Datasheet CAT5112 (ON Semiconductor) - 3
| Manufacturer | ON Semiconductor |
| Description | 32‐tap Digital Potentiometer (POT) with Buffered Wiper |
| Pages / Page | 11 / 3 — CAT5112. Figure 1. Functional Diagram. Figure 2. Electronic Potentiometer … |
| File Format / Size | PDF / 230 Kb |
| Document Language | English |
CAT5112. Figure 1. Functional Diagram. Figure 2. Electronic Potentiometer Implementation. Pin Description. Device Operation. INC:
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Text Version of Document
CAT5112
RH VCC RH U/D Control + INC and R + Memory WB – R CS WB – Power On Recall RL GND RL
Figure 1. Functional Diagram Figure 2. Electronic Potentiometer Implementation Pin Description Device Operation INC:
Increment Control Input The CAT5112 operates like a digitally controlled potentiometer with R The INC input (on the falling edge) moves the wiper in the H and RL equivalent to the high and low terminals and R up or down direction determined by the condition of the U/D WB equivalent to the mechanical potentiometer’s wiper. There are 32 available tap positions input. including the resistor end points, RH and RL. There are 31
U/D:
Up/Down Control Input resistor elements connected in series between the RH and RL The U/D input controls the direction of the wiper movement. terminals. The wiper terminal is connected to one of the 32 When in a high state and CS is low, any high−to−low taps and controlled by three inputs, INC, U/D and CS. These transition on INC will cause the wiper to move one inputs control a five-bit up/down counter whose output is increment toward the RH terminal. When in a low state and decoded to select the wiper position. The selected wiper CS is low, any high-to-low transition on INC will cause the position can be stored in nonvolatile memory using the INC wiper to move one increment towards the RL terminal. and CS inputs.
R
With CS set LOW the CAT5112 is selected and will
H:
High End Potentiometer Terminal respond to the U/D and INC inputs. HIGH to LOW RH is the high end terminal of the potentiometer. It is not transitions on INC will increment or decrement the wiper required that this terminal be connected to a potential greater (depending on the state of the U/D input and five-bit than the RL terminal. Voltage applied to the RH terminal counter). The wiper, when at either fixed terminal, acts like cannot exceed the supply voltage, VCC or go below ground, its mechanical equivalent and does not move beyond the last GND. position. The value of the counter is stored in nonvolatile
RWB:
Wiper Potentiometer Terminal (Buffered) memory whenever CS transitions HIGH while the INC input RWB is the buffered wiper terminal of the potentiometer. Its is also HIGH. When the CAT5112 is powered-down, the last position on the resistor array is controlled by the control stored wiper counter position is maintained in the inputs, INC, U/D and CS. 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 CAT5112 may be deselected 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 CAT5112 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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RH VCC RH U/D Control + INC and R + Memory WB – R CS WB – Power On Recall RL GND RL
Figure 1. Functional Diagram Figure 2. Electronic Potentiometer Implementation Pin Description Device Operation INC:
Increment Control Input The CAT5112 operates like a digitally controlled potentiometer with R The INC input (on the falling edge) moves the wiper in the H and RL equivalent to the high and low terminals and R up or down direction determined by the condition of the U/D WB equivalent to the mechanical potentiometer’s wiper. There are 32 available tap positions input. including the resistor end points, RH and RL. There are 31
U/D:
Up/Down Control Input resistor elements connected in series between the RH and RL The U/D input controls the direction of the wiper movement. terminals. The wiper terminal is connected to one of the 32 When in a high state and CS is low, any high−to−low taps and controlled by three inputs, INC, U/D and CS. These transition on INC will cause the wiper to move one inputs control a five-bit up/down counter whose output is increment toward the RH terminal. When in a low state and decoded to select the wiper position. The selected wiper CS is low, any high-to-low transition on INC will cause the position can be stored in nonvolatile memory using the INC wiper to move one increment towards the RL terminal. and CS inputs.
R
With CS set LOW the CAT5112 is selected and will
H:
High End Potentiometer Terminal respond to the U/D and INC inputs. HIGH to LOW RH is the high end terminal of the potentiometer. It is not transitions on INC will increment or decrement the wiper required that this terminal be connected to a potential greater (depending on the state of the U/D input and five-bit than the RL terminal. Voltage applied to the RH terminal counter). The wiper, when at either fixed terminal, acts like cannot exceed the supply voltage, VCC or go below ground, its mechanical equivalent and does not move beyond the last GND. position. The value of the counter is stored in nonvolatile
RWB:
Wiper Potentiometer Terminal (Buffered) memory whenever CS transitions HIGH while the INC input RWB is the buffered wiper terminal of the potentiometer. Its is also HIGH. When the CAT5112 is powered-down, the last position on the resistor array is controlled by the control stored wiper counter position is maintained in the inputs, INC, U/D and CS. 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 CAT5112 may be deselected 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 CAT5112 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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