LTC4213 Linear Technology, LTC4213 Datasheet - Page 12

• Manufacturer Part Number: LTC4213
• Description: Electronic Circuit Breaker
• Manufacturer: Linear Technology

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APPLICATIO S I FOR ATIO
LTC4213
The maximum load limit current is given by:
Most MOSFET data sheets have an R
with typical and maximum values but no minimum value.
Assuming a normal distribution with typical as mean, the
minimum value can be estimated as
The LTC4213 gives higher gate drive than the manufac-
turer specified gate drive for R
lower R
modulates the R
12
I
R
LIMIT MAX
DSON MIN
DSON
(
(
)
than specified. Operating temperature also
)
=
= •
DSON
R
2
V
DSON MIN
U
CB MAX
R
(
DSON NOM
value.
(
U
)
(
)
DSON
)
−
R
W
. This gives a slightly
DSON MAX
∆V
V
V
DSON
GATE
READY
Figure 2. Short Circuit Fault Timing Diagram
SENSE
(
SHORT CIRCUIT
specification
)
U
>V
V
CB
CB
A
t
FAULT
( )
( )
5
6
B
CIRCUIT BREAKER TRIPS
GATE AND READY PINS PULL LOW
Example Current Limit Calculation
An Si4410DY is used for current detection in a 5V supply
system with the LTC4213 V
The R
The R
CB TRIPS
Typical R
Maximum R
Estimated MIN R
R
R
R
R
DSON
DSON
DSON
DSON
DSON
DSON
@ 4.5V
@ 4.8V
@ 7V
@ 8V
distribution for the Si4410DY is
variation due to gate drive is
DSON
DSON
GS
GS
4213 F02
GS
GS
= 0.015Ω = 100%
= 0.0123Ω = 82% (NOM ∆V
= 0.012Ω = 80% (MAX ∆V
DSON
= 0.015Ω = 100% (spec. TYP)
= 0.014Ω = 93% (MIN ∆V
= 0.02Ω = 133.3%
= 2 • 15 – 20 = 0.010Ω = 66.7%
CB
at 25mV (I
SEL
pin grounded).
GSMAX
GSMAX
GSMAX
)
)
)
4213f