Highly Programmable, Back-Biased,

Hall-Effect Switch with TPOS Functionality

ATS128LSE

13

Allegro MicroSystems, LLC

115 Northeast Cutoff

Worcester, Massachusetts 01615-0036 U.S.A.

1.508.853.5000; www.allegromicro.com

register causes its programmable parameter to change, based on

the internal programming logic.

Key

A series of voltage pulses used to select a register or mode.

Code

The number used to identify the combination of fuses

activated in a bit field, expressed as the decimal equivalent of the

binary value. The LSB of a bit field is denoted as code 1, or bit 0.

Addressing

Increasing the bit field code of a selected register

by serially applying a pulse train through the VCC pin of the

device. Each parameter can be measured during the addressing

process, but the internal fuses must be blown before the program-

ming code (and parameter value) becomes permanent.

Fuse Blowing

Applying a high voltage pulse of sufficient

duration to permanently set an addressed bit by blowing a fuse

internal to the device. Once a bit (fuse) has been blown, it cannot

be reset.

Blow Pulse

A high voltage pulse of sufficient duration to blow

the addressed fuse.

Cycling the Supply

Powering-down, and then powering-up the

supply voltage. Cycling the supply is used to clear the program-

ming settings in Try mode.

Programming Procedure

Programming involves selection of a register and mode, and then

setting values for parameters in the register for evaluation or fuse

blowing. Figure 10 provides an overview state diagram.

Register Selection

Each programmable parameter can be accessed through a specific

register. To select a register, from the Initial state, a sequence of

sequence of pulses is called the key, and uniquely identifies each

register. An example register selection key is shown in figure 7.

To simplify Try mode, the ATS128 provides a set of four virtual

tude values in an increasing or decreasing sequence. These reg-

isters also allow wrapping back to the beginning of the register

after transiting the register.

Mode Selection

The same physical registers are used for all programming modes.

To distinguish the Blow mode and Read mode, when selecting

the registers an additional pulse sequence consisting of eleven

combined register and mode keys are shown in table 3.

Try Mode

In Try mode, the bit field addressing is accomplished by apply-

in figure 7. Each pulse increases the total bit field value of the

selected parameter, increasing by one on the falling edge of each

called a code. Addressing activates the corresponding fuse loca-

tions in the given bit field by increasing the binary value of an

internal DAC, up to the maximum possible code. As the value

of the bit field code increases, the value of the programmable

pulse to determine if the desired result for the programmable

parameter has been reached. Cycling the supply voltage resets

all the locations in the bit field that have un-blown fuses to their

initial states. This should also be done before selection of a differ-

ent register in Try mode.

When addressing a parameter in Try mode, the bit field address

(code) defaults to the value 1, on the falling edge of the final reg-

wraps back to the beginning of the register, and selects code 0.

Negative Trim, Up-Counting register.

Figure 8. Try mode bit field addressing pulses.

GND

GND