LM99

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SNIS129D – JANUARY 2003 – REVISED MARCH 2013

Command Select Address

Power On Default State

Register

Register Function

Name

Read Address

Write Address

<D7:D0> binary

<D7:D0>

<P7:P0> hex

<P7:P0> hex

decimal

10h

NA

0000 0000

0

RTLB

Remote Temperature Low Byte

11h

11h

0000 0000

0

RTOHB

Remote Temperature Offset High

Byte

12h

12h

0000 0000

0

RTOLB

Remote Temperature Offset Low

Byte

13h

13h

0000 0000

0

RHSLB

Remote HIGH Setpoint Low Byte

14h

14h

0000 0000

0

RLSLB

Remote LOW Setpoint Low Byte

19h

19h

0110 1110

110

RCS

Remote T_CRIT Setpoint

20h

20h

0101 0101

85

LCS

Local T_CRIT Setpoint

21h

21h

0000 1010

10

TH

T_CRIT Hysteresis

B0h-BEh

B0h-BEh

Manufacturers Test Registers

BFh

BFh

0000 0000

0

RDTF

Remote Diode Temperature Filter

FEh

NA

0000 0001

1

RMID

Read Manufacturer's ID

FFh

NA

LM99 0011 0001

49

RDR

Read Stepping or Die Revision Code

LM99-1 0011 0100

52

LOCAL and REMOTE TEMPERATURE REGISTERS (LT, RTHB, RTLB)

Table 3. (Read Only Address 00h, 01h):

BIT

D7

D6

D5

D4

D3

D2

D1

D0

Value

SIGN

64

32

16

8

4

2

1

For LT and RTHB D7–D0: Temperature Data. LSB = 1°C. Two's complement format.

Table 4. (Read Only Address 10h):

BIT

D7

D6

D5

D4

D3

D2

D1

D0

Value

0.5

0.25

0.125

0

0

0

0

0

For RTLB D7–D5: Temperature Data. LSB = 0.125°C. Two's complement format.

The maximum value available from the Local Temperature register is 127; the minimum value available from the

Local Temperature register is -128. The maximum value available from the Remote Temperature register is

127.875; the minimum value available from the Remote Temperature registers is

−128.875.

Note that the remote diode junction temperature is actually 16°C higher than the Remote Temperature Register

value.

STATUS REGISTER (SR)

Table 5. (Read Only Address 02h):

D7

D6

D5

D4

D3

D2

D1

D0

Busy

LHIGH

LLOW

RHIGH

RLOW

OPEN

RCRIT

LCRIT

Power up default is with all bits “0” (zero).

D0: LCRIT: When set to “1” indicates a Local Critical Temperature alarm.

D1: RCRIT: When set to “1” indicates a Remote Diode Critical Temperature alarm.

D2: OPEN: When set to “1” indicates a Remote Diode disconnect.

D3: RLOW: When set to “1” indicates a Remote Diode LOW Temperature alarm

D4: RHIGH: When set to “1” indicates a Remote Diode HIGH Temperature alarm.

D5: LLOW: When set to “1” indicates a Local LOW Temperature alarm.

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