V Reference Output. Bypass with 2.2µF
tantalum capacitor. Can be driven with an external refer-
ence.
CAP (Pin 4): Reference Buffer Output. Bypass with 2.2µF
tantalum capacitor.
AGND2 (Pin 5): Analog Ground. Tie to analog ground
plane.
D15 to D8 (Pins 6 to 13): Three-State Data Outputs.
Hi-Z state when CS is high or when R/C is low.
DGND (Pin 14): Digital Ground.
D7 to D0 (Pins 15 to 22): Three-State Data Outputs.
Hi-Z state when CS is high or when R/C is low.
BYTE (Pin 23): Byte Select. With BYTE low, data will be
output with Pin 6 (D15) being the MSB and Pin 22 (D0)
PIN FUNCTIONS
UUU
being the LSB. With BYTE high the upper eight bits and
the lower eight bits will be switched. The MSB is output
on Pin 15 and bit 8 is output on Pin 22. Bit 7 is output on
Pin 6 and the LSB is output on Pin 13.
R/C (Pin 24): Read/Convert Input. With CS low, a falling
edge on R/C puts the internal sample-and-hold into the
hold state and starts a conversion. With CS low, a rising
edge on R/C enables the output data bits.
CS (Pin 25): Chip Select. Internally OR’d with R/C. With
R/C low, a falling edge on CS will initiate a conversion.
With R/C high, a falling edge on CS will enable the output
data.
BUSY (Pin 26): Output Shows Converter Status. It is low
when a conversion is in progress. Data valid on the rising
edge of BUSY. CS or R/C must be high when BUSY rises
or another conversion will start without time for signal
acquisition.
V
ANA
(Pin 27): 5V Analog Supply. Bypass to ground with
a 0.1µF ceramic and a 10µF tantalum capacitor.
V
DIG
(Pin 28): 5V Digital Supply. Connect directly to
Pin␣ 27.
FU CTIO AL BLOCK DIAGRA
UU
W