DS1844 Dallas Semiconductor, DS1844 Datasheet
DS1844
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DS1844 Summary of contents
Page 1
... Operating Temperature Range - Industrial: -40°C to +85°C DESCRIPTION The DS1844 Quad Digital Potentiometer is a four-channel, digitally controlled linear potentiometer. Each potentiometer is comprised of 63 equi-resistive sections and has three terminals accessible to the user. These include the high side terminals, H wiper position on the resistor ladder is selected via an 8-bit register value. Communication and control of the device are supported by two types of serial interface ...
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... The DS1844 is a volatile device and will always power-up with the wiper positions set to mid-tap (position 32-decimal). The end-terminal H will have wiper position value 0-decimal. Because the DS1844 is a 64-position device only 6 bits of data are necessary to write a wiper’s value. However, communication with the DS1844 will require using a full 8 bits, with the remaining 2 bits specifying the potentiometer selected ...
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... The bus must be controlled by a master device which generates the serial clock (SCL), controls the bus access, and generates the START and STOP conditions. The DS1844 operates as a slave on the two-wire bus. Connections to the bus are made via the open-drain I/O lines SDA and SCL. ...
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... Slave transmitter mode: The 1 However, in this mode the direction bit will indicate that the transfer direction is reversed. Serial data is transmitted on SDA by the DS1844 while the serial clock is input on SCL. START and STOP conditions are recognized as the beginning and end of a serial transfer. ...
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... SLAVE ADDRESS A command/control byte is the 1 The command/control byte consists of a 4-bit control code. For the DS1844, this is set as 0101 binary for www.DataSheet4U.com read/write operations. The next 3 bits of the command/ control byte are the device select bits or slave address (A2, A1, A0). They are used by the master device to select which of eight devices accessed ...
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... As in the case of the 5-wire serial protocol, a data byte for the DS1844 will contain potentiometer select data and wiper position value. The six least significant bits of data specify the wiper position value while the two most significant bits specify the potentiometer to be loaded. When the DS1844 has received the data byte, it will respond with an ACKNOWLEDGE ...
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... I -1 (-40°C to +85°C) TYP MAX UNITS +5 +0.5 =2.7V to 5.5V) CC TYP MAX UNITS NOTES 2 µA 250 500 Ohms + 0.3V CC +10 µ µ 0 DS1844 NOTES 1 1,12 19 1,2 1 23,24 23,24 ...
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... LSB +0.25 LSB kHz 750 ppm/°C =2.7V to 5.5V) CC TYP MAX UNITS NOTES ns 0 400 kHz 0 100 µs µs µs µs 0 0.9 µ 300 ns B 1000 300 ns B 300 µs 400 pF DS1844 20,22 *,8 **,22 *,8 **,22 *,5,8 **,22 *,8 **,22 *,8 **,22 *,6,7, **,22 *,8 **,22 *,9 **,22 *,9 **,22 *, **,22 9 ...
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... HLT 125 t RLT t CR equal 3.0V and 5.0V and control port logic pins are driven to the 1000+250=1250 ns before the SCL line RMAX SU:DAT DS1844 =2.7V to 5.5V) CC MAX UNITS NOTES ns 14 14, 15 MHz ...
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... For 5-wire control logic and V = +0.6V. 16. Absolute linearity is used to measure expected wiper voltage versus measured wiper voltage as determined by wiper position. The DS1844 is specified to provide an absolute linearity of ± 0.5 LSB. 17. Relative linearity is used to determine the change in wiper voltage between two adjacent wiper positions. The DS1844 is specified to provide a relative linearity of ± 0.25 dB. ...
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... DS1844 BLOCK DIAGRAM Figure 1 www.DataSheet4U.com WIPER REGISTER CONFIGURATION Figure DS1844 ...
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... SERIAL TIMING DIAGRAM Figure 3 (A), (B) www.DataSheet4U.com (A) WRITING DATA TO THE DS1844 DS1844 ...
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... DATA TRANSFER OVERVIEW Figure 4 www.DataSheet4U.com START COMMAND/CONTROL BYTE Figure 5 2-WIRE READ PROTOCOL Figure 6 2-WIRE WRITE PROTOCOLS Figure DS1844 ...
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... TIMING DIAGRAM Figure 8 www.DataSheet4U.com DIGITAL OUTPUT LOAD Figure DS1844 ...