IMP37 IMP Inc, IMP37 Datasheet - Page 4

• Manufacturer Part Number: IMP37
• Description: Low Dropout Positiv Voltage Regulators
• Manufacturer: IMP Inc

The IMP37 voltage regulator ICs offer self-protection features
which include short-circuit current protection and automatic thermal
shutdown (for junction temperature above 165°C).
Circuit Stability
Like all regulators, an output filter capacitor is required for circuit sta-
bility. Besides smoothing the output, the output capacitor
“completes” the regulator’s frequency compensation. The ESR of the
output capacitor should be less than 0.5 . Low ESR capacitors are
preferred.
Table 1 shows recommended minimum capacitance values for both
aluminum and tantalum capacitors. Larger values of output capaci-
tance do not cause stability problems.
Table 1. Recommended Output Bypass Capacitors
An input bypass capacitor is recommended. A 10 F or larger tanta-
lum capacitor is suitable for most applications.
4
Application Information
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Thermal Management
The maximum operating junction temperature for the IMP37 devices
is 150°C. The junction temperature can be calculated when the
power dissipation and ambient temperature are known with this
equation: T
The thermal resistance from juntion-to-ambient (
the three thermal resistances:
Where
Table 2. Thermal Resistance of Packages
The IMP37 series devices have thermal limiting circuitry to protect
the device from over current. For continuous operation, the maxi-
mum junction temperature rating must not be exceeded.
V
SA
JA
TS
JT
P
IN
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=
= Junction-to-Tab thermal resistance
= Tab-to-Heat Sink thermal resistance
= Heat Sink-to-Air thermal resistance
S
= T
T
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** 10 F Tantalum or 100 F Aluminum
T
* Min. 15 F Tantalum or 100 F Aluminum.
A
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Figure 1. Fixed 3.3V Regulator
2 -
Capacitor May Be Increased Without Limit.
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