GM66150 GAMMA [Gamma Microelectronics Inc.], GM66150 Datasheet - Page 15

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

2009/5/18
Application Information (continued)
Minimum Load Current
The GM66150 regulators are specified between finite loads. If the output current is too small, leakage
currents dominate and the output voltage rises. The 5mA minimum load current swamps any expected
leakage current across the operating temperature range.
Adjustable Regulator Design
The adjustable regulator versions, GM66152 and GM66153, allow programming the output voltage
anywhere between 1.25V and the 26V maximum operating rating of the family. Two resistors are used.
Resistors can be quite large, up to 1M., because of the very high input impedance and low bias current of
the sense comparator: The resistor values are calculated by:
Where is V
varying load currents may scale the resistors to draw the minimum load current required for proper
operation.
Error Flag
GM66151 and GM66153 versions feature an Error Flag, which looks at the output voltage and signals an
error condition when this voltage drops 5% below its expected value. The error flag is an open-collector
output that pulls low under fault conditions. It may sink 10mA. Low output voltage signifies a number of
possible problems, including an over-current fault (the device is in current limit) and low input voltage. The
flag output is inoperative during over temperature shutdown conditions.
Enable Input
GM66151 and GM66152 versions feature an enable (EN) input that allows ON/OFF control of the device.
Special design allows œzeroB current drain when the device is disabled#only microamperes of leakage
current flows. The EN input has TTL/CMOS compatible thresholds for simple interfacing with logic, or may
be directly tied to ≤ 30V. Enabling the regulator requires approximately 20µA.
R1 = R2 (
OUT
the desired output voltage. Figure 2 shows component definition. Applications with widely
V
1.24
OUT
– 1)
Figure 2. Adjustable Regulator with Resistors
V
IN
10µF
R1
R2
1.5A ULTRA LOW DROPOUT VOLTAGE
GM66150 Series
22µF
V
OUT
REGULATORS
15