GM66150 GAMMA [Gamma Microelectronics Inc.], GM66150 Datasheet - Page 14

• Manufacturer Part Number: GM66150
• Description: 1.5A ULTRA LOW DROPOUT VOLTAGE REGULATORS
• Manufacturer: GAMMA [Gamma Microelectronics Inc.]

14
Application Information
The GM66150 series is a high performance low-dropout voltage regulator suitable for all moderate to high
current/voltage regulator applications. The 350mV dropout voltage at full load makes it especially valuable
in battery powered systems and as high efficiency noise filters in “post-regulator” applications.
Unlike older NPN-pass transistor designs, dropout performance of the PNP output of these devices is
limited merely by the low VCE saturation voltage. The GM66150 family of regulators is fully protected from
damage due to fault conditions. Current limiting is provided. This limiting is linear; output current under
overload conditions is constant.
Thermal shutdown disables the device when the die temperature exceeds the 125°C maximum safe
operating temperature. Transient protection allows device survival even when the input voltage spikes
between -20V and +60V. When the input voltage exceeds about 35V to 40V, the over voltage sensor
temporarily disables the regulator.
Thermal Design
Linear regulators are simple to use. The most complicated design parameters to consider are thermal
characteristics. Thermal design requires the following application-specific parameters:
Capacitor Requirements
For stability and minimum output noise, a capacitor on the regulator output is necessary. The value of this
capacitor is dependent upon the output current; lower currents allow smaller capacitors. GM66150 series
are stable with the 10µF minimum capacitor values at full load. Where the regulator is powered from a
source with a high AC impedance, a 0.1µF capacitor connected between Input and GND is recommended.
This capacitor should have good characteristics to above 250kHz.
First, we calculate the power dissipation of the regulator from these numbers and the device
parameters from this datasheet.
Then the heat sink thermal resistance is determined with this formula:
• Maximum ambient temperature, T
• Output Current, I
• Output Voltage, V
• Input Voltage, V
P
θ
SA
D
= I
=
OUT
T
JMAX
Figure 1.Linear regulators require only two capacitors for operation.
X (1.01V
P
D
– T
A
IN
OUT
OUT
IN
– (θ
- V
JC
OUT
+θ
V
), Where the ground current is approximated by 1% of I
CS
IN
), where T
A
IN
JMAX
GND
≤125°C and θ
1.5A ULTRA LOW DROPOUT VOLTAGE
OUT
GM66150 Series
V
OUT
CS
is between 0 and 20°C/W
REGULATORS
OUT
.