MAX6575L データシートの表示（PDF） - Maxim Integrated

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MAX6575L

SOT Temperature Sensor with Multidrop Single-Wire Digital Interface

Maxim Integrated 

SOT Temperature Sensor with

Multidrop Single-Wire Digital Interface

_______________Detailed Description

The MAX6575L/H low-cost, low-current (150µA typ)

temperature sensor is ideal for interfacing with micro-

controllers or microprocessors. The MAX6575L/H is a

monostable, externally triggered temperature sensor

that uses a Temp→Delay conversion to communicate

with a µP over a single I/O line. Time-select pins (TS1,

TS0) permit the internal temperature-controlled oscilla-

tor (TCO) to be scaled by four preset timeout multipli-

ers, allowing eight separate temperature sensors to

share one I/O line. Different sensors on the same I/O

line will use different timeout multipliers to avoid over-

lapping signals.

Operating the MAX6575L/H

Figure 1 illustrates the timing for the MAX6575L/H.

When the device is powered up, it assumes a ready

state where it awaits an external trigger at the I/O pin.

The I/O pin of the MAX6575L/H has an open-drain out-

put structure that requires a pull-up resistor to maintain

the proper logic levels. Once the I/O pin is pulled low

and then released, control of the I/O pin is transferred

to the MAX6575L/H. The temperature conversion

begins on the falling edge of the externally triggered

pulse. The I/O line is pulled low at a later time. That time

is determined by the device temperature and the Time

Select pins (TS1, TS0). The I/O line remains low for

5Tµs, where T is the temperature in degrees Kelvin. The

temperature of the device is represented by the edge-

to-edge delay of the externally triggered pulse and the

falling edge of the subsequent pulse originating from

the device. The device can be manually reset by

pulling the I/O line low for more than tRESET (16ms

max). The device will automatically reset after a maxi-

Table 1. Time-Select Pin Configuration

TIME-SELECT PINS

TS1

GND

GND

VDD

VDD

TS0

GND

VDD

GND

VDD

TIMEOUT MULTIPLIERS

(µs/°K)

MAX6575L MAX6575H

5

160

20

320

40

480

80

640

mum delay of 520ms, at which point it will again be in a

ready state awaiting a start pulse.

Definition of Terms:

tRESET: Time I/O must be externally pulled low to guar-

antee the MAX6575L/H is in a ready state

awaiting external trigger. (Part will assume a

ready state after 520ms without a reset pulse.)

tSETUP: Time I/O must be high prior to a start pulse.

tSTART: Trigger pulse which starts the on-chip timing

sequence on its falling edge.

tDx: Timing delay between the falling edge of the

start pulse and the falling edge initiated by

CHIP#x.

tLx: I/O pulse low time (5Tµs).

tREADY: Time after falling edge of start pulse when the

MAX6575L/H will reset itself and await the next

external trigger.

The temperature, in degrees Celsius, may be calculat-

ed as follows:

T(°C) = [tDx(µs) / timeout multiplier(µs/°K)] - 273.15°K

tSETUP

APPLIED START CHIP# 1

PULSE

RESPONSE

CHIP# 2

RESPONSE

CHIP# 3

RESPONSE

CHIP# 4

RESPONSE

tSTART

tL1

tL2

tL3

tL4

tRESET

tD1

tD2

tD3

tD4

tREADY

Figure 1. Timing Diagram

4 _______________________________________________________________________________________

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