www.austriamicrosystems.com/AS5145

Revision 1.10

19 - 36

AS5145

Data Sheet - A p p l i c a t i o n I n f o r m a t i o n

9 Application Information

The benefits of AS5145 are as follows:

Complete system-on-chip

Flexible system solution provides absolute and PWM outputs simultaneously

Ideal for applications in harsh environments due to contactless position sensing

No calibration required

No temperature compensation necessary

9.1 Programming the AS5145

After power-on, programming the AS5145 is enabled with the rising edge of CSn with PDIO = high and CLK = low.

The AS5145 programming is a one-time-programming (OTP) method, based on poly silicon fuses. The advantage of this method is that a

programming voltage of only 3.3V to 3.6V is required for programming (either with 3.3V or 5V supply).

The OTP consists of 52 bits, of which 21 bits are available for user programming. The remaining 31 bits contain factory settings and a unique

chip identifier (Chip-ID).

A single OTP cell can be programmed only once. Per default, the cell is “0”; a programmed cell will contain a “1”. While it is not possible to reset

a programmed bit from “1” to “0”, multiple OTP writes are possible, as long as only unprogrammed “0”-bits are programmed to “1”.

Independent of the OTP programming, it is possible to overwrite the OTP register temporarily with an OTP write command at any time. This

setting will be cleared and overwritten with the hard programmed OTP settings at each power-up sequence or by a LOAD operation. Use

application note AN514X_10 to get more information about the programming options.

The OTP memory can be accessed in the following ways:

Load Operation: The Load operation reads the OTP fuses and loads the contents into the OTP register. A Load operation is automatically

executed after each power-on-reset.

Write Operation: The Write operation allows a temporary modification of the OTP register. It does not program the OTP. This operation can

be invoked multiple times and will remain set while the chip is supplied with power and while the OTP register is not modified with another

Write or Load operation.

Read Operation: The Read operation reads the contents of the OTP register, for example to verify a Write command or to read the OTP

memory after a Load command.

Program Operation: The Program operation writes the contents of the OTP register permanently into the OTP ROM.

Analog Readback Operation: The Analog Readback operation allows a quantifiable verification of the programming. For each pro-

grammed or unprogrammed bit, there is a representative analog value (in essence, a resistor value) that is read to verify whether a bit has

been successfully programmed or not.

9.1.1 Zero Position Programming

Zero position programming is an OTP option that simplifies assembly of a system, as the magnet does not need to be manually adjusted to the

mechanical zero position. Once the assembly is completed, the mechanical and electrical zero positions can be matched by software. Any

position within a full turn can be defined as the permanent new zero position.

For zero position programming, the magnet is turned to the mechanical zero position (e.g. the “off”-position of a rotary switch) and the actual

angular value is read.

This value is written into the OTP register bits Z35:Z46 (see Figure 13).

Note:

The zero position value may also be modified before programming, e.g. to program an electrical zero position that is 180º (half turn)

from the mechanical zero position, just add 2048 to the value read at the mechanical zero position and program the new value into the

OTP register.