DS1841(2008) 查看數據表（PDF） - Maxim Integrated

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DS1841
(Rev.:2008)

Temperature-Controlled, NV, I2C, Logarithmic Resistor

Maxim Integrated 

Temperature-Controlled, NV, I2C,

Logarithmic Resistor

LUT Adder Mode (Default)

LUT Adder Mode is selected by setting the Update

Mode bit to 1 and the Adder Mode bit to 1. This mode

operates similar to LUT Mode with one major difference

(see the LUT Mode and LUT Adder Mode Block

Diagram). The WR is loaded with the sum of the values

of LUTVAL (the value pointed to by the address stored

in LUTAR) and IVR. Furthermore, in this mode, the val-

ues programmed into the LUT are signed two’s com-

plement. This allows convenient positive or negative

offsetting of the nominal IVR value. WR resistance val-

ues clamp at 00h and 7Fh (the MSB is ignored).

LUT Mode

LUT Mode is selected by setting the Update Mode bit

(Control Register 1, address 03h, bit 0) to a 1 and the

Adder Mode bit (Control Register 1, address 03h, bit 1)

to a 0. An overview of the DS1841 in this mode is illus-

trated in the LUT Mode and LUT Adder Mode Block

Diagram. The memory map for the LUT Mode and the

LUT Adder Mode is shown in Table 2. The major differ-

ence between the two LUT modes is whether the value

in the IVR is added to the values stored in the LUT. The

dashed line/arrow shown in the LUT Drive Mode Block

Diagram is not active in LUT Mode. When in LUT Mode,

on power-up the IVR value is recalled into the WR. This

value remains there until completion of the first temper-

ature conversion following power-up. The temperature

is measured every tFRAME. The temperature value is

used to calculate an index that points to the corre-

sponding value in the LUT. This index is referred to as

the LUT Address Register (LUTAR) and is located at

address 08h. The value stored in the LUT at the loca-

tion pointed to by LUTAR is called LUTVAL, and this

value is stored as the WR value (WR) at address 09h

when Update Mode bit = 1. The process then repeats

itself, continuously updating the wiper setting in a

closed-loop fashion. In this mode the 72-byte LUT is

populated with wiper settings for each two-degree tem-

perature window. Valid wiper settings are 00h to 7Fh

(the MSB is ignored). Table 3 shows the memory

addresses of the LUT as well as the corresponding

temperature range for each byte in the LUT.

Table 2. LUT Mode and LUT Adder Mode Memory Map

REGISTER

IVR

CR0

CR1

LUTAR

WR

CR2

TEMP

VOLTAGE

LUT

NAME

Initial Value Register

Control Register 0

Control Register 1

LUT Address Register

LUT Value Register

Control Register 2

Temperature Result

Supply Voltage Result

Temperature Lookup

Registers

ADDRESS

(HEX)

00h

02h

03h

08h

09h*

0Ah

0Ch

0Eh

80h–C7h

VOLATILE/NV

NV (Shadowed)

Volatile

NV (Shadowed)

Volatile

Volatile

Volatile

Volatile (Read Only)

Volatile

NV

FACTORY/POWER-UP

DEFAULT

00h

00h

03h

00h

00h

00h

N/A

N/A

00h

*In LUT Mode and LUT Adder Mode, WR is accessed through memory address 09h, while IVR remains at memory address 00h.

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