LSI/CSI LS7193S10

LS7190, LS7191, 7192, LS7193, LS7194, and LS7195 are different models of three-terminal digital potentiometers. Quadrature clocks from an incremental encoder, or non-quadrature up/down clocks, are applied to the A and B inputs. These clocks drive an internal 6-bit up/down counter with a count N ranging from 0 to 63, corresponding to 64 tap positions on a resistor ladder composed of 64 equal resistors. Each count equals one incremental resistance change of R/64 between the wiper terminal Tw and either end terminal Ta or Tb. For example, for a 20K resistor, the incremental resistance is 20K/64 = 312.5Ω; for a 50K resistor, 50K/64 = 781Ω; for a 100K resistor, 100K/64 = 1.6K. For a 20K resistor, count N = 1 corresponds to a Tw-to-Tb resistance = (20K/64) × 1 = 312.5Ω, and a Tw-to-Ta resistance = (20K/64) × (64 - 1) = 19.688K. When N = 63, the Tw-to-Tb resistance is (20K/64) × 63 = 19.688K, and the Tw-to-Ta resistance = (20K/64) × (64 - 63) = 312.5Ω.

LS7190 and LS7193 interface with quadrature clocks from incremental encoders; LS7191/92 and LS7194/95 interface with non-quadrature up (A) / down (B) clocks. The A and B inputs of LS7190/91 and LS7193/94 are debounced, allowing these signals to be sourced from mechanical encoders or pushbutton switches. The A and B inputs of LS7192 and LS7195 are not debounced, enabling the use of fast clocks from electronic clock sources. The following summarizes the key functional differences among the models: ● LS7190 and LS7193: A/B inputs in quadrature mode, A/B inputs debounced. ● LS7191 and LS7194: A/B inputs in non-quadrature mode, A/B inputs debounced. ● LS7192 and LS7195: A/B inputs in non-quadrature mode, A/B inputs not debounced.

The RxD, TxD, SCK, and CS/ inputs together form an SPI bus for communication with a host MCU. LS7190, LS7191, and LS7192 feature an SPI bus interface. The MCU can preset the counter in these devices to set a specific tap position, or read their current tap position and save the data to external non-volatile memory.

The counter in all these devices can have its counting function enabled or disabled via the CEN input, or preset to N = 32 via the RST/ input, corresponding to the midpoint position of the potentiometer wiper terminal Tw. At power-up, Tw is set to N = 32.

• 64 position wiper control
• Direct interface with Incremental Encoders Adjustable debounce for mechanical encoder/switch
• Configurable to operate with non-quadrature clock
• SPI interface for host MCU controllers
• Supply voltage: 3 to 5 volts
• Available in 20K, 50K and 100K versions
• Qualifies for automotive temperature range
• Available in SOIC-8, SOIC-14 and TSSOP-14

• Replacement for mechanical potentiometer
• Potentiometer adjustment with mechanical Incremental encoder
• Remote adjustment of instrumentation for gain, offset, time constant, line impedance matching, audio equipment volume control etc.