L9908 datasheet(22/152 Pages) STMICROELECTRONICS

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Figure 8. Internal supply operative range

5.1.3

VDD monitor

VDD voltage level is monitored by means of dedicated UV and an OV diagnosis. Hysteresis on thresholds and

filtering time are implemented.

If VDD ≤ VDD_uv_th occurs for an interval longer than T_por_htol_flt, INT_RST flag is set. The error flag remains

set until the failure condition is removed and the flag is cleared by SPI command. POR_ANA is set low and

internal reset is triggered.

If VDD ≥ VDD_ov_th occurs for an interval longer than T_vdd_ov, VDD_OV flag is set. The error flag remains set

until the failure condition is removed and the flag is cleared by SPI command.

Device’s functional ranges related to VDD level are represented in Figure 9.

The operative VDD monitor is safety relevant and then a self-check procedure is implemented.

Note:

All parameters are guaranteed and tested in the voltage ranges reported in Table 5 unless otherwise specified.

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

Table 12. VDD monitor electrical characteristics

Symbol

Parameter

Min

Typ

Max

Unit

Notes

VDD_uv_th

VDD under-voltage threshold

3.95

4.05

4.15

Comparator output Low to High

VDD_uv_hys

VDD under-voltage hysteresis

135

165

VDD_ov_th

VDD over-voltage threshold

5.5

Comparator output Low to High

VDD_ov_hys

VDD over-voltage hysteresis

120

170

220

T_vdd_ov_flt

VDD over-voltage detection filter time

μs

Digital filter

L9908

Functional description

DS13546 - Rev 5

page 22/152

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