Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is

functional, but do not guarantee performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics. The guaranteed

specifications apply only for the test conditions listed. Some performance characteristics may degrade when the device is not operated under the listed test

conditions.

Note 2: All voltages are measured with respect to GND, unless otherwise noted.

components and/or ESD protection circuitry are shown below for the LM63’s pins. The nominal breakdown voltage of D3 is 6.5 V. Care should be taken not to forward

bias the parasitic diode, D1, present on pins D+ and D−. Doing so by more than 50 mV may corrupt temperature measurements. An "X" means it exists in the circuit.

Pin Name

PIN #

D1

D2

D3

D4

D5

D6

R1

SNP

ESD CLAMP

V

DD

1X

X

D+

2

X

X

XXX

X

D−

3

X

X

XXX

X

PWM

4

X

X

X

X

ALERT/Tach

6X

X

X

X

SMBDAT

7

X

X

X

X

SMBCLK

8

X

X

Note 4: Human body model, 100 pF discharged through a 1.5 k

Ω resistor. Machine model, 200 pF discharged directly into each pin. See Figure 1 above for the ESD

Protection Input Structure.

Note 5: Thermal resistance junction-to-ambient when attached to a printed circuit board with 2 oz. foil is 168˚C/W.

Note 6: See the URL “http://www.national.com/packaging/” for other recommendations and methods of soldering surface mount devices.

Note 8: Limits are guaranteed to National’s AOQL (Average Outgoing Quality Level).

Note 9: The supply current will not increase substantially with an SMBus transaction.

Note 10: Local temperature accuracy does not include the effects of self-heating. The rise in temperature due to self-heating is the product of the internal power

dissipation of the LM63 and the thermal resistance. See (Note 5) for the thermal resistance to be used in the self-heating calculation.

SMBDAT and SMBCLK pins to a high impedance state.

1.0 Functional Description

The LM63 Remote Diode Temperature Sensor with Inte-

grated Fan Control incorporates a

∆V

sensor using a Local or Remote diode and a 10-bit plus sign

∆Σ 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

the fan. 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. 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 limits 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 di-

rected 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 mea-

sured Remote Temperature (RT) is digitally compared to the

Remote High Setpoint (RHS), the Remote Low Setpoint

(RLS), and the Remote T_CRIT Setpoint (RCS) user-

programmable temperature limits. An ALERT output will oc-

cur when the measured temperature is: (1) higher than either

the High Setpoint 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

20057005

FIGURE 1. ESD Protection Input Structure

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