GQ2171 Datasheet, PDF (3/5 Pages) GTM CORPORATION – CMOS POSITIVE VOLTAGE REGULATOR

ISSUED DATE :2005/12/12
REVISED DATE :
Ordering Information ( contd. )
Part Number
GQ2171-15
GQ2171-20
GQ2171-27
GQ2171-2H
GQ2171-32
Marking
1K152
XXXX
1K202
XXXX
1K272
XXXX
1K2H2
XXXX
1K322
XXXX
Output Voltage
1.5V
2.0V
2.7V
2.85V
3.2V
Part Number
GQ2171-18
GQ2171-25
GQ2171-28
GQ2171-30
GQ2171-33
Marking
1K182
XXXX
1K252
XXXX
1K282
XXXX
1K302
XXXX
1K332
XXXX
Output Voltage
1.8V
2.5V
2.8V
3.0V
3.3V
Detailed Description
The GQ2171 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
150к, or the current exceeds 150mA. During thermal shutdown, the output voltage remains low. Normal
operation is restored when the junction temperature drops below 120к.
The GQ2171 switches from voltage mode to current mode when the load exceeds the rated output current.
This prevents over-stress. The GQ2171 also incorporates current fold-back to reduce power dissipation when
the output is short circuited. This feature becomes active when the output drops below 0.8 volts, and reduces
the current flow by 65%. Full current is restored when the voltage exceeds 0.8 volts.
External Capacitors
The GQ2171 is stable with an output capacitance to ground of 0.22 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.
A second capacitor is recommended between the input and ground to stabilize Vin. The input capacitor should
be at least 1 F to have a beneficial effect.
A large capacitor improves the AC ripple rejection, but also makes the output come up slowly. This “Soft”
turn-on is desirable in some applications to limit turn-on surges.
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.
Shutdown
When actively, pulled low, the PMOS pass transistor shuts off, and all internal circuits are powered down. In
this state, the quiescent current is less than 1 A. This pin behaves much like an electronic switch.
Characteristics Curve
3/5