LTC1282 Datasheet, PDF (9/24 Pages) Linear Technology – 3V 140ksps 12-Bit Sampling A/D Converter with Reference

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PI FU CTIO S
A_IN (Pin 1): Analog Input. 0V to 2.5V (Unipolar), ±1.25V
(Bipolar).
V_REF (Pin 2): +1.20V Reference Output. Bypass to
AGND (10µF tantalum in parallel with 0.1µF ceramic).
AGND (Pin 3): Analog Ground.
D11-D4 (Pins 4 to 11): Three-State Data Outputs. D11
is the Most Significant Bit.
DGND (Pin 12): Digital Ground.
D3/11-D0/8 (Pins 13 to 16): Three-State Data Outputs.
NC (Pins 17 and 18): No Connection.
HBEN (Pin 19): High Byte Enable Input. This pin is used
to multiplex the internal 12-bit conversion result into
the lower bit outputs (D7 and D0/8). See Table 1. HBEN
also disables conversion start when HIGH.
LTC1282
RD (Pin 20): READ Input. This active low signal starts a
conversion when CS and HBEN are low. RD also enables
the output drivers when CS is low.
CS (Pin 21): The CHIP SELECT Input must be low for the
ADC to recognize RD and HBEN inputs.
BUSY (Pin 22): The BUSY Output shows the converter
status. It is low when a conversion is in progress.
V_SS (Pin 23): Bipolar Mode — Negative Supply, – 3V.
Bypass to AGND with 0.1µF ceramic.
Unipolar Mode — Tie to DGND.
V_DD (Pin 24): Positive Supply, 3V. Bypass to AGND (10µF
tantalum in parallel with 0.1µF ceramic).
Table 1. Data Bus Output, CS and RD = LOW
Pin 4 Pin 5 Pin 6 Pin 7
MNEMONIC*
D11
D10
D9
D8
HBEN = LOW
DB11 DB10 DB9 DB8
HBEN = HIGH
DB11 DB10 DB9 DB8
*D11...D0/8 are the ADC data output pins.
DB11...DB0 are the 12-bit conversion results, DB11 is the MSB.
Pin 8
D7
DB7
LOW
Pin 9
D6
DB6
LOW
Pin 10
D5
DB5
LOW
Pin 11
D4
DB4
LOW
Pin 13
D3/11
DB3
DB11
Pin 14
D2/10
DB2
DB10
Pin 15
D1/9
DB1
DB9
Pin 16
D0/8
DB0
DB8
TEST CIRCUITS
Load Circuits for Access Time
5V
3k
DBN
DBN
3k
C_L
C_L
DGND
(A) Hi-Z TO V_OH, (t₃)
AND V_OL TO V_OH, (t₆)
DGND
(B) Hi-Z TO V_OL, (t₃)
AND V_OH TO V_OL, (t₆)
1282 TC01
Load Circuits for Output Float Delay
5V
3k
DBN
DBN
3k
10pF
10pF
DGND
(A) V_OH TO Hi-Z
DGND
(B) V_OL TO Hi-Z
1282 TC02
9