MAX6397 MAXIM [Maxim Integrated Products], MAX6397 Datasheet - Page 15

• Manufacturer Part Number: MAX6397
• Description: Overvoltage Protection Switch/Limiter Controllers Operate Up to 72V
• Manufacturer: MAXIM [Maxim Integrated Products]

An additional capacitor can be added to GATE and
GND to shift the curves as this increases ∆t1. These val-
ues are used for illustration only. Customers must verify
worst-case conditons for their specific application.
Figure 13. Maximum Power Dissipation vs. Temperature
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
0
1.455W
______________________________________________________________________________________
20
40
Overvoltage Protection Switch/Limiter
ALWAYS-ON
TEMPERATURE (°C)
60
V
µC
CC
RESET
12V IN
GPIO
80
DERATE 18.2mW/°C
ABOVE +70°C
100
120
140
IN
REG
POK
Controllers Operate Up to 72V
160
SHDN
MAX6397
GATE
GND
OUT
SET
The MAX6397 high input voltage (+72V max) provides up
to 100mA of output current at REG. Package power dissi-
pation limits the amount of output current available for a
given input/output voltage and ambient temperature.
Figure 13 depicts the maximum power dissipation curve
for the MAX6397. The graph assumes that the exposed
metal pad of the MAX6397 package is soldered to 1in
PC board copper. Use Figure 11 to determine the allow-
able package dissipation for a given ambient tempera-
ture. Alternately, use the following formula to calculate the
allowable package dissipation:
Maximum power dissipation =
1.455 - 0.0182 (T
where, 0.0182 W/°C is the MAX6397 package thermal
derating.
After determining the allowable package dissipation,
calculate the maximum output current using the follow-
ing formula:
IN
I
CONVERTER
OUT MAX
DC-DC
GND
P
(
Typical Application Circuit
DISS
OUT
A
)
OUTPUT Current Calculation
= 1.455W for T
- 70°C) for +70°C ≤ T
=
V
IN
µC
P
−
D ISS
V
REG
A
≤ +70°C
≤
100
A
≤ +125°C
mA
2
15
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