LM2990S-5.0 National Semiconductor, LM2990S-5.0 Datasheet - Page 9

• Manufacturer Part Number: LM2990S-5.0
• Description: IC, LDO VOLT REG, -5V, 1.5A, TO-263
• Manufacturer: National Semiconductor

Specifications of LM2990S-5.0

• Primary Input Voltage: -26V
• Output Voltage Fixed: -5V
• Dropout Voltage Vdo: 600mV
• No. Of Pins: 3
• Output Current: 1.5A
• Operating Temperature Range: -40°C To +125°C
• Termination Type: SMD
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Application Hints
EXTERNAL CAPACITORS
The LM2990 regulator requires an output capacitor to main-
tain stability. The capacitor must be at least 10 μF aluminum
electrolytic or 1 μF solid tantalum. The output capacitor's ESR
must be less than 10Ω, or the zero added to the regulator
frequency response by the ESR could reduce the phase mar-
gin, creating oscillations (refer to the graph on the right). An
input capacitor, of at least 1 μF solid tantalum or 10 μF alu-
minum electrolytic, is also needed if the regulator is situated
more than 6 from the input power supply filter.
FORCING THE OUTPUT POSITIVE
Due to an internal clamp circuit, the LM2990 can withstand
positive voltages on its output. If the voltage source pulling
the output positive is DC, the current must be limited to 1.5A.
A current over 1.5A fed back into the LM2990 could damage
the device. The LM2990 output can also withstand fast posi-
tive voltage transients up to 26V, without any current limiting
of the source. However, if the transients have a duration of
9
over 1 ms, the output should be clamped with a Schottky
diode to ground.
Output Capacitor ESR
1080109
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