Dallas Semiconductor DS1869S-100-T-R, DS1869S-100, DS1869S-050-T-R, DS1869S-050, DS1869S-010-T-R Datasheet
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FEATURES
Replaces mechanical variable resistors
Operates from 3V or 5V supplies
Electronic interface provided for digital as
well as manual control
Internal pull-ups with debounce for easy
interfacing to mechanical push buttons
Wiper position is maintained in the absence of
power
Low cost alternative to mechanical controls
Applications include volume, tone, contrast,
brightness, and dimmer control
8-pin SOIC and 8-pin DIP packages are
available
Standard resistance values for Dallastat
- DS1869-10 ~ 10 kΩ
- DS1869-50 ~ 50 kΩ
- DS1869-100 ~ 100 kΩ
Operating temperature range:
- Industrial: -40°C to +85°C
3V to 8V differential supply operational range
PIN ASSIGNMENT
PIN DESCRIPTION
RH - High Terminal of Potentiometer
RW - Wiper Terminal of Potentiometer
RL - Low Terminal of Potentiometer
-V, +V - Voltage Supply Inputs
UC - Up Contact Input
D - Digital Input
DC - Down Contact Input
DESCRIPTION
The DS1869 DallastatTM is a digital rheostat or potentiometer. This device provides 64 possible uniform
tap points over the entire resistive range. The standa rd resistive ranges are 10 kΩ, 50 kΩ, and 100 kΩ.
The Dallastat can be controlled by either a switch contact closure input or a digital source input such as a
CPU. The DS1869 operates from 3V or 5V supplies. Wiper position is maintained in the absence of
power through the use of a EEPROM memory cell array. The EEPROM cell array will withstand more
than 50,000 writes.
The DS1869 is offered in two standard IC packages which include an 8-pin 300-mil DIP and an 8-pin
208-mil SOIC. The DS1869 can be configured to operate using a single pushbutton, dual pushbutton or
digital source input by varying power-on conditions. This is illustrated in Figures 1 and 2. The DS1869
pinouts allow access to both ends of the potentiometer RL, RH, and the wiper, RW. Control inputs include
the digital source input, D, the up contact input, UC, and the down contact input, DC. Other pins include
the positive, +V, and negative, -V, supply inputs. The DS1869 is specified to operate from -40°C to
+85°C.
DS1869
3V Dallastat
TM
Electronic
Digital Rheostat
www.dalsemi.com
8-Pin DIP (300-mil)
See Mech. Drawings Section
(R)
UC
D
(R)
+V
DC
(R
)
V-
1
2
3
4
8
7
6
5
8-Pin SOIC (208-mil)
See Mech. Drawin
g
s Section
(R)
UC
D
(R)
+V
DC
(R
)
V-
1
2
3
4
8
7
6
5
DS1869
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OPERATION
The DS1869 can be configured to operate from a single contact closure, dual contact closure, or a digital
source input. Figures 1 and 2 illustrate both contact closure configurations. Contact closure is defined as a
transition from a high level to a low level on the up contact (UC) or down contact (DC) inputs. All three
control inputs are active when in a low state and are inactive when in a high state.
The DS1869 interprets input pulse widths as the means of controlling wiper movement. A single pulse
input on the UC, DC, or D input terminals will cause the wiper position to move 1/64th of the total
resistance. A transition from a high to low on these inputs is considered the beginning of pulse activity or
contact closure. A single pulse must be greater than 1 ms but lasting no longer than 1 second. Pulse
timings are shown in Figure 5.
Repetitive pulsed inputs can be used to step through each resistive position of the device in a relatively
fast manner (see Figure 5b). The requirement for repetitive pulsed inputs is that pulses must be separated
by a minimum time of 1 ms. If the input is not allowed to be inactive (high) for at least 1 ms, the DS1869
will interpret repetitive pulses as a single pulse.
Pulse inputs lasting longer than 1 second will cause the wiper to move one position every 100 ms
following the initial 1-second hold time. The total time to transcend the entire potentiometer using a
continuous input pulse is given by the formula below:
≈1 second + 63 X 100 ms = 7.3 (seconds)
Single contact closure operation allows the user to control wiper movement in either direction from a
single pushbutton input. Figure 1 presents a typical single pushbutton configuration. The UC input is used
to increment and decrement wiper position for single pushbutton mode of operation. The DC input
provides no functionality in this mode but must be connected to the positive supply voltage (VCC). The
digital source input (D) can be allowed to float.
On device power-up, the configuration shown in Figure 1 must exist in order to enter the single contact
closure mode of operationespecially and specifically, the (DC) input’s direct connection to the positive
supply voltage (VCC).
The initial direction of wiper movement in single pushbutton operation is determined by prior activity.
The initial direction of wiper movement will be opposite to that of the previous activity. Changing the
direction of wiper movement in single pushbutton mode is accomplished by allowing a period of
inactivity on the UC input of (greater than) 1 second, or by moving the wiper to the end of the
potentiometer range. This will occur regardless of whether the input is a continuous pulse, a sequence of
repetitive pulses or a single pulse.
The digital source input, D, was designed for microprocessor or controlled applications. This control
input manipulates the device in the same manner as the single pushbutton configuration, controlling
movement of the wiper position in both upward and downward directions. One added fe ature over the
single pushbutton configuration is the ability to increment or decrement wiper position at a faster rate.
Digital source input control is available regardless of the type of pushbutton configuration.
Dual pushbutton mode of operation is entered when the DC input is floated on power-up. If interf acing
contact closure control inputs to digital logic, the DC input must be interfaced to an open drain drive
which is high impedance during power-up; see Figure 2B. This will prevent the device from entering a
single pushbutton mode of operation.
DS1869
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In dual pushbutton mode, each direction is controlled by the up contact (UC) and down contact (DC)
inputs, respectively. No wait states are required to change wiper direction in dual pushbutton mode. In
dual pushbutton mode, as the wiper position reaches the end of the potentiometer, the direction of wiper
movement will not change. Wiper position will remain at the potentiometers’ end until an opposite
direction input is given.
All contact closure control inputs, UC, DC, and D, are internally pulled-up by a 100 kΩ=resistance. The
UC and DC inputs are internally debounced and require no external components for input signal
conditioning.
DS1869 SINGLE PUSHBUTTON CONFIGURATION
(TYPICAL EXAMPLE) Figure 1
DS1869 DUAL PUSHBUTTON CONFIGURATION
(TYPICAL EXAMPLE) Figure 2A
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