Rainbow Electronics MAX6636 User Manual

General Description

The MAX6636 precision multichannel temperature sen­sor monitors its own temperature and the temperatures
of up to six external diode-connected transistors. All
temperature channels have programmable alert thresh­olds. Channels 1, 4, 5, and 6 also have programmable
overtemperature thresholds. When the measured tem­perature of a channel exceeds the respective thresh­old, a status bit is set in one of the status registers. Two
open-drain outputs, OVERT and ALERT, assert corre­sponding to these bits in the status register.

The 2-wire serial interface supports the standard system
management bus (SMBus™) protocols: write byte, read
byte, send byte, and receive byte for reading the tem­perature data and programming the alarm thresholds.

The MAX6636 is specified for a -40°C to +125°C oper­ating temperature range and is available in a 20-pin
TSSOP package.

Applications

Desktop Computers

Notebook Computers

Workstations

Servers

Features

♦ Six Thermal-Diode Inputs
♦ Local Temperature Sensor
♦ 1°C Remote Temperature Accuracy (+60°C to +100°C)
♦ Temperature Monitoring Begins at POR for Fail-

Safe System Protection

♦ ALERT and OVERT Outputs for Interrupts,

Throttling, and Shutdown

♦ STBY Input for Hardware Standby Mode
♦ Small, 20-Pin TSSOP Package
♦ 2-Wire SMBus Interface
♦ Penryn CPU-Compatible
♦ Pin- and Register-Compatible with MAX6689

MAX6636

7-Channel Precision Temperature Monitor

________________________________________________________________

Maxim Integrated Products

1

Ordering Information

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.

20

19

18

17

16

15

14

13

1

2

3

4

5

6

7

8

GND

SMBCLK

SMBDATA

DXN2

DXP2

DXN1

DXP1

V

CC

N.C.

DXN4

DXP4

DXN3

DXP3

12

11

9

10

DXP6

DXN6DXN5

DXP5

MAX6636

ALERT

OVERT

STBY

2200pF

2200pF

2200pF

2200pF

2200pF

CPU

2200pF

GPU

0.1μF

TO SYSTEM
SHUTDOWN

INTERRUPT
TO μP

DATA

CLK

+3.3V

4.7kΩ
EACH

Typical Application Circuit

19-3004; Rev 0; 12/07

SMBus is a trademark of Intel Corp.

Note: Device specified over the -40°C to +125°C temperature
range.

+

Denotes lead-free package.

Pin Configuration appears at end of data sheet.

PART

PIN­PACKAGE

MAX6636UP9A+ 20 TSSOP 1001 101 U20-2

SLAVE

ADDRESS

PKG CODE

MAX6636

7-Channel Precision Temperature Monitor

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.

VCC, SCK, SDA, ALERT, OVERT, STBY to GND ......-0.3V to +6V

DXP_ to GND..............................................-0.3V to (V

CC

+ 0.3V)

DXN2, DXN3, DXN4, DXN5, DXN6 to GND...........-0.3V to +0.8V

SDA, ALERT, OVERT Current .............................-1mA to +50mA

DXN Current .......................................................................±1mA

Continuous Power Dissipation (T

A

= +70°C)
20-Pin TSSOP

(derate 11.0mW/°C above +70°C)..............................879.1mW

Junction-to-Case Thermal Resistance (θ

JC

) (Note A)

20-Pin TSSOP...............................................................20°C/W

Junction-to-Ambient Thermal Resistance (θ

JA

) (Note A)

20-Pin TSSOP............................................................73.8°C/W

ESD Protection (all pins, Human Body Model) ................±2000V

Operating Temperature Range .........................-40°C to +125°C

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

Storage Temperature Range .............................-60°C to +150°C

Lead Temperature (soldering, 10s) .................................+300°C

ELECTRICAL CHARACTERISTICS

(VCC= +3.0V to +5.5V, V

STBY

= VCC, TA= -40°C to +125°C, unless otherwise noted. Typical values are at VCC= +3.3V and

T

A

= +25°C.) (Note 1)

Note A: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a 4-layer board.

For detailed information on package thermal considerations, refer to

Application Note 4083

at www.maxim-ic.com/thermal-tutorial.

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Supply Voltage V

Software Standby Supply Current I

Operating Current I

Temperature Resolution

Remote Temperature Accuracy VCC = 3.3V

Local Temperature Accuracy VCC = 3.3V

Supply Sensitivity of Temperature
Accuracy

Remote Channel 1 Conversion
Time

Remote Channels 2 Through 6
Conversion Time

Remote-Diode Source Current I

Undervoltage-Lockout Threshold UVLO Falling edge of V

Undervoltage-Lockout Hysteresis 90 mV

Power-On-Reset (POR) Threshold VCC falling edge 1.2 2.0 2.5 V

POR Threshold Hysteresis 90 mV

ALERT, OVERT

Output Low Voltage V

Output Leakage Current 1µA

CC

SS

CC

SMBus static 30 µA

During conversion 500 1000 µA

3.0 5.5 V

Channel 1 only 11

Other diode channels 8

TA = T

T

= +60°C to +100°C -1.0 +1.0

RJ

= T

= 0°C to +125°C -3.0 +3.0

A

RJ

TA = +60°C to +100°C -4.4 -0.4

T

= 0°C to +125°C -6.1 -0.1

A

t

CONV1

t

CONV_

RJ

OL

Resistance cancellation off 95 125 156

Resistance cancellation on 190 250 312

95 125 156 ms

High level 80 100 120

Low level 8 10 12

disables ADC 2.30 2.80 2.95 V

CC

I

= 1mA 0.3

SINK

I

= 6mA 0.5

SINK

±0.2

Bits

o

o

o

C/V

ms

µA

C

C

V

MAX6636

7-Channel Precision Temperature Monitor

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(VCC= +3.0V to +5.5V, V

STBY

= VCC, TA= -40°C to +125°C, unless otherwise noted. Typical values are at VCC= +3.3V and

T

A

= +25°C.) (Note 1)

Note 1: All parameters are tested at TA= +85°C. Specifications over temperature are guaranteed by design.
Note 2: Timing specifications are guaranteed by design.
Note 3: The serial interface resets when SCL is low for more than t

TIMEOUT

.

Note 4: A transition must internally provide at least a hold time to bridge the undefined region (300ns max) of SCL’s falling edge.

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

SMBus INTERFACE (SCL, SDA), STBY

Logic-Input Low Voltage V

Logic-Input High Voltage V

Input Leakage Current -1 +1 µA

Output Low Voltage V

Input Capacitance C

SMBus-COMPATIBLE TIMING (Figures 3 and 4) (Note 2)

Serial-Clock Frequency f

Bus Free Time Between STOP
and START Condition

START Condition Setup Time

Repeat START Condition Setup
Time

START Condition Hold Time t

STOP Condition Setup Time t

Clock Low Period t

Clock High Period t

Data Hold Time t

Data Setup Time t

Receive SCL/SDA Rise Time t

Receive SCL/SDA Fall Time t

Pulse Width of Spike Suppressed t

SMBus Timeout t

IL

IH

OL

IN

SCL

t

BUF

t

SU:STA

HD:STA

SU:STO

LOW

HIGH

HD:DAT

SU:DAT

R

F

SP

TIMEOUT

VCC = 3.0V 2.2

VCC = 5.0V 2.4

I

= 6mA 0.3 V

SINK

5pF

(Note 3) 400 kHz

f

= 100kHz 4.7

SCL

f

= 400kHz 1.6

SCL

f

= 100kHz 4.7

SCL

= 400kHz 0.6

f

SCL

90% of SCL to 90% of SDA,
f

= 100kHz

SCL

90% of SCL to 90% of SDA,
f

= 400kHz

SCL

0.6

0.6

10% of SDA to 90% of SCL 0.6 µs

90% of SCL to 90% of SDA,
f

= 100kHz

SCL

90% of SCL to 90% of SDA,
f

= 400kHz

SCL

10% to 10%, f

10% to 10%, f

= 100kHz 1.3

SCL

= 400kHz 1.3

SCL

4

0.6

90% to 90% 0.6 µs

f

= 100kHz 300

SCL

f

= 400kHz (Note 4) 900

SCL

f

= 100kHz 250

SCL

f

= 400kHz 100

SCL

f

= 100kHz 1

SCL

f

= 400kHz 0.3

SCL

050ns

SDA low period for interface reset 25 37 45 ms

0.8 V

300 ns

V

µs

µs

µs

µs

µs

ns

ns

µs

MAX6636

7-Channel Precision Temperature Monitor

4 _______________________________________________________________________________________

Typical Operating Characteristics

(VCC= 3.3V, V

STBY

= VCC, TA= +25°C, unless otherwise noted.)

SOFTWARE STANDBY SUPPLY CURRENT

vs. SUPPLY VOLTAGE

MAX6636 toc01

SUPPLY VOLTAGE (V)

STANDBY SUPPLY CURRENT (μA)

5.34.84.3

3.8

1

2

3

4

5

6

7

8

9

10

11

12

0

3.3

SUPPLY CURRENT

vs. SUPPLY VOLTAGE

MAX6636 toc02

SUPPLY VOLTAGE (V)

SUPPLY CURRENT (μA)

5.34.8

3.8 4.3

325

330

335

340

350

345

355

360

320

3.3

-4

-2

-3

0

-1

2

1

3

05025 75 100 125

REMOTE TEMPERATURE ERROR

vs. REMOTE-DIODE TEMPERATURE

MAX6636 toc03

REMOTE-DIODE TEMPERATURE (°C)

TEMPERATURE ERROR (°C)

-4

-3

-2

-1

0

1

2

3

4

0 25 50 75 100 125

LOCAL TEMPERATURE ERROR

vs. DIE TEMPERATURE

MAX6636 toc04

DIE TEMPERATURE (°C)

TEMPERATURE ERROR (°C)

REMOTE-DIODE TEMPERATURE ERROR

vs. POWER-SUPPLY NOISE FREQUENCY

MAX6636 toc05

FREQUENCY (MHz)

TEMPERATURE ERROR (°C)

-4

-3

-2

-1

0

1

2

3

4

5

-5

0.1 1

100mV

P-P

LOCAL TEMPERATURE ERROR

vs. POWER-SUPPLY NOISE FREQUENCY

MAX6636 toc06

FREQUENCY (MHz)

TEMPERATURE ERROR (°C)

0.10.01

-4

-3

-2

-1

0

1

2

3

4

5

-5

0.001 1

100mV

P-P

REMOTE TEMPERATURE ERROR

vs. COMMON-MODE NOISE FREQUENCY

MAX6636 toc07

FREQUENCY (MHz)

TEMPERATURE ERROR (°C)

10.10.01

-4

-3

-2

-1

0

1

2

3

4

5

-5

0.001 10

100mV

P-P

MAX6636

7-Channel Precision Temperature Monitor

_______________________________________________________________________________________ 5

Typical Operating Characteristics (continued)

(VCC= 3.3V, V

STBY

= VCC, TA= +25°C, unless otherwise noted.)

TEMPERATURE ERROR

vs. DXP-DXN CAPACITANCE

MAX6636 toc09

DXP-DXN CAPACITANCE (nF)

TEMPERATURE ERROR (°C)

10

-4.5

-4.0

-3.5

-3.0

-2.5

-2.0

-1.5

-1.0

-0.5

0

-5.0
1 100

Pin Description

PIN NAME FUNCTION

1 DXP1

REMOTE TEMPERATURE ERROR

vs. COMMON-MODE NOISE FREQUENCY

5

100mV

4

3

2

1

0

-1

-2

TEMPERATURE ERROR (°C)

-3

-4

-5

0.001 10

P-P

10.10.01

FREQUENCY (MHz)

Combined Current Source and A/D Positive Input for Channel 1 Remote Diode. Connect to the anode
of a remote-diode-connected temperature-sensing transistor. Leave unconnected or connect to VCC if
no remote diode is used. Place a 2200pF capacitor between DXP1 and DXN1 for noise filtering.

MAX6636 toc08

2 DXN1

3 DXP2

4 DXN2

5 DXP3

6 DXN3

7 DXP4

8 DXN4

Cathode Input for Channel 1 Remote Diode. Connect the cathode of the channel 1 remote-diode­connected transistor to DXN1. Internally connected to GND.

Combined Current Source and A/D Positive Input for Channel 2 Remote Diode. Connect to the anode
of a remote-diode-connected temperature-sensing transistor. Leave unconnected or connect to V

CC

no remote diode is used. Place a 2200pF capacitor between DXP2 and DXN2 for noise filtering.

Cathode Input for Channel 2 Remote Diode. Connect the cathode of the channel 2 remote-diode­connected transistor to DXN2.

Combined Current Source and A/D Positive Input for Channel 3 Remote Diode. Connect to the anode
of a remote-diode-connected temperature-sensing transistor. Leave unconnected or connect to VCC if
no remote diode is used. Place a 2200pF capacitor between DXP3 and DXN3 for noise filtering.

Cathode Input for Channel 3 Remote Diode. Connect the cathode of the channel 3 remote-diode­connected transistor to DXN3.

Combined Current Source and A/D Positive Input for Channel 4 Remote Diode. Connect to the anode
of a remote-diode-connected temperature-sensing transistor. Leave unconnected or connect to V

CC

no remote diode is used. Place a 2200pF capacitor between DXP4 and DXN4 for noise filtering.

Cathode Input for Channel 4 Remote Diode. Connect the cathode of the channel 4 remote-diode­connected transistor to DXN4.

if

if

MAX6636

Detailed Description

The MAX6636 is a precision multichannel temperature
monitor that features one local and six remote tempera­ture-sensing channels with a programmable alert
threshold for each temperature channel and a program­mable overtemperature threshold for channels 1, 4, 5,
and 6 (see Figure 1). Communication with the MAX6636
is achieved through the SMBus serial interface and a
dedicated alert pin. The alarm outputs, OVERT and
ALERT, assert if the software-programmed temperature
thresholds are exceeded. ALERT typically serves as an
interrupt, while OVERT can be connected to a fan, sys­tem shutdown, or other thermal-management circuitry.

ADC Conversion Sequence

In the default conversion mode, the MAX6636 starts the
conversion sequence by measuring the temperature on
channel 1, followed by 2, 3, local channel, 4, 5, and 6.
The conversion result for each active channel is stored
in the corresponding temperature data register.

In some systems, one of the remote thermal diodes may
be monitoring a location that experiences temperature
changes that occur much more rapidly than in the other
channels. If faster temperature changes must be moni-

tored in one of the temperature channels, the MAX6636
allows channel 1 to be monitored at a faster rate than
the other channels. In this mode (set by writing a 1 to bit
4 of the configuration 1 register), measurements of
channel 1 alternate with measurements of the other
channels. The sequence becomes channel 1, channel
2, channel 1, channel 3, channel 1, etc. Note that the
time required to measure all seven channels is consid­erably greater in this mode than in the default mode.

Low-Power Standby Mode

Enter software standby mode by setting the STOP bit to
1 in the configuration 1 register. Enter hardware standby
by pulling STBY low. Software standby mode disables
the ADC and reduces the supply current to approxi­mately 30µA. Hardware standby mode halts the ADC
clock, but the supply current is approximately 350µA.
During either software or hardware standby, data is
retained in memory, and the SMBus interface is active
and listening for SMBus commands. The timeout is
enabled if a START condition is recognized on SMBus.
Activity on the SMBus causes the supply current to
increase. If a standby command is received while a con­version is in progress, the conversion cycle is interrupt-

7-Channel Precision Temperature Monitor

6 _______________________________________________________________________________________

Pin Description (continued)

PIN NAME FUNCTION

Combined Current Source and A/D Positive Input for Channel 5 Remote Diode. Connect to the anode

9 DXP5

10 DXN5

11 DXN6

12 DXP6

13 STBY

14 N.C. No Connection. Must be connected to ground.

15 OVERT

16 V

17 ALERT

18 SMBDATA SMBus Serial-Data Input/Output. Connect to a pullup resistor.

19 SMBCLK SMBus Serial-Clock Input. Connect to a pullup resistor.

20 GND Ground

CC

of a remote-diode-connected temperature-sensing transistor. Leave unconnected or connect to V
no remote diode is used. Place a 2200pF capacitor between DXP5 and DXN5 for noise filtering.

Cathode Input for Channel 5 Remote Diode. Connect the cathode of the channel 5 remote-diode­connected transistor to DXN5.

Cathode Input for Channel 6 Remote Diode. Connect the cathode of the channel 6 remote-diode­connected transistor to DXN6.

Combined Current Source and A/D Positive Input for Channel 6 Remote Diode. Connect to the anode
of a remote-diode-connected temperature-sensing transistor. Leave unconnected or connect to VCC if
no remote diode is used. Place a 2200pF capacitor between DXP6 and DXN6 for noise filtering.

Active-Low Standby Input. Drive STBY logic-low to place the MAX6636 in standby mode, or logic-high
for operate mode. Temperature and threshold data are retained in standby mode.

Overtemperature Active-Low, Open-Drain Output. OVERT asserts low when the temperature of
channels 1, 4, 5, and 6 exceeds the programmed threshold limit.

Supply Voltage Input. Bypass to GND with a 0.1µF capacitor.
SMBus Alert (Interrupt), Active-Low, Open-Drain Output. ALERT asserts low when the temperature of

any channel exceeds the programmed ALERT threshold.

CC

if