L9908 datasheet(98/152 Pages) STMICROELECTRONICS

98 / 152 page

Symbol

Parameter

Test Condition

Min Typ Max Unit

Notes

OND_th_acc5

VDS monitoring thresholds

accuracy 5

VDH-SHS_n

≤ 0.081 V

SHS_n-SLS_n

≤ 0.081 V

-12

mV 0x < VDS_HS/LH_TH < 3x

T_ond_flt_acc

OND Filtering Time accuracy

CLK_SSM_EN = 0 -15

T_ond_blank_acc OND Blanking Time accuracy

CLK_SSM_EN = 0 -15

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.

5.16

Phase Voltage Feedback (PVF)

L9908 implements three symmetric hysteretic comparators to monitor the level each motor phase voltage. This

function allows a real time feedback on half bridges behavior in terms of phase voltage level and transition timing

and actual phase’s duty cycle.

Figure 73. Off State Diagnosis block diagram

Each phase voltage comparator converts the output phase voltage into a digital signal by comparing it against a

threshold proportional to VDH voltage so that:

VDH-SHS_n ≥ PVFn_th_h: PVFn is set to 1.

VDH-SHS_n ≤ PVFn_th_l: PVFn is set to 0.

PVFn_th_h and PVFn_th_l are referred to as a specific percentage of the VDH voltage and can be configured by

PVF_TH_CFG bits in the register GEN_CFG4, as follows:

Table 92. PVF threshold selection bits

PVF_TH_CFG

Description

VPVF_TH_H = VDH*0.75 (Default)

VPVF_TH_L = VDH*0.25

VPVF_TH_H = VDH*0.6

L9908

Functional description

DS13546 - Rev 5

page 98/152

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