ISSUED DATE :2006/02/24
REVISED DATE :
Ordering Information ( contd. )
Part Number
GSC2127-15
GSC2127-25
XXXX
XXXX
Marking
7B152
7B252
Output Voltage
1.5V
2.5V
Part Number
GSC2127-18
GSC2127-33
XXXX
XXXX
Marking
7B182
Output Voltage
1.8V
3.3V
7B332
The GSC2127 series of COMS regulators contain a PMOS pass transistor, voltage reference, error amplifier,
over-current protection, and thermal shutdown.
The P-channel pass transistor receives data from the error amplifier, over-current shutdown, and thermal
protection circuits. During normal operation, the error amplifier compares the output voltage to a precision
reference. Over-current and Thermal shutdown circuits become active when the junction temperature exceeds
140 : , or the current exceeds 2.2A. During thermal shutdown, the output voltage remains low. Normal
operation is restored when the junction temperature drops below 120 : .
The GSC2127 behaves like a current source when the load reaches 2.2A. However, if the load impedance
drops below 0.3ohms, the current drops back to 600mA to prevent excessive power dissipation. Normal
operation is restored when the load resistance exceeds 0.75ohms.
The GSC2127 is stable with an output capacitance to ground of 4.7 F or greater. Ceramic capacitors have the
lowest ESR, and will offer the best AC performance. Conversely, Aluminum Electrolytic capacitors exhibit the
highest ESR, resulting in the poorest AC response. Unfortunately, large value ceramic capacitors are
comparatively expensive. One option is to parallel a 0.1 F ceramic capacitor with a 10 F Aluminum Electrolytic.
The benefit is low ESR, high capacitance, and low overall cost.
A second capacitor is recommended between the input and ground to stabilize V
IN
. The input capacitor should
be at least 0.1 F to have a beneficial effect.
All capacitors should be placed in close proximity to the pins. A “Quiet” ground termination is desirable. This
can be achieved with a “Star” connection.
Detailed Description
External Capacitors
Enable
When EN pin is pulled low, the PMOS pass transistor shuts off, and all internal circuits are powered down. In
this state, the quiescent current is less than 2 A. This pin behaves much like an electronic switch.
100K resistor is necessary between V
EN
source and EN pin when V
EN
is high than V
IN
.
(Note: There is no internal pull-up for EN pin. It can not be floating.)
The GSC2127 includes the Power Good feature. When the output is not within D
15% of the specified voltage,
it pulls low. This can occur under the following conditions:
1) Input Voltage too low.
2) During Over-Temperature.
3) During Over-Current.
4) If output is pulled up.
(Note: PG pin is an open-drain output.)
Power Good
GSC2127
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GTM [ GTM CORPORATION ]
