LM63CIMA/NOPB National Semiconductor, LM63CIMA/NOPB Datasheet - Page 8

• Manufacturer Part Number: LM63CIMA/NOPB
• Description: IC TEMP SENSR REMOTE DIODE 8SOIC
• Manufacturer: National Semiconductor
• Series: PowerWise®r

Specifications of LM63CIMA/NOPB

• Function: Fan Control, Temp Monitor
• Topology: ADC (Sigma Delta), Comparator, Fan Speed Control, Register Bank
• Sensor Type: External & Internal
• Sensing Temperature: 0°C ~ 85°C, External Sensor
• Output Type: SMBus™
• Output Alarm: Yes
• Output Fan: Yes
• Voltage - Supply: 3 V ~ 3.6 V
• Operating Temperature: 0°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Ic Output Type: Digital
• Sensing Accuracy Range: ± 1°C
• Supply Current: 1.3mA
• Supply Voltage Range: 3V To 3.6V
• Resolution (bits): 11bit
• Sensor Case Style: SOIC
• No. Of Pins: 8
• Termination Type: SMD
• Rohs Compliant: Yes
• Filter Terminals: SMD
• Accuracy %: 1°C
• For Use With: LM63EVAL - BOARD EVALUATION LM63
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: *LM63CIMA; LM63CIMA

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1.0 Functional Description
The LM63 Remote Diode Temperature Sensor with Integrat-
ed Fan Control incorporates a ΔV
sor using a Local or Remote diode and a 10-bit plus sign ΔΣ
ADC (Delta-Sigma Analog-to-Digital Converter). The pulse-
width modulated (PWM) open-drain output, with a pull-up
resistor, can drive a switching transistor to modulate fan
speed. When the ALERT/Tach is programmed to the Tach
mode the LM63 can measure the fan speed on the pulses
from the fan’s tachometer output. The LM63 includes a smart-
tach measurement mode to accommodate the corrupted
tachometer pulses when using switching transistor drive.
When the ALERT/Tach pin is programmed to the ALERT
mode the ALERT open-drain output will be pulled low when
the measured temperature exceeds certain programmed lim-
its when enabled. Details are contained in the sections below.
The LM63's two-wire interface is compatible with the SMBus
Specification 2.0 . For more information the reader is directed
to www.smbus.org.
In the LM63 digital comparators are used to compare the
measured Local Temperature (LT) to the Local High Setpoint
user-programmable temperature limit register. The measured
Remote Temperature (RT) is digitally compared to the Re-
mote High Setpoint (RHS), the Remote Low Setpoint (RLS),
and the Remote T_CRIT Setpoint (RCS) user-programmable
temperature limits. An ALERT output will occur when the
measured temperature is: (1) higher than either the High Set-
point or the T_CRIT Setpoint, or (2) lower than the Low
Setpoint. The ALERT Mask register allows the user to prevent
the generation of these ALERT outputs.
The temperature hysteresis is set by the value placed in the
Hysteresis Register (TH).
The LM63 may be placed in a low power Standby mode by
setting the Standby bit found in the Configuration Register. In
the Standby mode continuous conversions are stopped. In
Standby mode the user may choose to allow the PWM output
signal to continue, or not, by programming the PWM Disable
in Standby bit in the Configuration Register.
The Local Temperature reading and setpoint data registers
are 8-bits wide. The format of the 11-bit remote temperature
data is a 16-bit left justified word. Two 8-bit registers, high and
low bytes, are provided for each setpoint as well as the tem-
perature reading. Two Remote Temperature Offset (RTO)
Registers: High Byte and Low Byte (RTOHB and RTOLB)
may be used to correct the temperature readings by adding
or subtracting a fixed value based on a different non-ideality
factor of the thermal diode if different from the 0.13 micron
Intel Pentium 4 or Mobile Pentium 4 Processor-M processor’s
thermal diode. See Section 4.1 Thermal Diode Non-Ideality.
1.1 CONVERSION SEQUENCE
The LM63 takes approximately 31.25 ms to convert the Local
Temperature (LT), Remote Temperature (RT), and to update
all of its registers. The Conversion Rate may be modified us-
ing the Conversion Rate Register. When the conversion rate
is modified a delay is inserted between conversions, the ac-
tual conversion time remains at 31.25 ms. Different Conver-
sion Rates will cause the LM63 to draw different amounts of
supply current as shown in
Figure
BE
2.
-based temperature sen-
8
1.2 THE ALERT/TACH PIN AS ALERT OUTPUT
The ALERT/Tach pin is a multi-use pin. In this section we will
address the ALERT active-low open-drain output function.
When the ALERT/Tach Select bit is written as a zero in the
Configuration Register the ALERT output is selected. Also,
when the ALERT Mask bit in the Configuration register is writ-
ten as zero the ALERT interrupts are enabled.
The LM63's ALERT pin is versatile and can produce three
different methods of use to best serve the system designer:
(1) as a temperature comparator (2) as a temperature-based
interrupt flag, and (3) as part of an SMBus ALERT System.
The three methods of use are further described below. The
ALERT and interrupt methods are different only in how the
user interacts with the LM63.
The remote temperature (RT) reading is associated with a
T_CRIT Setpoint Register, and both local and remote tem-
perature (LT and RT) readings are associated with a HIGH
setpoint register (LHS and RHS). The RT is also associated
with a LOW setpoint register (RLS). At the end of every tem-
perature reading a digital comparison determines whether
that reading is above its HIGH or T_CRIT setpoint or below
its LOW setpoint. If so, the corresponding bit in the ALERT
Status Register is set. If the ALERT mask bit is low, any bit
set in the ALERT Status Register, with the exception of Busy
or Open, will cause the ALERT output to be pulled low. Any
temperature conversion that is out of the limits defined in the
temperature setpoint registers will trigger an ALERT. Addi-
tionally, the ALERT Mask Bit must be cleared to trigger an
ALERT in all modes.
The three different ALERT modes will be discussed in the fol-
lowing sections.
1.2.1 ALERT Output as a Temperature Comparator
When the LM63 is used in a system in which does not require
temperature-based interrupts, the ALERT output could be
used as a temperature comparator. In this mode, once the
condition that triggered the ALERT to go low is no longer
present, the ALERT is negated
ALERT output was activated by the comparison of LT > LHS,
when this condition is no longer true, the ALERT will return
HIGH. This mode allows operation without software interven-
tion, once all registers are configured during set-up. In order
for the ALERT to be used as a temperature comparator, the
Comparator Mode bit in the Remote Diode Temperature Filter
FIGURE 2. Supply Current vs Conversion Rate
(Figure
3). For example, if the
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