DS1482

2 of 7

PIN

NAME

FUNCTION

Operating voltage for all circuitry that connects to the controlling

microprocessor (TXD, RXD, START, SPU, DONE pins).

3

SPU

This line is used to control the external strong pullup function. When SPU is

low, the strong pullup (PCTLZ) is high. When SPU is high and TXD is low,

PCTLZ is low.

4START

This line acts as an enable control for the DONE pin. If START is high, then

DONE reflects the filtered digital output of the current-sense comparator. If

START is low, then DONE is low.

5TXD

high, the 1-Wire bus is pulled to GND (for write-0, write-1, read, and reset

low times).

7

GND

10

I/O

1-Wire Data

12

RXD

This line returns the digital state of the 1-Wire bus, level-shifted to swing

13

DONE

This line is high only when the buffered, filtered digital output from the

current-sense comparator indicates that the downstream 1-Wire slave device

is no longer sinking high current. This signal is enabled if START is high.

14

PCTLZ

Active-low control pin for an external low-on-resistance, high-current

supply. This signal typically controls the gate of a P-channel MOSFET. This

signal is low when SPU is high and TXD is low.

16

Operating voltage for all circuitry that connects to the 1-Wire environment

(I/O and PCTLZ pins).

2, 6, 8, 9,

11, 15

N.C.

Not Connected

Figure 1. Block Diagram

RXD

TXD

DONE

I/O

PCTLZ

SPU

LEVEL-SHIFT BOUNDARY

START

Vref

+

-

GND