MA780 – 8-BIT TO 12-BIT LOW-POWER ANGLE SENSOR

MA780 Rev. 1.2

MonolithicPower.com

24

8/30/2021

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ACTIVE

ACTIVE

AVERAGE

ACTIVE

IDLE

CYCLE

CYCLE

tt

I

I

I

(1

)

tt







 

(10)

New Data (ND) Pin

The new data (ND) signal has different use

cases, depending on the value of the threshold

parameter (THR). If THR = 0, this indicates the

end of an active period. The ND signal rises after

each active phase ends, and latches to indicate

that a new value is available in the output buffer

(see Figure 37).

ND (THR = 0)

SPI Out

Idle

Active

Idle

Angle Reading

Figure 37: Using the ND Pin as a Flag for Data

Updates (THR = 0)

If THR > 0, the device detects an angle change,

and the ND pin becomes a warning-on-change

(WOC) signal (see Figure 39). The reference

value used to detect a change can either be a

fixed value, or it can be configured by the user at

each WOC via register 10.

The ND flag is reset on the first SCLK rising edge

of the following actions/commands:

 Read angle

 Store registers to NVM

 Restore registers from NVM

 Clear status byte

Note that the ND flag cannot be reset with a read

ID command, or by writing or reading the

registers.

If the active time is shorter than the filter settling

time (determined by TACT and FW[3:0]), the ND

signal is not updated. This is because the output

angle value is not fully stabilized, so the output

angle is not within the required resolution (DV,

the data valid signal, has not been set to logic

high).

Figure 37 shows the timing diagram of the ND

pin when THR = 0. Figure 38 shows when the

ND signal requests a simple connection.

MA

ND

SPI

Master

Figure 38: Reading Both the SPI and ND

With a non-zero threshold, the ND signal does

not systematically rise after each new value. ND

only rises when the angle exceeds the threshold

(see Figure 39).

ND (THR > 0)

SPI Out

Idle

Active

Idle

Active

Idle

Angle Outside

Threshold

Angle Within

Threshold

Figure 39: Using the ND Pin as a WOC Signal

with a Non-Zero Threshold Setting.

If the angle exceeds the threshold in ASC mode,

the ND signal asserts high after every active

sample period (see Figure 40). In Figure 40,

vertical lines indicate the end of the active period,

while arrows indicate SPI readings.

ND

Ref

Threshold

Sensor

Out

Threshold

Figure 40: Example of ND Signal when the Angle

is Changing in ASC Mode

Threshold (THR)

The THR parameter is a relative angle coded on

8 bits (see Table 19). If THR exceeds 180°, the

ND flag is disabled.