Datasheet

AD5547/AD5557 Data Sheet
Rev. D | Page 16 of 20
BIPOLAR MODE
4-Quadrant Multiplying Mode, V
OUT
= –V
REF
to +V
REF
The AD5547/AD5557 contain on-chip all the 4-quadrant
resistors necessary for precision bipolar multiplying operation.
Such a feature minimizes the number of exponent components
to only a voltage reference, dual op amp, and compensation
capacitor (see Figure 23). For example, with a +10 V reference,
the circuit yields a precision, bipolar –10 V to +10 V output.
V
OUT
= (D/32768 − 1) × V
REF
(AD5547) (5)
V
OUT
= (D/16384 − 1) × V
REF
(AD5557) (6)
Table 9 shows some of the results for the 16-bit AD5547.
Table 9. AD5547 Output vs. Code
D in Binary V
OUT
1111 1111 1111 1111 +V
REF
(32,767/32,768)
1000 0000 0000 0001 +V
REF
(1/32,768)
1000 0000 0000 0000 0
0111 1111 1111 1111 –V
REF
(1/32,768)
0000 0000 0000 0000
–V
REF
WR
WR
RS
RS
C6 0.1µF
C7 1µF
2
+10V
–10V
–15V
–10V TO +10V
+15V
04452-006
AD8512
AD8512
AD5547/AD5557
C8
U2A
R
1A
16/14 DATA
VDD
R
COMA
R2
U1
R1
R
OFSA
R
FBA
C9
RFBROFS
MSB A0, A1
I
OUTA
AGNDA
U2B
C4 1µF
C1
1µF
C2
0.1µF
C3
0.1µF
C5 0.1µF
VOUT
V
REFA
MSB
A0, A1
LDAC
LDAC
+V
–V
GND
ADR01
4
V
OUT
TRIM
5
6
V
IN
U3
2
+15V
+5V
16-/14-BIT
DAC A
Figure 23. 4-Quadrant Multiplying Mode, V
OUT
= –V
REF
to +V
REF