MAX6658MSA+T Datasheet MAX6657MSA+, MAX6658MSA+, MAX6659MEE+ | P13-P15

MAX6657/MAX6658/MAX6659

______________________________________________________________________________________ 13

Status Byte Functions

The status byte (Table 6) indicates which (if any) tem-

perature thresholds have been exceeded. This byte also

indicates whether the ADC is converting and if there is

an open-circuit fault detected with the external sense

junction. After POR, the normal state of the MSB is 1 and

all the other flag bits are 0, assuming no alert or

overtemperature conditions are present. Bits 2 through

6 of the Status register are cleared by any successful

read of the Status register, unless the fault persists. The

ALERT output follows the status flag bit. Both are

cleared when successfully read, but if the condition still

exists, they reassert at the end of the next conversion.

The bits indicating OVERT1 (bits 0 and 1) are cleared

only when the condition no longer exists. Reading the

status byte does not clear the OVERT1 outputs or fault

bits. One way to eliminate the fault condition is for the

measured temperature to drop below the temperature

threshold minus the hysteresis value. Another way to

eliminate the fault condition is by writing new values for

the OVERT1 threshold or hysteresis so that a fault con-

dition is no longer present. Note that the status byte

does not provide status of OVERT2.

The MAX6657/MAX6658/MAX6659 incorporate collision

avoidance so that completely asynchronous operation

is allowed between SMBus operations and temperature

conversions.

When autoconverting, if the T

HIGH

and T

LOW

limits are

close together, it’s possible for both high-temp and low-

temp status bits to be set, depending on the amount of

time between status read operations. In these circum-

stances, it is best not to rely on the status bits to indi-

cate reversals in long-term temperature changes.

Instead, use a current temperature reading to establish

the trend direction.

Conversion Rate Byte

The Conversion Rate register (Table 7) programs the

time interval between conversions in free-running

autonomous mode (RUN/STOP = 0). This variable rate

BIT NAME

POR

STATE

FUNCTION

(MSB)

MASK1 0 Masks ALERT interrupts if a 1.

6 RUN/STOP 0

Standby mode control bit; if a

1, standby mode is initiated.

5 SPNP 1

Set to 1 when the remote

sensor is a substrate or

common collector PNP. Set to 0

when the remote sensor is a

diode-connected discrete

transistor.

4 to 0 RFU 0 Reserved

Table 5. Configuration-Byte Bit

Assignments

BIT NAME POR STATE FUNCTION

7 (MSB) BUSY 1 A/D is busy converting when high.

6 LHIGH 0

Internal high-temperature alarm has tripped when high; cleared by POR or readout of

the Status register if the fault condition no longer exists.

5 LLOW 0

Internal low-temperature alarm has tripped when high; cleared by POR or readout of

the Status register if the fault condition no longer exists.

4 RHIGH 0

External high-temperature alarm has tripped when high; cleared by POR or readout of

the Status register if the fault condition no longer exists.

3 RLOW 0

External low-temperature alarm has tripped when high; cleared by POR or readout of

the Status register if the fault condition no longer exists.

2 OPEN 0

A high indicates an external diode open; cleared by POR or readout of the Status

1 EOT1 0

A high indicates the external junction temperature exceeds the external OVERT1

threshold.

0 IOT1 0

A high indicates the internal junction temperature exceeds the internal OVERT1

threshold.

Table 6. Status Register Bit Assignments

±1°C, SMBus-Compatible Remote/Local Temperature

Sensors with Overtemperature Alarms

MAX6657/MAX6658/MAX6659

control can be used to reduce the supply current in

portable-equipment applications. The conversion rate

byte’s POR state is 08h (16Hz). The MAX6657/

MAX6658/MAX6659 use only the 4 least-significant bits

(LSBs) of this register. The 4 most-significant bits

(MSBs) are “don’t care” and should be set to zero when

possible. The conversion rate tolerance is ±25% at any

rate setting.

Valid A/D conversion results for both channels are

available one total conversion time (125ms nominal,

156ms maximum) after initiating a conversion, whether

conversion is initiated through the RUN/STOP bit, hard-

ware STBY pin, one-shot command, or initial power-up.

Slave Addresses

The MAX6657/MAX6658 have a fixed address of

1001100. The MAX6659 can be programmed to have

one of three different addresses, allowing up to three

devices to reside on the same bus without address

conflicts. Table 8 lists address information.

The address pin state is checked at POR only, and the

address data stays latched to reduce quiescent supply

current due to the bias current needed for high-Z state

detection.

The MAX6657/MAX6658/MAX6659 also respond to the

SMBus Alert Response slave address (see

Alert

Response Address

section).

POR and UVLO

The MAX6657/MAX6658/MAX6659 have a volatile

memory. To prevent unreliable power-supply conditions

from corrupting the data in memory and causing erratic

behavior, a POR voltage detector monitors V

and

clears the memory if V

falls below 1.7V (typ, see

Electrical Characteristics

). When power is first applied

and V

rises above 2.0V (typ), the logic blocks begin

operating, although reads and writes at V

levels

below 3.0V are not recommended. A second V

com-

parator and the ADC undervoltage lockout (UVLO)

comparator prevent the ADC from converting until there

is sufficient headroom (V

= +2.8V typ).

Power-Up Defaults

Power-up defaults include:

• ADC begins autoconverting at a 16Hz rate (legacy

resolution).

• THIGH and TLOW registers are set to default limits,

respectively.

• Interrupt latch is cleared.

• Address-select pin is sampled (MAX6659 only).

• Command register is set to 00h to facilitate quick

internal Receive Byte queries.

• Hysteresis is set to 10°C.

• Transistor type is set to a substrate or common col-

lector PNP.

14 ______________________________________________________________________________________

DATA CONVERSION RATE (Hz)

00h 0.0625

01h 0.125

02h 0.25

03h 0.5

04h 1

05h 2

06h 4

07h 8

08h 16

09h 16

0Ah-FFh Reserved

ADD CONNECTION ADDRESS

GND 1001100

1001110

Unconnected 1001101

Table 8. Slave Address Decoding for

MAX6659

Note: Extended resolution applies only for conversion rates of

4Hz or slower.

Table 7. Conversion-Rate

Control Byte

BIT NAME FUNCTION

7 (MSB) ADD7

6 ADD6

5 ADD5

4 ADD4

3 ADD3

2 ADD2

1 ADD1

Provide the current

MAX6659 slave address

that was latched at POR

(Table 8)

0 (LSB) 1 Logic 1

Table 9. Read Format for Alert Response

Address (000 1100)

±1°C, SMBus-Compatible Remote/Local Temperature

Sensors with Overtemperature Alarms

MAX6657/MAX6658/MAX6659

______________________________________________________________________________________ 15

Chip Information

PROCESS: BiCMOS

SMBDATA

SMBCLK

DATA

CLOCK

INTERRUPTED TO µP

TO FAN DRIVER

() ARE MAX6659 ONLY

TO SYSTEM SHUTDOWN

(ADD) GND

µP

3.3V

200Ω

2200pF

10kΩ

EACH

0.1µF

DXP

DXN

ALERT

OVERT1

(OVERT2)

(STBY)

MAX6657

MAX6658

MAX6659



Typical Operating Circuit

±1°C, SMBus-Compatible Remote/Local Temperature

Sensors with Overtemperature Alarms

Package Information

For the latest package outline information and land patterns, go

to www.maxim-ic.com/packages

. Note that a “+”, “#”, or “-” in

the package code indicates RoHS status only. Package draw-

ings may show a different suffix character, but the drawing per-

tains to the package regardless of RoHS status.

PACKAGE

TYPE

PACKAGE

CODE

OUTLINE NO.

LAND

PATTERN NO.

8 SO S8-5

21-0041

90-0096

16 QSOP E16-5

21-0055

90-0167

Ordering Information (continued)

PART

MEASURED TEMP

RANGE

PIN-PACKAGE

MAX6658MSA -55°C to +125°C 8 SO

MAX6658MSA+ -55°C to +125°C 8 SO

MAX6658MSA-T -55°C to +125°C 8 SO

MAX6658MSA+T -55°C to +125°C 8 SO

MAX6659MEE -55°C to +125°C 16 QSOP

MAX6659MEE+ -55°C to +125°C 16 QSOP

MAX6659MEE-T -55°C to +125°C 16 QSOP

MAX6659MEE+T -55°C to +125°C 16 QSOP

Note: All devices are specified over the -55°C to +125°C oper-

ating temperature range.

Denotes a lead(Pb)-free/RoHS-compliant package.

T = Tape and reel.

P1-P3 P4-P6 P7-P9 P10-P12 P13-P15 P16-P16

MAX6658MSA+T

Mfr. #:

Buy MAX6658MSA+T

Manufacturer:

Maxim Integrated

Description:

Board Mount Temperature Sensors Remote/Local Temperature Senso

Lifecycle:

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MAX6658MSA+T

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