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FEATURES
§ Two linear taper potentiometers
- DS1845-010 one 10k, 100 position &
one 10k, 256 position
- DS1845-050 one 10k, 100 position &
one 50k, 256 postition
- DS1845-100 one 10k, 100 position &
one 100k, 256 position
§ 256 bytes of EEPROM memory
§ Access to data and potentiometer control via
an I
2
C compatible 2-wire interface
§ External Write Enable pin to protect data and
potentiometer settings
§ Nonvolatile wiper storage
§ Operates from 3V or 5V supplies
§ Packaging: Flip Chip Package, 16-ball
CSBGA, 14-pin TSSOP
§ Industrial operating temperature: -40ºC to
+85ºC
16-Ball CSBGA (4mm x 4mm)
14-Pin Flip Chip (100-mil x 100-mil) (Not Shown)
DESCRIPTION
The DS1845 Dual NV Potentiometer and Memory consists of one 100-position linear taper
potentiometer, one 256-position linear taper potentiometer, 256 bytes of EEPROM memory, and a 2-wire
interface. The device provides an ideal method for setting bias voltages and currents in control
applications using a minimum of circuitry. The EEPROM memory allows a user to store configuration
or calibration data for a specific system or device as well as provide control of the potentiometer wiper
settings. Any type of user information may reside in the first 248 bytes of this memory. The next two
addresses of EEPROM memory are for potentiometer settings. Access to this EEPROM is via an
industry standard 2-wire bus. The wiper position of the DS1845, as well as EEPROM data, can be
hardware write-protected using the Write Protect (WP) input pin. Up to eight DS1845s can be installed
on a single 2-wire bus. Access to an individual device is achieved by using a device address that is
determined by the logic levels of address pins A0 though A2. Additionally, the DS1845 will operate
from 3 volt or 5 volt supplies. Three package options are available: Flip Chip Package, 16-ball CSBGA
and 14-pin TSSOP.
DS1845
Dual NV Potentiomete
r
and Memory
www.maxim-ic.com
SDA 1 14 Vcc
SCL 2 13 H0
A0 3 12 W1
A1 4 11 H1
A2 5 10 L1
WP 6 9 W0
GND 7 8 L0
14-Pin TSSOP (173 mil)
A
B
C
D
1 2 3 4
Top View
DS1845
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PIN DESCRIPTIONS
Name TSSOP BGA Description
V
CC
14 A3 Power Supply Terminal. The DS1845 will support supply
voltages ranging from +2.7V to +5.5V.
GND 7 D1 Ground Terminal.
SDA 1 B2 2-Wire serial data interface. The serial data pin is for serial data
transfer to and from the DS1845. The pin is open drain and may
be wire-ORed with other open drain or open collector interfaces.
SCL 2 A2 2-Wire Serial Clock Input. The serial clock input is used to
clock data into the DS1845 on rising edges and clock data out on
falling edges.
WP 6 C1 Write Protect Input. If set to logic 0, the data in memory and the
potentiometer wiper setting may be changed. If set to logic 1, both
the memory and the potentiometer wiper settings will be write
protected. The WP pin is pulled high internally.
A0 3 A1 Address Input. Pins A0, A1, and A2 are used to specify the
address of each DS1845 when used in a multi-dropped
configuration. Up to eight DS1845s may be addressed on a single
2-wire bus.
A1 4 B1 Address Input.
A2 5 C2 Address Input.
H0 13 A4 High terminal of Potentiometer 0. For both potentiometers, it is
not required that the high terminal be connected to a potential
greater than the low terminal. Voltage applied to the high terminal
of each potentiometer cannot exceed V
CC
or go below ground.
H1 11 B3 High terminal of Potentiometer 1.
L0 8 D3 Low terminal of Potentiometer 0. For both potentiometers, it is
not required that the low terminal be connected to a potential less
than the high terminal. Voltage applied to the low terminal of each
potentiometer cannot exceed V
CC
or go below ground.
L1 10 C4 Low terminal of Potentiometer 1.
W0 9 D4 Wiper terminal of Pot 0. The wiper position of Potentiometer 0
is determined by the byte at EEPROM memory location F9h.
Voltage applied to the wiper terminal of each potentiometer cannot
exceed the power supply voltage, V
CC
, or go below ground.
W1 12 B4 Wiper terminal of Pot 1. The wiper position of Potentiometer 1
is determined by the byte at EEPROM memory location F8h.
NC C3 No Connect.
NC D2 No Connect.
DS1845
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DS1845 BLOCK DIAGRAM Figure 1
MEMORY ORGANIZATION
The DS1845’s serial EEPROM is internally organized with 256 words of 1 byte each. Each word requires
an 8-bit address for random word addressing. The byte at address F9h determines the wiper setting for
potentiometer 0, which contains 100 positions. Writing values above 63h to this address sets the wiper to
its uppermost position. The byte at address F8h determines the wiper setting for potentiometer 1, which
contains 256 positions (00h to FFh). The factory default wiper position for both potentiometers is FFh.
Memory locations 00h to F7h are factory programmed to 00h. Address locations FAh though FFh are
reserved and should not be written.
DEVICE OPERATION
Clock and Data Transitions: The SDA pin is normally pulled high with an external resistor or device.
Data on the SDA pin may only change during SCL low time periods. Data changes during SCL high
periods will indicate a start or stop conditions depending on the conditions discussed below. Refer to the
timing diagram Fig 2 for further details.
Start Condition: A high-to-low transition of SDA with SCL high is a start condition which must
precede any other command. Refer to the timing diagram Fig 2 for further details.
Stop Condition: A low-to-high transition of SDA with SCL high is a stop condition. After a read
sequence, the stop command places the DS1845 into a low-power mode. Refer to the timing diagram Fig
2 for further details.
Acknowledge: All address and data byte are transmitted via a serial protocol. The DS1845 pulls the
SDA line low during the ninth clock pulse to acknowledge that it has received each word.
Standby Mode: The DS1845 features a low-power mode that is automatically enabled after power-on,
after a stop command, and after the completion of all internal operations.
VCC
GND
SDA
SCL
WP
A0
A1
A2
H0
W0
L0
H1
W1
L1
248 BYTES
EEPROM
MEMORY
6 RESERVED
BYTES
1 BYTE WIPER
SETTING
POT 0
1 BYTE WIPER
SETTING
POT 1
CONTROL
DATA
POTENTIOMETER 0
2-WIRE
INTERFACE
POTENTIOMETER 1
100
Position
Pot
256
Position
Pot

DS1845B-050

Mfr. #:
Manufacturer:
Maxim Integrated
Description:
Digital Potentiometer ICs Dual NV Potentiometer and Memory
Lifecycle:
New from this manufacturer.
Delivery:
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