Datasheet CAT5113 - 3

CAT5113 Functional Diagram
U/D 5−Bit 31 RH R INC Up/Down H V CS Counter CC 30 RH 29 U/D 5−Bit
Control
Nonvolatile 28 INC
and
Memory 1 of 32 Transfer Resistor R
Memory
W Decoder Gates Array RW CS
Power On
2
Recall
RL Store and Recall 1 GND VCC Control GND Circuitry 0 RL RL RW
Figure 1. General Figure 2. Detailed Figure 3. Electronic Potentiometer Implementation Pin Description Device Operation INC:
Increment Control Input The CAT5113 operates like a digitally controlled potentiometer with R The INC input moves the wiper in the up or down direction H and RL equivalent to the high and low terminals and R determined by the condition of the U/D input. W equivalent to the mechanical potentiometer’s wiper. There are 100 available tap positions
U/D:
Up/Down Control Input including the resistor end points, RH and RL. There are 99 The U/D input controls the direction of the wiper movement. resistor elements connected in series between the RH and RL When in a high state and CS is low, any high−to−low terminals. The wiper terminal is connected to one of the 100 transition on INC will cause the wiper to move one taps and controlled by three inputs, INC, U/D and CS. These increment toward the RH terminal. When in a low state and inputs control a seven−bit up/down counter whose output is CS is low, any high-to-low transition on INC will cause the decoded to select the wiper position. The selected wiper wiper to move one increment towards the RL terminal. position can be stored in nonvolatile memory using the INC
R
and CS inputs.
H:
High End Potentiometer Terminal With CS set LOW the CAT5113 is selected and will RH is the high end terminal of the potentiometer. It is not respond to the U/D and INC inputs. HIGH to LOW required that this terminal be connected to a potential greater transitions on INC will increment or decrement the wiper than the RL terminal. Voltage applied to the RH terminal (depending on the state of the U/D input and seven-bit cannot exceed the supply voltage, VCC or go below ground, counter). The wiper, when at either fixed terminal, acts like GND. its mechanical equivalent and does not move beyond the last
RW:
Wiper Potentiometer Terminal position. The value of the counter is stored in nonvolatile RW is the wiper terminal of the potentiometer. Its position on memory whenever CS transitions HIGH while the INC input the resistor array is controlled by the control inputs, INC, is also HIGH. When the CAT5113 is powered-down, the last U/D and CS. Voltage applied to the RW terminal cannot stored wiper counter position is maintained in the exceed the supply voltage, VCC or go below ground, GND. nonvolatile memory. When power is restored, the contents
R
of the memory are recalled and the counter is set to the value
L:
Low End Potentiometer Terminal stored. RL is the low end terminal of the potentiometer. It is not With INC set low, the CAT5113 may be de-selected and required that this terminal be connected to a potential less powered down without storing the current wiper position in than the RH terminal. Voltage applied to the RL terminal nonvolatile memory. This allows the system to always cannot exceed the supply voltage, VCC or go below ground, power up to a preset value stored in nonvolatile memory. GND. RL and RH are electrically interchangeable.
CS:
Chip Select The chip select input is used to activate the control input of the CAT5113 and is active low. When in a high state, activity on the INC and U/D inputs will not affect or change the position of the wiper.
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