AS1545
Datasheet - Detailed Description
Figure 42. Straight Binary Transfer Function for
Single-Ended, RANGE = 0
Figure 43. Straight Binary Transfer Function for
Single-Ended, RANGE = 1
Full Scale = VREF
Zero Scale = 0
1LSB = VREF/4096
Full Scale = +2VREF
Full Scale
Full Scale
(FS)
Transition
Zero Scale = 0
(FS)
11...111
11...110
11....101
11...111
1LSB = VREF/4096
Transition
11...110
11....101
00...011
00...010
00...001
00...000
00...011
00...010
00...001
00...000
0
1
2
3
FS - 3/2LSB
0
1
2
3
FS - 3/2LSB
Input Voltage VINx (LSB)
Input Voltage VINx - VINy (LSB)
Figure 44. Two’s Complement Transfer Function for
Differential, RANGE = 0
Figure 45. Two’s Complement Transfer Function for
Differential, RANGE = 1
Full Scale = +VREF
Full Scale = VREF/2
Zero Scale = -VREF
1LSB = VREF/4096
Zero Scale = -VREF/2
1LSB = VREF/4096
011....111
011....111
011...110
011...110
000...010
000...001
000...000
111...111
111...110
111...101
000...010
000...001
000...000
111...111
111...110
111...101
100...001
100...000
100...001
100...000
-FS
ZS
+FS - 1LSB
-FS
ZS
+FS - 1LSB
Input Voltage VINx (LSB)
Input Voltage VINx - VINy (LSB)
Digital Inputs
V
Functionality
DRIVE
The AS1545 also has a VDRIVE feature to control the voltage at which the serial interface operates and allows the ADC
to easily interface to both 3V and 5V processors. For example, if the AS1545 was operated with a VDD of 5V, the
VDRIVE pin could be powered from a 3V supply, allowing a large dynamic range with low voltage digital processors.
Therefore, the AS1545 could be used with the 2 × VREF input range, with a VDD of 5V while still being able to interface
to 3V digital parts.
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