500mA LDO Regulator
JAN. 2010
Product Description
The GS2905 is a 500mA fixed output voltage, low
dropout linear regulator with high ripple rejection
ratio and fast turn-on time.
It includes a reference voltage source, an error
amplifier, driver transistors and an internal current
limiter. The current limiter’s holdback circuit
operates as a short protection.
The GS2905 works well with low ESR ceramic
capacitors, suitable for wireless battery-powered
applications with stringent space requirements and
demanding performance. It also offers low
quiescent current.
Features
Wide 2.5V to 7V Operating Range
Quick Start-Up
Current Limiting Protection
Thermal Shutdown Protection
Low Dropout : 110mV @ 300mA; V
OUT
= 5V
High Ripple Rejection 55dB@10Hz
Standby Current Less Than 0.1μA
Applications
Battery-Powered Equipment
Portable Instruments
Slim DVDs
Digital Camera
WLAN Communication
Hand-Held Instruments
Typical Application Circuit
Figure1. Fixed Operation
Figure2. Adjustable Operation
Block Diagram
GS2905
1
Packages & Pin Assignments
SOT-23-5L
Pin No
.
1
2
3
4
5
SOT-89
Pin No
.
2,4,
TAB
1
-
-
3
SOT-223
Pin No.
2,4,
TAB
1
-
-
3
Pin Define
Symbol
V
IN
GND
EN
ADJ
V
OUT
Description
Input
Ground
Chip Enable
Pin
Feedback Pin
(Adjustable
Version Only)
Output Pin
Ordering Information
Marking Information
GS2905
2
Absolute Maximum Ratings
Absolute Maximum Ratings
(Note 1)
Supply Voltage V
IN
Power Dissipation, PD @ TA=25ºC
SOP-08
SOT-23
SOT-89
SOT-223
Thermal Resistance,
θja
SOP-08
SOT-23
SOT-89
SOT-223
Lead Temperature
Storage Temperature
160ºC/W
250ºC/W
175ºC/W
135ºC/W
260ºC
-65ºC to 150ºC
625mW
400mW
570mW
740mW
8V
Recommended Operating Conditions
Input Voltage VIN
EN Input Voltage
Junction Temperature
Ambient Operating Temperature
2.5V to 7V
0V to 7V
-40ºC to 125ºC
-40ºC to 85ºC
GS2905
3
Electrical Characteristics
T
A
= 25 ºC, Unless otherwise noted. V
OUT
(T) =2.0 (Note 1)
Symbo
l
Parameter
Operating Voltage Range
Shutdown Supply Current
Supply Current Limit
Quiescent Current
Conditions
V
EN
= GND,Shutdown
R
LOAD
= 1Ω
V
EN
≥
1.2V, I
OUT
= 0mA
Vout = 1.5V
Vout = 1.8V
I
OUT
=600mA
Vout = 2.5V
Vout = 2.8V
Vout = 3.3V
Vout = 5.0V
I
OUT
=300mA
Vout = 5.0V
Min
2.5
Typ
0.01
800
90
1000
800
600
350
250
230
110
0
Max
7
1
150
1500
1000
750
450
400
350
200
100
6
55
100
Unit
V
μA
mA
μA
mV
mV
mV
mV
mV
mV
mV
nA
mV/V
mV
µVRMS
ºC
ºC
V
IN
I
SBY
I
LIMIT
I
Q
V
DROP
Dropout Voltage (Note 3)
I
IBSD
∆V
LINE
∆V
LOAD
eNO
T
SD
∆T
SD
∆V
OUT
V
IL
V
IH
PSRR
EN input Bias Current
Line regulation
Load Regulation
Output Noise Voltage
Thermal Shutdown
Temperature
Thermal Shutdown
Temperature Hysteresis
Output Voltage Accuracy
EN Threshold
Power Supply
Rejection
Rate
V
EN
= GND or V
IN
V
IN
= (V
OUT
+1V) to 6V,
I
OUT
= 1mA
1mA < I
OUT
< 600mA
10Hz to 100KHz,I
OUT
=200mA,
C
OUT
= 1µF
165
30
I
OUT
=1mA
V
IN
= 2.5V to 6V,Shutdown
V
IN
= 2.5V to 6V,Start-Up
C
OUT
= 1µF, I
OUT
= 10mA
-2
1.6
55
+2
0.4
%
V
V
dB
Logic-Low V
Logic-High V
f = 10Hz
Note 1:
Stresses listed as the above “Absolute Maximum Ratings” may cause permanent damage to
the device. These are for stress ratings. Functional operation of the device at these or any
other conditions beyond those indicated in the operational sections of the specifications is not
implied. Exposure to absolute maximum rating conditions for extended periods may remain
possibility to affect device reliability.
Note 2:
V
IN(MIN)
=V
OUT
+V
DROPOUT
Note 3:
The dropout voltage is defined as (V
IN
-V
OUT
) when V
OUT
is 100mV below the target value of
V
OUT
.
GS2905
4
Application Information
Capacitor Selection and Regulator
Stability
Input Capacitor
An input capacitance of 1μF is required between
the device input pin and ground directly (the
amount of the capacitance may be increased
without limit). The input capacitor
MUST
be located
less than 1 cm from the device to assure input
stability.
A lower ESR capacitor allows the use of less
electrolytic) requires more capacitance. Capacitor
types (aluminum, ceramic and tantalum) can be
mixed in parallel, but the total equivalent input
capacitance/ESR must be defined as above for
stable operation. There are no requirements
for the ESR on the input capacitor, but tolerance
and temperature coefficient must be considered
when selecting the capacitor to ensure the
capacitance is 1μF over the entire operating range.
Thermal Considerations
For continuous operation, do not exceed the
Output Capacitor
The GS2905 is designed specifically to work with
very small ceramic output capacitors. The
maximum operation junction temperature 125°C.
The maximum power dissipation depends on the
thermal resistance of IC package, PCB layout, the
The ON/OFF signal may come from either CMOS
output, or an open-collector output with pull-up
resistor to the device input voltage or another logic
supply. The highlevel voltage may exceed the
device input voltage, but must remain within the
absolute maximum ratings for the EN pin.
To assure proper operation, the signal source used
to drive the EN pin must be able to swing above
and below the specified turn-on/off voltage
thresholds listed in the “Electrical Characteristics”
capacitance, while higher ESR type (like aluminum under V
IH
and V
IL
.
Enable Function
The GS2905 is shut down by pulling the EN pin low,
and turned on by driving the input high. If the
shutdown feature is not required, the EN pin should
be tied to VIN to keep the regulator on at all times
(the EN pin
MUST NOT
be left floating).
minimum capacitance recommended (temperature
rate of surroundings airflow and temperature
characteristics of X7R, X5R, Z5U or Y5V) is within
difference between junctions to ambient. The
the 1μF to 10μF range with 5mΩ to 50mΩ ESR
GND for transient stability, but it may be increased
without limit.
Where
T
J(MAX)
is the maximum operation junction
Higher capacitance values help to improve
critical because it forms a zero to provide phase
lead which is required for loop stability.
temperature 125°C,
T
A
is the ambient temperature
resistance.
transient response. The output capacitor's ESR is
and the
θ
JA
is the junction to ambient thermal
maximum power dissipation can be calculated by
range ceramic capacitor between LDO output and
following formula:
GS2905
5
