MICREL MIC384-1BM, MIC384-1BMM, MIC384-2BM, MIC384-2BMM, MIC384-0BMM Datasheet

MIC384 Micrel

MIC384

Three-Zone Thermal Supervisor

Advance Information

General Description

The MIC384 is a versatile digital thermal supervisor capable
of measuring temperature using its own internal sensor and
two inexpensive external sensors or embedded silicon di­odes such as those found in the Intel Pentium III* CPU. A 2­wire serial interface is provided to allow communication with
either I2C** or SMBus* masters. The open-drain interrupt
output pin can be used as either an over-temperature alarm
or a thermostatic control signal.

Interrupt mask and status bits are provided for reduced
software overhead. Fault queues prevent nuisance tripping
due to thermal or electrical noise. A programmable address
pin permits two devices to share the bus. (Alternate base
addresses available – contact Micrel.) Superior perfor­mance, low power and small size makes the MIC384 an
excellent choice for multiple zone thermal management
applications.

*SMBus and Pentium III are trademarks of Intel Corporation.

**I2C is a trademark of Philips Electronics, N.V.

Ordering Information

Part Number Base Address(*
MIC384-0BM 100 100x –55°C to +125°C 8-Lead SOP
MIC384-1BM 100 101x –55°C to +125°C 8-Lead SOP Contact Factory
MIC384-2BM 100 110x –55°C to +125°C 8-Lead SOP Contact Factory
MIC384-3BM 100 111x –55°C to +125°C 8-Lead SOP Contact Factory
MIC384-0BMM 100 100x –55°C to +125°C 8-Lead MSOP
MIC384-1BMM 100 101x –55°C to +125°C 8-Lead MSOP Contact Factory
MIC384-2BMM 100 110x –55°C to +125°C 8-Lead MSOP Contact Factory
MIC384-3BMM 100 111x –55°C to +125°C 8-Lead MSOP Contact Factory

* The least-significant bit of the slave address is determined by the state of the A0 pin.

Features

• Measures Local and Two Remote Temperatures

• 2-Wire SMBus-compatible Interface

• Programmable Thermostat Settings for All Three Zones

• Open-Drain Interrupt Output Pin

• Interrupt Mask and Status Bits

• Fault Queues to Prevent Nuisance Tripping

• Low Power Shutdown Mode

• Failsafe response to diode faults

• 2.7V to 5.5V Power Supply Range

• 8-Lead SOIC and MSOP Packages

Applications

• Desktop, Server and Notebook Computers

• Power Supplies

• Test and Measurement Equipment

• Wireless Systems

• Networking/Datacom Hardware

)

Junction Temp. Range Package Notes

T ypical Application

3.3V
3 × 10k

FROM

SERIAL BUS

HOST

pull-ups

DATA
CLK
/INT
GND

MIC384

VDD

T1
T2
A0

3-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

September 2000 1 MIC384

0.1µF

2200pF

2200pF

REMOTE
DIODE

REMOTE
DIODE

MIC384 Micrel

Pin Configuration

CLK
/INT

GND

Pin Description

Pin Number Pin Name Pin Function

1 DATA Digital I/O: Open-drain. Serial data input/output.
2 CLK Digital Input: The host provides the serial bit clock on this input.
3 /INT Digital Output: Open-drain. Interrupt or thermostat output.
4 GND Ground: Power and signal return for all IC functions.
5 T2 Analog Input: Connection to remote temperature sensor (diode junction)
6 T1 Analog Input: Connection to remote temperature sensor (diode junction)
7 A0 Digital Input: Slave address selection input. See Table 1. MIC284 Slave

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

1DATA
2
3
4

Address Setings.

8 VDD

A0

7

T1

6

T2

5

MIC384 2 September 2000

MIC384 Micrel

Absolute Maximum Ratings (Note 1)

Power Supply Voltage, V

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

Current Into Any Pin.................................................±10mA

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

CONV0

t

CONV1

Remote Temperature Inputs (T1, T2)

I

F

Address Input (A0)

V

IL

V

IH

C

IN

I

LEAK

Supply Current /INT, open, A0 = VDD or GND, 350 750 µA

CLK = DATA = high, normal mode
/INT, open, A0 = V

shutdown mode, CLK = 100kHz
/INT, open, A0 = V

shutdown mode, CLK = DATA = high

Power-On Reset Time; Note 7 VDD > V

POR

or GND, 3 µA

DD

or GND, 1 10 µA

DD

200 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

≤ +100°C, /INT open, ±1 ±2 °C

A

Note 4, 9 3V ≤ VDD ≤ 3.6V

–55°C ≤ T

≤ +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, 4, 9 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, local zone 50 80 ms
Note 7, 8

Conversion Time, remote zone
Note 7, 8 100 160 ms

Current to External Diode high level, T1 or T2 forced to 1.5V 224 400 µA

Note 7

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

September 2000 3 MIC384

MIC384 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_SET0 Default T_SET0 Value t
T_HYST0 Default T_HYST0 Value t
T_SET1 Default T_SET1 Value t
T_HYST1 Default T_HYST1 Value t
T_SET2 Default T_SET2 Value t
T_HYST2 Default T_HYST2 Value t

Serial Interface Timing (Note 7)

t

1

t

2

t

3

t

4

t

5

Low Output Voltage IOL = 3mA 0.4 V
Note 6 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 6

Interrupt Propagation Delay,
Note 7, 8 to /INT < VOL, FQ = 00, R

IOL = 6mA 0.8 V
from

TEMPx > T_SETx or TEMPx < T_HYSTx

= 10kΩ

PULLUP

t

CONV

+1

µs

Interrupt Reset Propagation Delay, from any register read to /INT > VOH, 1 µs
Note 7 R

POR
POR
POR
POR
POR
POR

= 10kΩ

PULLUP

after VDD > V
after VDD > V
after VDD > V
after VDD > V
after VDD > V
after VDD > V

POR
POR
POR
POR
POR
POR

81 81 81 °C
76 76 76 °C
97 97 97 °C
92 92 92 °C
97 97 97 °C
92 92 92 °C

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. TD is the temperature of the remote diode junction. Testing is performed using a single unit of one of the transistors listed in Table 6.
Note 6. Current into this pin will result in self-heating of the MIC384. Sink current should be minimized for best accuracy.
Note 7. Guaranteed by design over the operating temperature range. Not 100% production tested.
Note 8. t

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

CONV

= t

CONV0

+(2 X t

CONV1

). t

is the conversion time for the local zone; t

CONV0

is the conversion time for the remote zones.`

CONV1

MIC384 4 September 2000

MIC384 Micrel

Note 9. Accuracy specification does not include quantization noise, which may be as great as ±1⁄2LSB (±0.5°C).

Timing Diagram

t

1

SCL

SDA Data In

SDA Data Out

t

4

t

2

Serial Interface Timing

t

3

t

5

September 2000 5 MIC384

MIC384 Micrel

Functional Diagram

VDD

8-Bit Sigma-Delta ADC

T1
T2

3:1

MUX

∑

∫

DATA

CLK

A0

MIC384

Bandgap

Sensor

and

Reference

2-Wire

Serial Bus

Interface

Pointer

Register

1-Bit
DAC

Registers

Temperature

Setpoint

Registers

Temperature

Hysteresis

Registers

Configuration

Register

Result

GND

Digital Filter

and

Control

Logic

State

Machine

and

Digital

Comparator

Open-Drain

Output

/INT

Functional Description

Pin Descriptions
VDD: Power supply input. See electrical specifications.
GND: Ground return for all MIC384 functions.
CLK: Clock input to the MIC384 from the two-wire serial bus.

The clock signal is provided by the 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 bi-directional 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.

A0: This inputs sets the least significant bit of the MIC384’s
7-bit slave address. The six most-significant bits are fixed
and are determined by the part number ordered. (See order­ing information table above.) Each MIC384 will only respond
to its own unique slave address, allowing up to eight MIC384’s
to share a single bus. A match between the MIC384’s
address and the address specified in the serial bit stream
must be made to initiate communication. A0 should be tied
directly to VDD or ground. See "Temperature Measurement

and Power On" for more information. A0 determines the slave
address as shown in Table 1:

rebmuNtraP

0-483CIM0 0001001

1-483CIM0 0101001

2-483CIM0 0011001

3-483CIM0 0111001

stupnIsserddAevalS483CIM

0AyraniBxeH

b

11001001

11101001

11011001

11111001

b
b
b
b
b
b
b

84

h

94

h

A4

h

B4

h

C4

h

D4

h

E4

h

F4

h

Table 1. MIC384 Slave Address Settings

/INT: Temperature events are indicated to external circuitry

via this output. Operation of the /INT output is controlled by
the MODE and IM bits in the MIC384’s configuration register.
See "Comparator and Interrupt Modes" below. This output is
open-drain and may be wire-OR’ed 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

MIC384 6 September 2000

MIC384 Micrel

set, it prevents the /INT output from sinking current. In I
and SMBus systems, the IM bit is therefore an interrupt mask
bit.

T1 and T2: The T1 and T2 pins connect to off-chip PN diode
junctions, for monitoring the temperature at remote locations.
The remote diodes may be embedded thermal sensing
junctions in integrated circuits so equipped (such as Intel's
Pentium III), or discrete 2N3906-type bipolar transistors with
base and collector tied together.

Temperature Measurement

The temperature-to-digital converter is built around a switched
current source and an eight-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 the internal or one of the external diode junctions. The
MIC384 uses two’s-complement data to represent tempera­tures. If the MSB of a temperature value is zero, the
temperature is zero or positive. If the MSB is one, the
temperature is negative. More detail on this is given in the
"Temperature Data Format" section below. A “temperature
event” results if the value in any of the temperature result
registers (TEMPx) becomes greater than the value in the
corresponding temperature setpoint register (T_SETx). An­other temperature event occurs if and when the measured
temperature subsequently falls below the temperature hys­teresis setting in T_HYSTx.

During normal operation the MIC384 continuously performs
temperature-to-digital conversions, compares the results
against the setpoint and hysteresis registers, and updates
the state of /INT and the status bits accordingly. The remote
zones are converted first, followed by the local zone
(T1⇒T2⇒LOCAL). The states of /INT and the status bits are
updated after each measurement is taken.

Diode Faults

The MIC384 is designed to respond in a failsafe manner to
hardware faults in the external sensing circuitry. If the

C

value less than 127°C (7F
be generated on /INT if so enabled. The temperature
reported for the external zone will remain +127°C until the
fault condition is cleared. This fault detection mechanism
requires that the MIC384 complete the number of conversion
cycles specified by Fault_Queue (see below). The part will
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 MIC384 uses standard SMBus Write_Byte and
Read_Byte operations for communication with its host. The
SMBus Write_Byte operation involves sending the device’s
slave address (with the R/W bit low to signal a write opera­tion), followed by a command byte and a data byte. 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 MIC384,
followed by a repeat of the slave address with the R/W bit
(LSB) set to the high (read) state. The data to be read from
the part may then be clocked out.

The command byte is eight bits wide. This byte carries the
address of the MIC384 register to be operated upon, and is
stored in the part’s pointer register. The pointer register is an
internal write-only register. The command byte (pointer
register) values corresponding to the various MIC384 regis­ters are shown in Table 2. Command byte values other than
those explicitly shown are reserved, and should not be used.
Any command byte sent to the MIC384 will persist in the
pointer register indefinitely until it is overwritten by another
command byte. If the location latched in the pointer register
from the last operation is known to be correct (i.e., points to
the desired register), then the Receive_Byte procedure may
be used. To perform a Receive_Byte, the host sends an
address byte to select the MIC384, and then retrieves the
data byte. Figures 1 through 3 show the formats for these
procedures.

= 0111 1111b). An interrupt will

h

2

connection to an external diode is lost or the sense line (T1
or T2) is shorted to V

or ground, the temperature data

DD

reported by the A/D converter will be forced to its full-scale
value (+127°C). This will cause a temperature event to occur
if the setpoint register for the corresponding zone is set to any

etyB_dnammoCretsigeRtegraT

yraniBxeHlebaLnoitpircseD

00000000

b

10000000

b

01000000

b

11000000

b

00001000

b

01001000

b

11001000

b

00000100

b

01000100

b

11000100

b

00

h

10

h

20

h

30

h

01

h

21

h

31

h

02

h

22

h

32

h

0PMETerutarepmetlacol

GIFNOCretsigernoitarugifnoc

0TSYH_Tsiseretsyherutarepmetlacol

0TES_Ttniopteserutarepmetlacol

1PMETerutarepmet1enozetomer

1TSYH_Tsiseretsyherutarepmet1enozetomer

1TES_Ttniopteserutarepmet1enozetomer

2PMETerutarepmet2enozetomer

2TSYH_Tsiseretsyherutarepmet2enozetomer

2TES_Ttniopteserutarepmet2enozetomer

Table 2. MIC384 Register Addresses

September 2000 7 MIC384