MAX1617A View Datasheet(PDF) - Maxim Integrated

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MAX1617A

Remote/Local Temperature Sensor with SMBus Serial Interface

Maxim Integrated 

MAX1617A

Remote/Local Temperature Sensor

with SMBus Serial Interface

Table 5. Configuration-Byte Bit

Assignments

BIT

7 (MSB)

6

5–0

NAME

MASK

RUN/

STOP

RFU

POR

STATE

0

0

0

FUNCTION

Masks all ALERT interrupts

when high.

Standby mode control bit.

If high, the device

immediately stops

converting and enters

standby mode. If low, the

device converts in either

one-shot or timer mode.

Reserved for future use

Table 6. Status-Byte Bit Assignments

BIT

NAME

FUNCTION

7

(MSB)

6

5

4

3

2

1

0

(LSB)

BUSY

LHIGH*

LLOW*

RHIGH*

RLOW*

OPEN*

RFU

RFU

A high indicates that the ADC is busy

converting.

A high indicates that the local high-

temperature alarm has activated.

A high indicates that the local low-

temperature alarm has activated.

A high indicates that the remote high-

temperature alarm has activated.

A high indicates that the remote low-

temperature alarm has activated.

A high indicates a remote-diode

continuity (open-circuit) fault.

Reserved for future use (returns 0)

Reserved for future use (returns 0)

*These flags stay high until cleared by POR, or until the status

byte register is read.

Note that the ALERT interrupt latch is not automatically

cleared when the status flag bit is cleared.

When auto-converting, if the THIGH and TLOW 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 (especially when

converting at the fastest rate). In these circumstances, it’s

best not to rely on the status bits to indicate reversals in

long-term temperature changes and instead use a current

temperature reading to establish the trend direction.

Table 7. Conversion-Rate Control Byte

DATA

00h

01h

02h

03h

04h

05h

06h

07h

08h to

FFh

CONVERSION

RATE

(Hz)

0.0625

0.125

0.25

0.5

1

2

4

8

RFU

AVERAGE SUPPLY

CURRENT

(μA typ, at VCC = 3.3V)

30

33

35

48

70

128

225

425

—

Conversion Rate Byte

The conversion rate register (Table 7) programs the time

interval between conversions in free-running auto-convert

mode. This variable rate control reduces the supply

current in portable-equipment applications. The conversion

rate byte’s POR state is 02h (0.25Hz). The MAX1617A

looks only at the 3 LSB bits of this register, so the upper 5

bits are “don’t care” bits, which should be set to zero. The

conversion rate tolerance is ±25% at any rate setting.

Valid A/D conversion results for both channels are avail-

able one total conversion time (125ms nominal, 156ms

maximum) after initiating a conversion, whether conver-

sion is initiated via the RUN/STOP bit, hardware STBY

pin, one-shot command, or initial power-up. Changing the

conversion rate can also affect the delay until new results

are available (Table 8).

Manufacturer and Device ID Codes

Two ROM registers provide manufacturer and device ID

codes (Table 4). Reading the manufacturer ID returns

4Dh, which is the ASCII code “M” (for Maxim). Reading

the device ID returns 01h, indicating a MAX1617A device.

If READ WORD 16-bit SMBus protocol is employed (rath-

er than the 8-bit READ BYTE), the least significant byte

contains the data and the most significant byte contains

00h in both cases.

Slave Addresses

The MAX1617A appears to the SMBus as one device

having a common address for both ADC channels. The

device address can be set to one of nine different values

by pin-strapping ADD0 and ADD1 so that more than one

MAX1617A can reside on the same bus without address

conflicts (Table 9).

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