GM66102 GAMMA [Gamma Microelectronics Inc.], GM66102 Datasheet - Page 7

• Manufacturer Part Number: GM66102
• Description: 1A ULTRA LOW-DROPOUT VOLTAGE REGULATORS
• Manufacturer: GAMMA [Gamma Microelectronics Inc.]

GM66102 series is high performance whit low-dropout
voltage regulators, suitable for all moderate to high-
current voltage regulator applications. Their 350mV
dropout voltage at full load makes them especially valu-
able in battery powered systems and as high efficiency
noise filters in "post-regulator" applications. Unlike
older NPN-pass transistor designs, where the minimum
dropout voltage is limited by the base-emitter voltage
drop and collector-emitter saturation voltage, dropout
performance of the PNP output of these devices is lim-
ited merely by the low V
off for the low dropout voltage is a varying base drive
requirement. But, Gamma's PNP process reduces this
drive requirement to merely 1% of the load current.
The GM66102 series of regulators are fully protected
from damage due to fault conditions. Current limiting is
provided. This limiting is linear and output current un-
der 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 (and load) survival
even when the input voltage spikes between -20V and
+60V. When the input voltage exceeds about 35V to
40V, the overvoltage sensor temporarily disables the
regulator. The output structure of these regulators al-
lows voltages in excess of the desired output voltage to
be applied without reverse current flow. An additional
feature of this regulator family is a common pinout: a
design's current requirement may change up or down
by yet use the same board layout, as all of these regu-
lators have identical pinouts.
APPLICATION INFORMATION
Figure 9. Linear regulators require only two
V
IN
+
capacitors for operation.
V
IN
GND
CE
saturation voltage. A trade-
V
OUT
+
V
OUT
Thermal Design
Linear regulators are simple to use. The most com-
plicated design parameters to consider are thermal
characteristics. Thermal design requires the follow-
ing application-specific parameters:
First, we calculate the power dissipation of the regu-
lator from these numbers and the device parameters
from this formula:
where the ground current is approximated by 1% of
Then the heat sink thermal resistance is determined
where T
2°C/W.
The heat sink may be significantly reduced in appli-
cations where the minimum input voltage is known
and is large compared with the dropout voltage. Use
a series input resistor to drop excessive voltage and
distribute the heat between this resistor and the regu-
lator, the low dropout properties of Gamma PNP reg-
ulators allow very significant reductions in regulator
power dissipation and the associated heat sink with-
out compromising performance. When this tech-
nique is employed, a capacitor of at least 0.1µF is
needed directly between the input and regulator
ground.
I
with this formula:
OUT
Maximum ambient temperature, T
Output Current, I
Output Voltage, V
Input Voltage, V
.
J(MAX)
R
P = I
q
SA
D
125°C and R
=
IN
OUT
T
OUT
OUT
J(MAX)
P
(1.01V - V
D
- T
A
IN
(
q
R
CS
q
JC
is between 0 and
OUT
A
+ R
)
q
CS
)
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