ds1841nt-r Maxim Integrated Products, Inc., ds1841nt-r Datasheet - Page 6

• Manufacturer Part Number: ds1841nt-r
• Description: Ds1841 - New! - Temperature-controlled, Nv, I?c, Logarithmic Resistor
• Manufacturer: Maxim Integrated Products, Inc.

Temperature-Controlled, NV, I
Logarithmic Resistor
The DS1841 operates in one of two modes: LUT Mode
and LUT Adder Mode. In LUT Mode and LUT Adder
Mode, the resistor’s wiper position is controlled as a
function of the temperature measured by the DS1841’s
internal temperature sensor. The difference between
the two LUT modes is the way the resistor’s wiper posi-
tion is calculated. Detailed descriptions of these two
modes, as well as additional features of the DS1841,
are discussed in subsequent sections.
The DS1841’s resistor consists of 128 resistive steps
between RW and RGND with a series resistor, R
between RH and RW. The wiper position and the output
seen on RW are decoded based on the value in the
wiper register (WR). The step size of each position is
optimized to produce a linear response when used in
the feedback network of a DC-DC converter.
6
_______________________________________________________________________________________
PIN
10
—
1
2
3
4
5
6
7
8
9
NAME
RGND
GND
SDA
N.C.
SCL
V
RW
RH
A1
A0
EP
CC
Digital Resistor Description
Detailed Description
Exposed Paddle. Must be connected to ground.
I
Ground
Power Supply
Address Select Inputs. Determines I
Slave Address Byte and Address Pins sections for more details).
Low Terminal of Resistor. Must be connected to GND.
Wiper Terminal
Terminal with Fixed Resistor Added in Series with Digital Resistor
No Connection
I
2
2
C Serial Data. Input/output for I
C Serial Clock. Input for I
2
C clock.
S
,
2
C data.
2
C slave address. Device address is 01010A
The DS1841 mode of operation is determined by the
Update Mode bit (Control Register 1, address 03h, bit 0)
and the Adder Mode bit (Control Register 1, address
03h, bit 1). Table 1 illustrates how the two control bits
are used to select the operating mode. When shipped
from the factory, the DS1841 is programmed with the
Update Mode and Adder Mode bits set to 1, hence con-
figuring the DS1841 in LUT Adder Mode. See Appendix
A for a detailed table of the control logic bit functions.
Table 1. Operating Modes
UPDATE MODE
FUNCTION
BIT
1
1
2
C,
ADDER MODE BIT
0
1
Pin Description
Mode Selection
1
LUT Adder Mode
A
0
X (see the
LUT Mode
(Default)
MODE