ltc1278-5 Linear Technology Corporation, ltc1278-5 Datasheet - Page 7

• Manufacturer Part Number: ltc1278-5
• Description: 12-bit, 500ksps Sampling A/d Converter With Shutdown
• Manufacturer: Linear Technology Corporation

PI FU CTIO S
FU CTIO AL BLOCK DIAGRA
A
(Bipolar).
V
(10 F tantalum in parallel with 0.1 F ceramic).
AGND (Pin 3): Analog Ground.
D11 to D4 (Pins 11 to 4): Three-State Data Outputs.
D11 is the Most Significant Bit.
DGND (Pin 12): Digital Ground.
D3 to D0 (Pins 13 to 16): Three-State Data Outputs.
DV
SHDN (Pin 18): Power Shutdown.
CONVST (Pin 19): Conversion Start Signal. This active
low signal starts a conversion on its falling edge (to
recognize CONVST, CS has to be low).
IN
REF
U
DD
U
(Pin 1): Analog Input. 0V to 5V (Unipolar), 2.5V
(Pin 2): 2.42V Reference Output. Bypass to AGND
(Pin 17 ): Digital Power Supply, 5V. Tie to AV
U
DGND
AGND
V
U
A
REF
IN
U
INTERNAL
2.42V REF
CLOCK
SHDN
12-BIT CAPACITIVE DAC
SUCCESSIVE APPROXIMATION
CONTROL LOGIC
CONVST
REGISTER
C
SAMPLE
12
RD
W
DD
pin.
CS
BUSY
RD (Pin 20): READ Input. This enables the output
drivers when CS is low.
CS (Pin 21): The CHIP SELECT input must be low for the
ADC to recognize CONVST and RD inputs.
BUSY (Pin 22): The BUSY output shows the converter
status. It is low when a conversion is in progress.
V
tion. Bypass to AGND with 0.1 F ceramic. Analog
ground for unipolar operation.
AV
(10 F tantalum in parallel with 0.1 F ceramic).
SS
12
DD
COMPARATOR
(Pin 23): Negative Supply. – 5V for bipolar opera-
ZEROING
SWITCH
(Pin 24): Positive Supply, 5V. Bypass to AGND
OUTPUT LATCHES
LTC1278 • BD
AV
DV
V
(0V FOR UNIPOLAR MODE
OR –5V FOR BIPOLAR MODE)
SS
DD
DD
•
•
•
D11
D0
LTC1278
7