Datasheet
Table Of Contents
- FEATURES
- Applications
- Key Specifications
- DESCRIPTION
- Absolute Maximum Ratings
- Operating Ratings
- Temperature-to-Digital Converter Characteristics
- Logic Electrical Characteristics
- SMBus DIGITAL SWITCHING CHARACTERISTICS
- Functional Description
- CONVERSION SEQUENCE
- THE ALERT OUTPUT
- T_CRIT_A OUTPUT and T_CRIT LIMIT
- POWER ON RESET DEFAULT STATES
- SMBus INTERFACE
- TEMPERATURE DATA FORMAT
- OPEN-DRAIN OUTPUTS
- DIODE FAULT DETECTION
- COMMUNICATING with the LM90
- SERIAL INTERFACE RESET
- DIGITAL FILTER
- Fault Queue
- One-Shot Register
- LM90 REGISTERS
- COMMAND REGISTER
- LOCAL and REMOTE TEMPERATURE REGISTERS (LT, RTHB, RTLB)
- STATUS REGISTER (SR)
- CONFIGURATION REGISTER
- CONVERSION RATE REGISTER
- LOCAL and REMOTE HIGH SETPOINT REGISTERS (LHS, RHSHB, and RHSLB)
- LOCAL and REMOTE LOW SETPOINT REGISTERS (LLS, RLSHB, and RLSLB)
- REMOTE TEMPERATURE OFFSET REGISTERS (RTOHB and RTOLB)
- LOCAL and REMOTE T_CRIT REGISTERS (RCS and LCS)
- T_CRIT HYSTERESIS REGISTER (TH)
- FILTER and ALERT CONFIGURE REGISTER
- MANUFACTURERS ID REGISTER
- DIE REVISION CODE REGISTER
- Application Hints
- Revision History
LM90
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SNIS126A –MAY 2004–REVISED MARCH 2013
Command Select Address Power On Default State Register Register Function
Name
Read Address Write Address <D7:D0> binary <D7:D0> decimal
<P7:P0> hex <P7:P0> hex
NA 0Fh One Shot Writing to this register will initiate
a one shot conversion
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 0101 0101 85 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 0010 0001 33 RDR Read Stepping or Die Revision
Code
LOCAL and REMOTE TEMPERATURE REGISTERS (LT, RTHB, RTLB)
Table 1. LOCAL and REMOTE TEMPERATURE REGISTERS (LT, RTHB) (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 2. LOCAL and REMOTE TEMPERATURE REGISTERS (RTLB) (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.
STATUS REGISTER (SR)
Table 3. STATUS REGISTER (SR) (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.
D6: LHIGH: When set to “1” indicates a Local HIGH Temperature alarm.
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