CAT525_0711 Datasheet, PDF (9/16 Pages) Catalyst Semiconductor – Quad Digitally Programmable Potentiometer (DPP™) with 256 Taps and Microwire Interface

CAT525
APPLICATION CIRCUITS
CONTROL
& DATA
+5V
V_I
R_I
R_F
V_DD
V_REFH
CAT525
V_DPP
+15V
+
V_OUT
– _{OP 07}
GND
V_REFL
-15V
V _OUT
=
V_DPP
( R_I+ R_F )
R_I
-
V_I R_F
For R _I = R_F
V_OUT = 2V_DPP - V_I
DPP INPUT DPP OUTPUT
ANALOG OUTPUT
V_DPP
=
CODE
255
x
(V_FS -
V_ZERO)
+
V_ZERO
MSB LSB ^VFS ^{= 0.99V}REF
V_REF = 5V
V_ZERO = 0.01V_REF
R_I = R_F
1111 1111
1000 0000
0111 1111
0000 0001
0000 0000
255
255
×
0.98V_REF
+
0.01V_REF
=
0.990V_REF
128
255
×
0.98V_REF
+
0.01V_REF
=
0.502V_REF
127
255
×
0.98V_REF
+
0.01V_REF
=
0.498V_REF
1
255
×
0.98V_REF
+
0.01V_REF
=
0.014V_REF
0
255
×
0.98V_REF
+
0.01V_REF
=
0.010V_REF
V_OUT = +4.90V
V_OUT = +0.02V
V_OUT = -0.02V
V_OUT = -4.86V
V_OUT = -4.90V
Bipolar DPP Output
CONTROL
& DATA
+5V
R_I
R_F
V_DD
V_REFH
CAT525
V_DPP
+15V
–
+
OP 07
V_OUT
GND
V_REFL
-15V
V_OUT = (1 + ^RRFI ) V_DPP
Amplified DPP Output
+5V
V_DD
V_REF
V_REFH
FINE ADJUST
DPP
127R_C
COARSE ADJUST
DPP
GND
V_REFL
+V
R_C
+
V_OFFSET
–
R_C
=
V_REF
256 x 1µA
Fine adjust gives ±1 LSB change in V_OFFSET
when V_OFFSET = V_REF/2
Coarse-Fine Offset Control by Averaging DPP
Outputs for Single Power Supply Systems
+5V
V_DD
+V_REF
V_REFH
FINE ADJUST
DPP
127R_C
COARSE ADJUST
R_C
DPP
(+V_REF) - (V_OFFSET+)
R_C =
1µA
R₀ =
(-V_REF) + (V_OFFSET+)
1µA
GND
V_REFL
R₀
-V_REF
+V
+
V_OFFSET
–
-V
Coarse-Fine Offset Control by Averaging DPP
Outputs for Dual Power Supply Systems
© Catalyst Semiconductor, Inc.
9
Characteristics subject to change without notice
Doc. No. MD-2001 Rev. H