CAT5133 Datasheet, PDF (3/9 Pages) Catalyst Semiconductor – 16 Volt Digitally Programmable Potentiometer (DPP TM) with 128 Taps and an Increment Decrement Interface

CAT5133
Table 2. OPERATION MODES
INC
CS
U/D
High to Low
Low
High
High to Low
Low
Low
High
Low to High
X
Low
Low to High
X
X
High
X
Operation
Wiper toward H
Wiper toward L
Store Wiper
Position
No Store, Return
to Standby
Standby
R_H
C_H
R_W
R_W
C_W
C_L
R_L
Figure 2. Potentiometer Equivalent Circuit
Power-On and Potentiometer Characteristics
The CAT5133 is a 128-position, digital controlled
potentiometer. When applying power to the CAT5133, V_CC
must be supplied prior to or simultaneously with V+. At the
same time, the signals on R_H, R_W and R_L terminals should
not exceed V+. If V+ is applied before V_CC, the electronic
switches of the digital potentiometer are powered in the
absence of the switch control signals, that could result in
multiple switches being turned on. This causes unexpected
wiper settings and possible current overload of the
potentiometer.
When V_CC is applied, the device turns on at the mid-point
wiper location (64) until the wiper register can be loaded
with the nonvolatile memory location previously stored in
the device. After the nonvolatile memory data is loaded into
the wiper register the wiper location will change to the
previously stored wiper position.
At power-down, it is recommended to turn-off first the
signals on R_H, R_W and R_L, followed by V+ and, after that,
V_CC, in order to avoid unexpected transitions of the wiper
and uncontrolled current overload of the potentiometer.
The end-to-end nominal resistance of the potentiometer
has 128 contact points linearly distributed across the total
resistor. Each of these contact points is addressed by the 7 bit
wiper register which is decoded to select one of these 128
contact points.
Each contact point generates a linear resistive value
between the 0 position and the 127 position. These values
can be determined by dividing the end-to-end value of the
potentiometer by 127. The 10 kW potentiometer has a
resistance of ~79 W between each wiper position. However
in addition to the ~79 W for each resistive segment of the
potentiometer, a wiper resistance offset must be considered.
Table 3 shows the effect of this value and how it would
appear on the wiper terminal.
This offset will appear in each of the CAT5133 end-to-end
resistance values in the same way as the 10 kW example.
However resistance between each wiper position for the
50 kW version will be ~395 W and for the 100 kW version
will be ~790 W.
Table 3. POTENTIOMETER RESISTANCE AND WIPER RESISTANCE OFFSET EFFECTS
Position
Typical R_W to R_L Resistance for 10 kW
Digital Potentiometer
Position
Typical R_W to R_H Resistance for 10 kW
Digital Potentiometer
0
70 W or
0 W + 70 W
00
10,070 W or
10,000 W + 70 W
01
149 W or
79 W + 70 W
64
5,047 W or
4,977 W + 70 W
63
5,047 W or
4,977 W + 70 W
126
149 W or
79 W + 70 W
127
10,070 W or
10,000 W + 70 W
127
70 W or
0 W + 70 W
Table 4. ABSOLUTE MAXIMUM RATINGS
Parameters
Ratings
Units
Temperature Under Bias
−55 to +125
C
Storage Temperature
−65 to +150
C
Voltage on any U/D, INC, & CS Pins with Respect to V_CC (Note 5)
Voltage on R_H, R_L, & R_W Pins with Respect to V_CC
V_CC with Respect to Ground
V+ with respect to Ground
−0.3 to +V_CC + 0.3
V
V+
V
−0.3 to +6.0
V
−0.3 to +16.5
V
Wiper Current
6
mA
Lead Soldering temperature (10 seconds)
+300
C
Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the
Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect
device reliability.
5. Latch-up protection is provided for stresses up to 100 mA on the digital from −0.3 V to V_CC + 0.3 V.
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