MICREL MIC184BMM, MIC184BM Datasheet

MIC184 Micrel

MIC184

Local/Remote Thermal Supervisor

Advance Information

General Description

The MIC184 is a versatile digital thermal supervisor capable
of measuring temperature using either its own internal sensor
or an inexpensive external sensor. A 2-wire serial interface is
provided to allow communication with either I2C or SMBus
masters. This device is a pin-for-pin and software compatible
upgrade for the industry standard LM75.

Additional features include remote temperature measure­ment capability, and interrupt status and mask bits in the
chip’s configuration register for software polling. The open­drain interrupt output pin can be used as either an overtem­perature alarm or thermostatic control signal. Three program­mable address pins permit users to multidrop up to 8 devices
along the 2-wire bus, allowing simple distributed temperature
sensing networks. Superior performance, low power and
small size makes the MIC184 an excellent choice for the most
demanding thermal management applications.

Features

• Measures local and remote temperatures

• Pin and software backward compatible to LM75

• 9-bit sigma-delta ADC

• 2-wire I2C/SMBus compatible interface

• Programmable thermostatic settings for either internal or

external zone

• Open-drain comparator/interrupt output pin

• Interrupt mask and status bits

• Low-power shutdown mode

• Fail-safe response to diode faults

• 2.7V to 5.5V power supply range

• Up to 8 devices may share the same bus

• 8-Lead SOP and MSOP Packages

Applications

• Desktop, Server and Notebook Computers

• Printers and Copiers

• Test and measurement equipment

• Consumer electronics

Ordering Information

Part Number Temperature Range Package

MIC184BM –55°C to +125°C 8-lead SOP
MIC184BMM –55°C to +125°C 8-lead MSOP

Typical Application

3.0V to 3.6V
V

DD

3 ×

10k

Data

Clock

Interrupt

FROM

SERIAL BUS

HOST

2-Channel SMBus Temperature Measurement System

Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 [phone] • fax + 1 [phone] • http://www.micrel.com

November 2000 1 MIC184

8
1
2
3

VDD
DATA
CLK
INT

MIC184

A2/T1

A1
A0

GND

5
6
7
4

0.1µF
ceramic

2200pF

OPTIONAL
REMOTE
TEMPERATURE
SENSOR

MIC184 Micrel

Pin Configuration

CLK

INT

GND

Pin Description

Pin Number Pin Name Pin Function

1 DATA Data (Digital I/O): Open-drain. Serial data input/output.
2 CLK Clock (Digital Input): The host provides the serial bit clock on this input.
3 INT Interrupt (Digital Output): Open-drain. Interrupt or thermostat output.
4 GND Ground: Power and signal return for all IC functions.
5 A2/T1 Address Bit 2 (Digital Input): Slave address selection input. See “Slave

6 A1 Address Bit 1 (Digital Input): Slave address selection input. See “Slave

7 A0 Address Bit 0 (Digital Input): Slave address selection input. See “Slave

8 VDD Supply (Analog Input): Power supply input to the IC.

1DATA
2
3
4

Address Truth Table.”
Temperature Sensor 1 (Analog Input): Input from remote temperature sensor

(diode junction).

Address Truth Table.”

Address Truth Table.”

8 VDD

A0

7

A1

6

A2/T1

5

MIC184 2 November 2000

MIC184 Micrel

Absolute Maximum Ratings (Note 1)

Power Supply Voltage, V

Voltage on Any Pin................................–0.3V to V

Current Into Any Pin...................................................±6mA

Power Dissipation, T

A

Junction Temperature ............................................. +150°C

................................................... 6.0V

DD

+0.3V

DD

= +125°C ...............................30mW

Operating Ratings (Note 2)

Power Supply Voltage, V
Ambient Temperature Range (T
Package Thermal Resistance (θ

SOP.................................................................+152°C/W

MSOP..............................................................+206°C/W

.............................. +2.7V to +5.5V

DD

) ............-55°C to +125°C

A

)

JA

Storage Temperature ............................... –65°C to +150°C

ESD Ratings (Note 3)

Human Body Model.................................................. TBD V

Machine Model......................................................... TBD V

Soldering

Vapor Phase (60 sec.) .............................+220°C +5⁄–0°C

Infrared (15 sec.)...................................... +235°C +5⁄–0°C

Electrical Characteristics

2.7V ≤ VDD ≤ 5.5; TA = +25°C, bold values indicate –55°C ≤ TA ≤ +125°C, Note 4; unless noted.
Symbol Parameter Condition Min Typ Max Units
Power Supply

I

DD

t

POR

V

POR

V

HYST

Temperature-to-Digital Converter Characteristics

t

CONV

Remote Temperature Input (T1)

I

F

Address Inputs (A2/T1, A1, A0)

V

IL

V

IH

C

IN

I

LEAK

I

PD

Supply Current INT open, A2, A1, A0 = VDD or GND, 340 TBD µA

CLK = DATA = high, normal mode
shutdown mode, CLK = 100kHz 2.5 µA
INT open, A2, A1, A0 = V

or GND, 1 TBD µA

DD

CLK = DATA = high, shutdown mode

Power-On Reset Time VDD > V

POR

15 100 µs

Power-On Reset Voltage all registers reset to default values, 2.0 2.7 V

A/D conversions initiated

Power-On Reset Hysteresis Voltage 250 mV

Accuracy—Local Temperature 0°C ≤ T
Note 5, 6 3V ≤ VDD ≤ 3.6V

–55°C ≤ T

≤ +100°C, INT open, ±1 ±2 °C

A

≤ +125°C, INT open, ±2 ±3 °C

A

3V ≤ VDD ≤ 3.6V

Accuracy—Remote Temperature 0°C ≤ T

≤ +100°C, INT open, ±1 ±3 °C

D

Note 5, 6, 7 3V ≤ VDD ≤ 3.6V, 0°C ≤ TA ≤ +85°C

–55°C ≤ T

≤ +125°C, INT open, ±2 ±5 °C

D

3V ≤ VDD ≤ 3.6V, 0°C ≤ TA ≤ +85°C

Conversion Time, Note 5 local temperature 100 160 ms

remote temperature 200 320 ms

Current to External Diode high level 224 400 µA

Note 5

low level 7.5 14 µA

Low Input Voltage 2.7V ≤ VDD ≤ 5.5V 0.6 V
High Input Voltage 2.7V ≤ VDD ≤ 5.5V 2.0 V
Input Capacitance 10 pF
Input Current ±0.01 ±1 µA
Pulldown Current on A2/T1 A2 = VDD, flows for t

at power-up 25 µA

POR

November 2000 3 MIC184

MIC184 Micrel

Symbol Parameter Condition Min Typ Max Units
Serial Data I/O Pin (DATA)

V

OL

V

IL

V

IH

C

IN

I

LEAK

Serial Clock Input (CLK)

V

IL

V

IH

C

IN

I

LEAK

Status Output (INT)

V

OL

t

INT

t

nINT

T_SET Default T_SET Value t
HYST Default HYST Value t

Serial Interface Timing (Note 5)

t

1

t

2

t

3

t

4

t

5

Low Output Voltage IOL = 3mA 0.4 V

IOL = 6mA 0.8 V
Low Input Voltage 2.7V ≤ VDD ≤ 5.5V 0.3V
High Input Voltage 2.7V ≤ VDD ≤ 5.5V 0.7V

DD

DD

V
V

Input Capacitance 10 pF
Input current ±0.01 ±1 µA

Low Input Voltage 2.7V ≤ VDD ≤ 5.5V 0.3V
High Input Voltage 2.7V ≤ VDD ≤ 5.5V 0.7V

DD

DD

V
V

Input Capacitance 10 pF
Input current ±0.01 ±1 µA

Low Output Voltage, IOL = 3mA 0.4 V

Note 8

Interrupt Propagation Delay, from TEMP > T_SET, FQ = 00 to INT < VOL,
Note 5 R

IOL = 6mA 0.8 V

t

+1

= 10kΩ; POL bit = 0

PULLUP

CONV

µs

Interrupt Reset Propagation Delay, from any register read to INT > VOH, 1 µs
Note 5 R

POR
POR

= 10kΩ; POL bit = 0

PULLUP

after VDD > V
after VDD > V

, Note 9 80 80 80 °C

POR

, Note 9 75 75 75 °C

POR

CLK (Clock) Period 2.5 µs
Data In Setup Time to CLK High 100 ns
Data Out Stable After CLK Low 0 ns
DATA Low Setup Time to CLK Low start condition 100 ns
DATA High Hold Time stop condition 100 ns

After CLK High

Note 1. Exceeding the absolute maximum rating may damage the device.
Note 2. The device is not guaranteed to function outside its operating rating.
Note 3. Devices are ESD sensitive. Handling precautions recommended.

Note 4. Final test on outgoing product is performed at TA = TBD°C.
Note 5. Guaranteed by design over the operating temperature range. Not 100% production tested.
Note 6. Accuracy specification does not include quantization noise, which may be as great as ±1⁄2LSB (±1⁄4°C).
Note 7. TD is the temperature of the remote diode junction. Testing is performed using a single unit of one of the transistors listed in Table 5.
Note 8. Current into the INT pin will result in self-heating of the MIC184. INT pin current should be minimized for best accuracy.
Note 9. This is the decimal representation of a binary data value.

Human body model: 1.5k in series with 100pF. Machine model: 200pF, no series resistance.

Timing Diagram

t

1

SCL

t

4

t

2

SDA Input

t

3

SDA Output

Serial Interface Timing

MIC184 4 November 2000

t

5

MIC184 Micrel

0

50

100

150

200

250

300

350

400

450

500

-60

-40

-20

0

204060

80

100

120

140

SUPPLY CURRENT (µA)

TEMPERATURE (°C)

Operating I

DD

vs. Temperature

VDD = 3.3V

VDD = 5.0V

f

CLOCK

= 0Hz

0

50

100

150

200

250

300

350

400

0246

QUIESCENT CURRENT (µA)

SUPPLY VOLTAGE (V)

Shutdown Mode IDD

vs. Suply Voltage

-12

-10

-8

-6

-4

-2

0

012345678910

MEASURMENT ERROR (°C)

CAPACITANCE (nF)

Measurment Error vs.

Capcitance on T1

Typical Characteristics

Local Temperature

Measurement Error

3

2

1

0

-1

-2
VDD = 3.3V

MESUREMENT ERROR (°C)

-3

LOCAL DIODE TEMERATURE (°C)

9
8
7
6
5
4
3
2
1

SHUTDOWN CURRENT (µA)

0

0 50 100150 200250 300 350 400

0

204060

-60

-40

-20

Shutdown I

80

DD

vs. Frequency

VDD = 5.0V

VDD = 3.0V

CLOCK FREQUENCY (kHz)

100

120

140

Remote Temperature

Measurement Error

5
4
3
2
1
0

-1

-2

-3
VDD = 3.3V

-4

MESUREMENT ERROR (°C)

-5

REMOTE DIODE TEMERATURE (°C)

3.5
3

2.5
2

1.5
1

0.5

SHUTDOWN CURRENT (µA)

0

0

-40

-20

204060

-60

Shutdown Mode I

vs. Temperature

VDD = 5.0V

f

= 0Hz

CLOCK

VDD = 3.3V

0

-60

204060

-40

-20

TEMPERATURE (°C)

80

100

DD

80

100

120

120

140

140

Response to Immersion in

140

MSOP-8

120
100

80
60
40
20

0

0 5 10 15

MEASURED LOCAL TEMPERATURE (°C)

November 2000 5 MIC184

125°C Fluid Bath

SOIC-8

TIME (Sec)

Measurement Error vs.

PCB Leakage to +5V/+3.3V/GND

-10

-15

-20

-25

MEASUREMENT ERROR (°C)

-30

1x10

5
0

-5

GND

3.3V

5.0V

6

1x1071x1081x10

RESISTANCE FROM T1(Ω)

9

MIC184 Micrel

Functional Diagram

A2/T1

A1
A0

DATA

CLK

2:1

MUX

Bandgap

Sensor

and

Reference

2-Wire

Serial Bus

Interface

∑

1-Bit
DAC

Register

Temperature

Setpoint

Register

Temperature

Hysteresis

Register

Configuration

Register

Result

TEMPERATURE-TO-DIGITAL

CONVERTER

∫

Digital Filter

and

Control

Logic

State

Machine

and

Digital

Comparator

Pointer

Register

MIC184

Functional Description

Pin Descriptions

VDD

Power supply input. See electrical specifications.

GND

Ground return for all MIC184 functions.

CLK

Clock input to the MIC184 from the two-wire serial bus. The
clock signal is provided by the bus host and is shared by all
devices on the bus.

DATA

Serial data I/O pin that connects to the two-wire serial bus.
DATA is bidirectional and has an open-drain output driver. An
external pull-up resistor or current source somewhere in the
system is necessary on this line. This line is shared by all
devices on the bus.

A2/T1, A1, A0

These inputs set the three least significant bits of the MIC184’s
7-bit slave address. Each MIC184 will only respond to its own
unique slave address, allowing the use of up to eight MIC184s
on a single bus. A match between the MIC184’s address and

Thermostat

Output

INT

the address specified in the serial bit stream must be made
to initiate communication. A1 and A0 should be connected
directly to VDD or ground. When A2/T1 is used as an address
bit input, it should also be tied to VDD or ground. A2/T1 can
alternatively connect to a remote temperature sensor. When
A2/T1 is used for temperature measurements, an off-chip
diode junction must be connected between A2/T1 and ground.
In this case, internal circuitry will detect A2 as logic low,
leaving four possible slave addresses. See “Temperature
Measurement” and “Power On” for more information. A2/T1,
A1, and A0 determine the slave address as shown in Table 1.

INT

Temperature events are indicated to external circuitry via this
output. INT may be configured as active-low or active-high by
the host. Operation of the INT output is controlled by the
MODE and POL bits in the MIC184’s configuration register.
See “Comparator and Interrupt Modes” below. This output is
open-drain and may be wire-ORed with other open-drain
signals. Most systems will require a pull-up resistor or current
source on this pin. If the IM bit in the configuration register is
set, it prevents the INT output from sinking current. In I2C and
SMBus systems, the IM bit is therefore an interrupt mask bit.

MIC184 6 November 2000

MIC184 Micrel

stupnIsserddAevalS481CIM

1T/2A1A0AyraniBxeH

000 0001001
001 1001001
010 0101001
011 1101001
100 0011001
101 1011001
110 0111001
111 1111001

edoid00 0001001
edoid01 1001001
edoid10 0101001
edoid11 1101001

b
b
b
b
b
b
b
b
b
b
b
b

84

h

94

h

A4

h

B4

h

C4

h

D4

h

E4

h

F4

h

84

h

94

h

A4

h

B4

h

Table 1. MIC184 Slave Address Settings

Temperature Measurement

The temperature-to-digital converter for both internal and
external temperature data is built around a switched current
source and a 9-bit analog-to-digital converter. The tempera­ture is calculated by measuring the forward voltage of a diode
junction at two different bias current levels. An internal
multiplexer directs the current source’s output to either an
internal or external diode junction.

The MIC184 uses two’s-complement data to represent tem­peratures. If the MSB of a temperature value is 0, the
temperature is ≥ 0°C. If the MSB is 1, the temperature is < 0°.
More detail on this is given in “Temperature Data Format”
below. A

temperature event

results if the value in the tem­perature result register (TEMP) is greater than the value in
the overtemperature setpoint register (T_SET), or if it is less
than the value in the temperature hysteresis register
(T_HYST).

The value of the ZONE bit in the configuration register
determines whether readings are taken from the on-chip
sensor or from the A2/T1 input. At power-up, the ZONE bit of
the configuration register is set to zero. The MIC184 therefore
monitors its internal temperature and compares the result

against the contents of T_SET and T_HYST. Setting the
ZONE bit in CONFIG will result in the MIC184 acquiring
temperature data from an external diode connected to the
A2/T1 pin. This diode may be embedded in an integrated
circuit (such as a CPU, ASIC, or graphics processor), or it
may be a diode-connected discrete transistor. Once the new
value is written to CONFIG, the A/D converter will begin a new
conversion and return temperature data from the external
zone. This data will be compared against T_SET, T_HYST,
and the state of the Fault_Queue (described below). The
internal status bit (STS) and the INT output will then be
updated accordingly. See “Applications Information” for more
details on switching between zones.

Diode Faults

The MIC184 is designed to respond in a fail-safe manner to
hardware faults in the external sensing circuitry. If the con­nection to the external diode is lost, or the sense line (A2/T1)
is shorted to VDD or ground, the temperature data reported by
the A/D converter will be forced to its full-scale value
(+127.5°C). This will cause an overtemperature event to
occur whenever T_SET ≤ +127.0°C (0 1111 1110b). An
interrupt will be generated if so enabled. The temperature
reported for the external zone will remain 0 1111 1111b =
+127.5°C until the fault condition is cleared. This fault detec­tion requires that the MIC184 complete the number of conver­sion cycles specified by Fault_Queue. The MIC184 may
therefore require one or more conversion cycles following
power-on or a transition from shutdown to normal operation
before reporting an external diode fault.

Serial Port Operation

The MIC184 uses standard SMBus WRITE_BYTE,
READ_BYTE, WRITE_WORD, and READ_WORD opera­tions for communication with its host. The SMBus
WRITE_BYTE and WRITE_WORD operations involve send­ing the device’s slave address (with the R/W bit low to signal
a write operation), followed by a command byte and one or
two data bytes. The SMBus READ_BYTE operation is simi­lar, but is a composite write and read operation: the host first
sends the device’s slave address followed by the command
byte, as in a write operation. A new “start” bit must then be
sent to the MIC184, followed by a repeat of the slave address
with the R/W bit (LSB) set to the high (read) state. The data

etyB_dnammoCretsigeRtegraT

yraniBxeHlebaLnoitpircseD

00000000

b

10000000

b

01000000

b

11000000

b

00100000

b

·

·

·

11111111

b

00

h

10

h

20

h

30

h

40

h

·

·

·

FF

h

PMETtlusererutarepmetderusaem

GIFNOCretsigernoitarugifnoc

TSYH_Tsiseretsyherutarepmet

TES_Ttniopteserutarepmetrevo

devreseresutonod

Table 2. MIC184 Register Addresses

November 2000 7 MIC184