MAXIM MAX6683 User Manual

General Description

The MAX6683 system supervisor monitors multiple
power-supply voltages, including its own, and also fea­tures an on-board temperature sensor. The MAX6683
converts voltages to an 8-bit code and temperatures to
an 11-bit (10-bit-plus-sign) code using an analog-to­digital converter (ADC). A multiplexer automatically
sequences through the voltage and temperature mea­surements. The digitized signals are then stored in reg­isters and compared to the over/underthreshold limits
programmed over the SMBus™/I

2

C™-compatible 2-

wire serial interface.

When a temperature measurement exceeds the pro­grammed threshold, or when an input voltage falls out­side the programmed voltage limits, the MAX6683
generates a latched interrupt output ALERT. Three
interrupt modes are available for temperature excur­sions. These are default mode, one-time interrupt
mode, and comparator mode. The ALERT output is
cleared, except for temperature interrupts generated in
comparator mode, by reading the Interrupt Status reg­ister (Table 5). The ALERT output can also be masked
by writing to the appropriate bits in the Interrupt Mask
register (Table 6) or by setting bit 1 of the Configuration
register (Table 4) to zero. The MAX6683 SMBus/I

2

C­compatible interface also responds to the SMB alert
response address.

Applications

Workstations

Servers

Networking

Telecommunications

Features

♦ Monitors Local Temperature

♦ Monitors Three External Voltages (1.8V, 2.5V, 5V

Nominal)

♦ Monitors V

CC

(3.3V Nominal)

♦ User-Programmable Voltage and Temperature

Thresholds

♦ Alert Function with Ability to Respond to SMB

Alert Response Address

♦ +2.7V to +5.5V Supply Range

♦ -40°C to +125°C Temperature Range

♦ 60Hz or 50Hz Line-Frequency Rejection

♦ Tiny 10-Pin µMAX Package

♦ MAX6683EVKIT Available

MAX6683

Temperature Sensor and

System Monitor in a 10-Pin µMAX

________________________________________________________________ Maxim Integrated Products 1

Pin Configuration

19-2226; Rev 1; 7/04

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

EVALUATION KIT

AVAILABLE

Ordering Information

SMBus is a trademark of Intel Corp.
I

2

C is a trademark of Philips Corp.

I2C/SMBus

CONTROLLER

CPU

V

CC

V

CC =

+3.3V

SCL

SDA

ADD

1.8V

IN

2.5V

IN

5V

IN

N.C.

GND

TO 1.8V

1.8V

TO 2.5V

TO 5V

0.1μF

10kΩ

ALERT

Typical Application Circuit

PART TEMP RANGE PIN-PACKAGE

MAX6683AUB -40°C to +125°C 10 µMAX

TOP VIEW

1

1.8V

IN

2

2.5V

IN

3

5V

IN

4

GND ALERT

5

10

MAX6683

9

8

7

6

V

SCL

SDA

ADDN.C.

CC

MAX6683

Temperature Sensor and
System Monitor in a 10-Pin µMAX

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.

All Voltages Referenced to GND

All Pins...................................................................-0.3V to +6.0V

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

Continuous Power Dissipation (T

A

= +70°C)

10-Pin µMAX (derate 5.6mW/°C above +70°C) ...........444mW

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

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

Storage Temperature Range .............................-65°C to +150°C

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

ELECTRICAL CHARACTERISTICS

(TA= -40°C to +125°C, unless otherwise noted. Typical values are at VCC= +3.3V, TA= +25°C.)

POWER SUPPLY

Supply Voltage V

Supply Current

Power-On Reset (POR) Voltage VCC, rising or falling edge 2 V

TEMPERATURE

Resolution Read word mode 0.125 °C

Supply Sensitivity PSS 0.7

ADC CHARACTERISTICS

Total Unadjusted Error TUE VIN > 10LSBs ±1.5 %

Differential Nonlinearity DNL VIN > 10LSBs ±1 LSB

Supply Sensitivity PSS ±1 LSB/V

Input Resistance R

Total Monitoring Cycle Time t

SCL, SDA, ADD

Logic Input Low Voltage V

Logic Input High Voltage V

Input Leakage Current I

Output Low Voltage V

ALERT

Output Low Voltage V

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

CC

I

CC

I

SD

LEAK

OL

OLA

Operating 200 500

Shutdown mode, interface inactive 10

T

= +25°C, VCC = +3.3V ±3

A

0°C ≤ TA ≤ +125°C, VCC = +3.3V ±4Accuracy

-40°C ≤ T

1.8VIN, 2.5VIN, 5V

IN

(Note 1) 200 300 ms

c

IL

V

IH

CC

VCC > 3.6V 2.6

VIN = 0 or 5V ±1µA

I

SINK

I

SINK

I

SINK

≤ +125°C, VCC = +3.3V ±6

A

≤ 3.6V 2.0

= 3mA 400 mV

= 1.2mA, VCC > 2.7V 0.3

= 3.2mA, VCC > 4.5V 0.4

2.7 5.5 V

±1.5

IN

100 150 200 kΩ

0.8 V

µA

°C

°C/V

V

V

MAX6683

Temperature Sensor and

System Monitor in a 10-Pin µMAX

_______________________________________________________________________________________ 3

Note 1: Total monitoring time includes temperature conversion and four analog input voltage conversions.
Note 2: A master device must provide at least a 300ns hold time for the SDA signal, referred to V

IL

of the SCL signal, to bridge the

undefined region of SCL’s falling edge.

Note 3: C

b

= total capacitance of one bus line in pF. Rise and fall times are measured between 0.3 ✕VCCto 0.7 ✕VCC.

Note 4: Input filters on SDA, SCL, and ADD suppress noise spikes <50ns.

ELECTRICAL CHARACTERISTICS (continued)

(TA= -40°C to +125°C, unless otherwise noted. Typical values are at VCC= +3.3V, TA= +25°C.)

TIMING (Figures 3 and 4)

Serial Clock Frequency f

Bus Free Time Between Stop
and Start

Start Condition Hold Time tHD:

Stop Condition Hold Time tSU:

Clock Low Time T

Clock High Time T

Data Setup Time tSU:

Data Hold Time tHD:

Receive SCL/SDA Minimum
Rise Time

Receive SCL/SDA Maximum
Rise Time

Receive SCL/SDA Minimum Fall
Time

Receive SCL/SDA Maximum Fall
Time

Transmit SDA Fall Time t

Pulse Width of Spike
Suppressed

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

SCL

T

BUF

STA

STO

LOW

HIGH

DAT

(Note 2) 0 0.9 µs

(Note 3)

R

(Note 3) 300 ns

R

(Note 3)

F

(Note 3) 300 ns

F

Cb = 400pF, I

F

(Note 4) 50 ns

SINK

= 3mA

t

t

t

t

t

SP

DAT

0 400 kHz

1.3 µs

0.6 µs

0.6 µs

1.3 µs

0.6 µs

100 ns

20 +

0.1C

b

20 +

0.1C

b

20 +

0.1C

b

300 ns

ns

ns

MAX6683

Temperature Sensor and
System Monitor in a 10-Pin µMAX

4 _______________________________________________________________________________________

Typical Operating Characteristics

(VCC= +3.3V, ADD = GND, TA= +25°C, unless otherwise noted.)

0

100

50

200

150

300

250

350

2.5 3.5 4.03.0 4.5 5.0 5.5

SUPPLY CURRENT vs. SUPPLY VOLTAGE

MAX6683 toc01

SUPPLY VOLTAGE (V)

SUPPLY CURRENT (μA)

INTERFACE INACTIVE

A

C

D
E

B

A: TA = +125°C
B: T

A

= +85°C

C: T

A

= +25°C

D: T

A

= 0°C

E: T

A

= -40°C

450

250

1 100 1000

SUPPLY CURRENT

vs. SCL CLOCK FREQUENCY

300

275

325

350

375

400

425

MAX6683 toc02

CLOCK FREQUENCY (kHz)

SUPPLY CURRENT (μA)

10

VCC = +5V
SCL = 3Vp-p

-4

-3

-2

-1

0

1

2

3

4

2.5 3.53.0 4.0 4.5 5.0 5.5

TEMPERATURE ERROR

vs. SUPPLY VOLTAGE

MAX6683 toc03

SUPPLY VOLTAGE (V)

TEMPERATURE ERROR (°C)

TA = +85°C

TA = 0°C

TA = -40°C

6

0

1 100 1k10 10k

TEMPERATURE ERROR

vs. SUPPLY NOISE FREQUENCY

MAX6683 toc04

SUPPLY NOISE FREQUENCY (Hz)

TEMPERATURE ERROR (°C)

1

2

3

4

5

VCC = +5V
BYPASS CAP REMOVED
200mVp-p

-5

-2

-3

-4

0

-1

4

3

2

1

5

-50 -25 0 25 50 75 100 125

TEMPERATURE ERROR

vs. TEMPERATURE

MAX6683 toc05

TEMPERATURE (°C)

TEMPERATURE ERROR (°C)

Detailed Description

The MAX6683 is a voltage and temperature monitor
designed to communicate through an SMBus/I2C inter­face with an external microcontroller (µC). A µC with no
built-in I2C or SMBus capabilities can generate SMBus
serial commands by “bit-banging” general-purpose
input-output (GPIO) pins.

The MAX6683 can monitor external supply voltages of
typically 1.8V, 2.5V, 5V, as well as its own supply volt­age and temperature. This makes it ideal for supervisor
and thermal management applications in telecommuni­cations, desktop and notebook computers, worksta­tions, and networking equipment. Voltage inputs are
converted to an 8-bit code and temperature is convert­ed to an 11-bit code. The high-order 8 bits of the tem­perature conversion can be read using a read byte
operation through the I2C interface. The full 11-bit tem­perature conversion is read using a read word opera­tion and disregarding the lower 5 bits of the low byte.
By setting bit 5 of the Configuration Register to 1, the
temperature conversion can be reduced to 9 bits with a
four-fold reduction in conversion time. In this case, the
lower 7 bits of the low byte should be disregarded; 8­bit temperature data has a resolution of 1°C/LSB, while
11-bit temperature data has a resolution of 0.125°C/
LSB. Setting bit 5 of the Configuration Register to 1
reduces the monitoring cycle time by a factor of 4. In
this case, a read word operation for temperature data
yields a 9-bit code in which the lower 7 bits of the low
byte should be disregarded. The LSB of the 9-bit tem­perature data has a value of 0.5°C.

Each input voltage is scaled down by an on-chip resis­tive voltage-divider so that its output, at the nominal
input voltage, is 3/4 of the ADC’s full-scale range, or a
decimal count of 192 (Table 3). Input voltages other
than the nominal values may be used; ensure that they
fall within the usable ranges of pins to which they are
applied. Attenuate voltages greater than 6V with an
external resistive voltage-divider.

Writing a 1 to bit 0 of the Configuration Register starts
the monitoring function. The device performs a sequen­tial sampling of all the inputs, starting with the internal
temperature sensor and continuing with 2.5VIN, 1.8VIN,
5VIN, and VCC. If the master terminates the conversion,
the sequential sampling does not stop until the sam­pling cycle is completed and the results are stored.
When it starts again, it always starts with the tempera­ture measurement.

An interrupt signal is generated when a temperature
measurement goes above the hot limit or when a volt­age measurement is either above the high limit or
below the low limit. This causes the open-drain output
ALERT to go to the active-low state and set each corre­sponding interrupt status bit (bits 0 through 4) to 1
(Table 5). The interrupt is cleared by reading the
Interrupt Status Register except for temperature inter­rupts generated in comparator mode. Reading the
Interrupt Status Register also clears the register itself,
except for temperature interrupt bits set in comparator
mode.

MAX6683

Temperature Sensor and

System Monitor in a 10-Pin µMAX

_______________________________________________________________________________________ 5

Pin Description

PIN NAME FUNCTION

11.8VINAnalog Input. Monitors 1.8V nominal supply.

22.5VINAnalog Input. Monitors 2.5V nominal supply.

35VINAnalog Input. Monitors 5V nominal supply.

4 N.C. No Connect. Not internally connected. Connect to GND to improve thermal conductivity.

5 GND Ground

6 ALERT

7 ADD

8 SDA SMBus/I2C-Compatible Serial Data Interface

9 SCL SMBus/I2C-Compatible Clock Input

10 V

CC

SMBus Alert (Interrupt) Output, Open Drain. Alerts the master that a temperature or voltage limit has been
violated.

2

SMBus/I
transaction, and the 2LSBs of the Slave Address register are detemined by ADD’s connection to GND, SDA,
SCL, or V

Supply Voltage Input, +2.7V to +5.5V. Also serves as a voltage monitor input. Bypass VCC to GND with a

0.1µF capacitor.

C-Compatible Address Select Input. ADD is sampled at the beginning of each SMBus/I2C

.

CC