L9679E datasheet(104/127 Pages) STMICROELECTRONICS

104 / 127 page

LDEPL calculation

LDEPL could be calculated in the following way:

•

Non-Clock Spring Loops

LDEPLmax = LWire10m×2 + LEMI= 3.6µH/m×10m +7.7µH=43.7µH

•

Clock Spring Loops

LWire3m×2 +2×LCSx+LEMI− 2×kL_Cx× L_CS1×L_CS2 = 3.6µH/m×3m + 2 ×42.9µH

+7.7µH− 2×0.739×42.9µH =40.9µH

•

Clock Spring Loops with short to ground

LDEPLmax = LWire3m +LCSx+ LEMI= 1.8µH/m×3m +49.2µH+7.7µH=56µH

Figure 29. Deployment drivers diagram

ESD/EMI Protection

Squib/Pyroswitch

EMI Protection

Load

RSquib/Pyroswitch

LEMI

LCS1

RCS1

LCS2

RCS2

Clock Spring

Impedance

System Wiring Impedance

RWire 1

Wire lenght (m)

CS1 - LCS2

LWire 1

RWire 2

LWire 2

CSFx

SFx

SRx

CSRx

GADG1303180849PS

Table 28. Deployment Drivers – AC Specifications

Symbol

Parameter

Comments / Conditions

Min

Typ

Max

Unit

TDEPL

Deployment time

DCR_x(Dep_Current) =

IDEPL_LO ≥ 1.209 A rising to

1.209 A falling;

DCR_x(Dep_Current) =

IDEPL_HI ≥ 1.764 A rising to

1.764 A falling TDEPL =

DCR_x(Deploy_Time)*

TDEP_TIME_RES - TDEL_IDEP

DCR_x(Deploy_Time)*

TDEP_TIME_RES - 65

DCR_x(Deploy_Time)*

TDEP_TIME_RES

µs

TDEP_TIME_RES

DCR_x deploy time

resolution

1024/FOSC(min)

1024/

FOSC(typ)

1024/FOSC(max)

µs

TDEP_CC_RES

Deployment current

counter resolution

256/FOSC(min)

256/

FOSC(typ)

256/FOSC(max)

µs

TRISE_IDEPL

Rise time 10% - 90%

of IDEPL

SSxy = 25 V, RSQ = 2.2 ohm,

C = 22 nF L = 44 µH

µs

TDEL_IDEP

Delay time SPI_CS

to 90% IDEPL

SSxy = 25 V, RSQ = 2.2 ohm,

C = 22 nF L = 44 µH

µs

TFALL_IDEPL

Fall time 90% - 10%

IDEPL

SSxy = 25 V, RSQ = 2.2 ohm,

C = 22 nF L = 44 µH

µs

TDEL_SD_LS

Low-side shutdown

delay time (with

respect to high-side

deactivation)

µs

L9679E

Electrical characteristics

DS12485 - Rev 8

page 104/127

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