L9908 datasheet(101/152 Pages) STMICROELECTRONICS

101 / 152 page

Figure 76. Actuation Timers timing diagram on ACT (positive & negative polarity)

The content of the count is stored into a dedicated 11bit SPI read-only register ACTn.

Reconstruction formula:

TON−OFF=ΔACT_LSB×DACTn

(24)

Where: DACTn is the digital word stored in ACTn and ∆ACT_LSB is the ACT counter quantization step.

Example:

DACTn = 10001010101 (binary) à 1109 (decimal)

ACT_CFG = 01

TON_PVF = 1109 *0.4 μs = 443.6 us ±50 ns

In case the measured time window will exceed the maximum count allowed the counter overflow is flagged by

setting to ‘1’ a dedicated SPI read-only register ACTn_OVF.

Note:

when ACT overflow condition is reached on n-th counter the ACTn value keeps the full-scale value until another

counting window is started or the disabling of ACT function.

The ACT function can be enabled according to the following SPI bits:

Table 97. Actuation Timers enable bits

ACT_EN

Description

ACT Disabled (Default)

ACT Enabled

Table 98. Actuation Timers electrical characteristics

Symbol

Parameter

Test Condition

Min

Typ

Max

Unit

Notes

ACT_res

ACT resolution

bits

Not subject to production test

ACT_lsb

ACT LSB

0.4

μs

Not subject to production test

ACT_in_acc

ACT accuracy

CLK_SSM_EN = 0

-50

Not subject to production test

Note:

All parameters are guaranteed, and tested, in the voltage ranges reported above in Table 5 unless otherwise

specified. Where not specified the parametrical operating range equals the functional operating range.

Note:

Internal counter is a 14-bit counter with LSB equal to 50 ns. ACT readout and TSYNC configuration however are

available only through the internal counter 11MSB.

L9908

Functional description

DS13546 - Rev 5

page 101/152

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