VNH3SP30
THERMAL CALCULATION IN CLOCKWISE AND ANTI-CLOCKWISE OPERATION IN STEADY-
STATE MODE
HSA
ON
OFF
HSB
OFF
ON
LSA
OFF
ON
LSB
ON
OFF
TjHSAB
PdHSA x RthHS + PdLSB x
RthHSLS + Tamb
PdHSB x RthHS + PdLSA x
RthHSLS + Tamb
TjLSA
PdHSA x RthHSLS + PdLSB x
RthLSLS + Tamb
PdHSB x RthHSLS + PdLSA x
RthLS + Tamb
TjLSB
PdHSA x RthHSLS + PdLSB x
RthLS + Tamb
PdHSB x RthHSLS + PdLSA x
RthLSLS + Tamb
Thermal resistances definition (values according to the PCB heatsink area)
RthHS = RthHSA = RthHSB = High Side Chip Thermal Resistance Junction to Ambient (HSA or HSB in ON
state)
RthLS = RthLSA = RthLSB = Low Side Chip Thermal Resistance Junction to Ambient
RthHSLS = RthHSALSB = RthHSBLSA = Mutual Thermal Resistance Junction to Ambient between High Side
and Low Side Chips
RthLSLS = RthLSALSB = Mutual Thermal Resistance Junction to Ambient between Low Side Chips
THERMAL CALCULATION IN TRANSIENT MODE (*)
TjHSAB = ZthHS x PdHSAB + ZthHSLS x (PdLSA + PdLSB) + Tamb
TjLSA = ZthHSLS x PdHSAB + ZthLS x PdLSA + ZthLSLS x PdLSB + Tamb
TjLSB = ZthHSLS x PdHSAB + ZthLSLS x PdLSA + ZthLS x PdLSB + Tamb
Single pulse thermal impedance definition (values according to the PCB heatsink area)
ZthHS = High Side Chip Thermal Impedance Junction to Ambient
ZthLS = ZthLSA = ZthLSB = Low Side Chip Thermal Impedance Junction to Ambient
ZthHSLS = ZthHSABLSA = ZthHSABLSB = Mutual Thermal Impedance Junction to Ambient between High Side
and Low Side Chips
ZthLSLS = ZthLSALSB = Mutual Thermal Impedance Junction to Ambient between Low Side Chips
Pulse calculation formula
ZTHδ = RTH ⋅ δ + ZTHtp(1 – δ)
where δ = tp ⁄ T
(*) Calculation is valid in any dynamic operating condition. Pd values set by user.
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