ADS8484 Datasheet, PDF (8/32 Pages) Texas Instruments – 18-BIT, 1.25-MSPS, PSEUDO-BIPOLAR, FULLY DIFFERENTIAL INPUT, MICROPOWER SAMPLING ANALOG-TO-DIGITAL CONVERTER WITH PARALLEL INTERFACE,REFERENCE

ADS8484
SLAS511 – NOVEMBER 2007
PIN ASSIGNMENTS
RGZ PACKAGE
(TOP VIEW)
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+VBD
BUS18/16
BYTE
CONVST
RD
CS
+VA
AGND
AGND
+VA
REFM
REFM
48 47 46 45 44 43 42 41 40 39 38 37
1
36
2
35
3
34
4
33
5
32
6
31
7
30
8
29
9
28
10
27
11
26
12
25
13 14 15 16 17 18 19 20 21 22 23 24
+VBD
DB10
DB11
DB12
DB13
DB14
DB15
DB16
DB17
AGND
AGND
+VA
NC − No internal connection
NOTE: The package thermal pad must be soldered to the printed circuit board for thermal and mechanical performance.
TERMINAL FUNCTIONS
NAME
NO
I/O
DESCRIPTION
AGND
8, 9, 17, 20,
23, 24, 26, – Analog ground
27
BDGND
37
– Digital ground for bus interface digital supply
BUSY
48
O Status output. High when a conversion is in progress.
BUS18/16
2
Bus size select input. Used for selecting 18-bit or 16-bit wide bus transfer.
0: Data bits output on the 18-bit data bus pins DB[17:0].
I 1: Last two data bits D[1:0] from 18-bit wide bus output on:
a) the low byte pins DB[9:2] if BYTE = 0
b) the high byte pins DB[17:10] if BYTE = 1
BYTE
Byte select input. Used for 8-bit bus reading.
3
I 0: No fold back
1: Low byte D[9:2] of the 16 most significant bits is folded back to high byte of the 16 most significant pins DB[17:10].
CONVST
4
I Convert start. The falling edge of this input ends the acquisition period and starts the hold period.
CS
6
I Chip select. The falling edge of this input starts the acquisition period.
Data Bus
DB17
28
DB16
29
DB15
30
DB14
31
DB13
32
DB12
33
DB11
34
DB10
35
BYTE = 0
BUS18/16 = 0
O D17 (MSB)
O D16
O D15
O D14
O D13
O D12
O D11
O D10
8-BIT BUS
BYTE = 1
BUS18/16 = 0
D9
D8
D7
D6
D5
D4
D3
D2
BYTE = 1
BUS18/16 = 1
All ones
All ones
All ones
All ones
All ones
All ones
D1
D0 (LSB)
16-BIT BUS
BYTE = 0
BYTE = 0
BUS18/16 = 0 BUS18/16 = 1
D17 (MSB)
All ones
D16
All ones
D15
All ones
D14
All ones
D13
All ones
D12
All ones
D11
All ones
D10
All ones
18-BIT BUS
BYTE = 0
BUS18/16 = 0
D17 (MSB)
D16
D15
D14
D13
D12
D11
D10
8
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