TWO-WIRE, PROGRAMMABLE, UNIPOLAR HALL-EFFECT SWITCH FAMILY

(PRELIMINARY INFORMATION – SUBJECT TO CHANGE)

Rev. 1.8 25 April 2003

Page 6

115 Northeast Cutoff, Box 15036

Worcester, Massachus etts 01615-0036 (508) 853-5000

Copyright © 1993, 1995 Allegro MicroSystems, Inc.

PROGRAMMING PROTOCOL

correct operate point is determined, the device programming bits are permanently blown, and a locking bit is blown to

prevent any further programming.

Switch Point Program Enable. To program the device, a keying sequence is used to activate / enable the addressing

mode as shown in Figure 1. This sequence consisting of a VPP pulse, one VPH pulse, and a VPP pulse with no supply

interruptions, is designed to prevent the device from being programmed accidentally (e.g., as a result of noise on the

supply line).

Figure 1. Program Enable Pulse Sequence.

Valid over operating temperature range unless otherwise noted.

Limits

Part Number

Characteristics

Symbol

Test Conditions

Min.

Typ.

Max.

Units

Minimum voltage range

during programming

4.5

5

5.5

V

11.5

12.5

13.5

V

Programming Voltage

6

25

26

27

V

Programming Current

-

190

-

mA

OFF time between bits

20

-

-

µs

Pulse duration for enable

and addressing

sequences

20

-

-

µs

Pulse width

Pulse duration for fuse

blowing

100

300

-

µs

Pulse Rise Time

5

-

100

µs

A118X Family

Pulse Fall Time

5

-

100

µs

6

Programming Voltages are measured at Pin #1 (Vcc) of SIP. A minimum capacitance of 0.1uF must be connected from Vcc to GND of the SIP to

provide the current necessary to blow the fuse.