GM6155
150mA LOW - NOISE LDO REGULATOR
Power Management
Description
The GM6155 is an efficient linear voltage regulator with
ultralow - noise output, very low dropout voltage (typically
17mV at light loads and 100mV at 50mA), and very low
ground current (600µA at 100mA output). The GM6155 pro-
vides better than 1% initial accuracy.
Designed especially for hand-held, battery-powered de-
vices, the GM6155 includes a CMOS or TTL compatible en-
able/ shutdown control input. When shutdown, power con-
sumption drops nearly to zero. Regulator ground current in-
creases only slightly in dropout, further prolonging battery
life. Key GM6155 features include a reference bypass pin
to improve its already excellent low-noise performance, re-
versed-battery protection, current limiting, and
overtemperature shutdown.
The GM6155 is available in SOT-25 package.
Features
Very low noise output
Extremely accurate output voltage
Guaranteed 150mA output
Low quiescent current
Low dropout voltage
Extremely tight load and line regulation
Very low temperature coefficient
Current and thermal limiting
Reverse-battery protection
"Zero" off-mode current
Logic-controlled electronic enable
Application
Cellular telephones
Laptop, notebook, and palmtop computers
Battery-powered equipment
PCMCIA V
CC
and V
PP
regulation/ switching
TYPICAL APPLICATION CIRCUITS
Revision 1, Feb. 2004
Low-Noise Operation:
C
BYP
= 470pF, C
OUT
Basic Operation:
C
BYP
= not used, C
OUT
2.2µF
1µF
www.gammamicro.com
Consumer/ personal electronics
SMPS post-regulator/ dc-to-dc modules
High-efficiency linear power supplies
2
Enable
Shutdown
3
EN
GM6155-3.3
V
IN
1
5
V
OUT
4
C
OUT
= 2.2µF
(tantalum)
C
BYP
EN (pin 3) may be connected
directly to IN (pin1).
PRELIMINARY
GM6155
1
GM6155
MARKING INFORMATION & PIN CONFIGURATIONS (TOP VIEW)
SOT-25 (SOT-23-5)
OUT
5
SOT-25 (SOT-23-5)
OUT
5
BYP
4
ADJ
4
Part
Identification
XXVYW
1
2
3
1
XXVYW
2
3
IN GND EN
IN GND EN
Fixed Voltages
Adjustable Voltage
XX
V
Y
W
= Specific Device Code
(DA = GM6155)
= Voltage Code
= Year
= Work Week
ORDERING INFORMATION
Ordering Number
GM6155-AST25R
GM6155-2.5ST25R
GM6155-2.7ST25R
GM6155-2.8ST25R
GM6155-2.9ST25R
GM6155-3.0ST25R
GM6155-3.3ST25R
GM6155-3.6ST25R
GM6155-4.0ST25R
GM6155-4.2ST25R
GM6155-5.0ST25R
Output Voltage
Voltage Code
Adj
2.5V
2.7V
2.8V
2.9V
3.0V
3.3V
3.6V
4.0V
4.2V
5.0V
A
G
T
H
X
J
K
L
M
Y
Q
Package
SOT-25
SOT-25
SOT-25
SOT-25
SOT-25
SOT-25
SOT-25
SOT-25
SOT-25
SOT-25
SOT-25
Shipping
3,000 Units/ Tape & Reel
3,000 Units/ Tape & Reel
3,000 Units/ Tape & Reel
3,000 Units/ Tape & Reel
3,000 Units/ Tape & Reel
3,000 Units/ Tape & Reel
3,000 Units/ Tape & Reel
3,000 Units/ Tape & Reel
3,000 Units/ Tape & Reel
3,000 Units/ Tape & Reel
3,000 Units/ Tape & Reel
* For detail Ordering Number identification, please see last page.
PIN DESCRIPTION
Pin Number
1
2
Pin Name
IN
GND
EN
Function
Supply Input
Ground
Enable/ Shutdown(Input): COMS compatible input. Logic high = enable,
logic low or open = shutdown.
Reference Bypass: Connect external 470pF capacitor to GND to reduce
output noise. May be left open.
Regulator Output
GM6155
3
4
5
BYP
OUT
2
GM6155
BLOCK DIAGRAM
V
IN
IN
BYP
OUT
+
+
-
Bandgap
Ref.
V
OUT
C
OUT
C
BYP
(Optional)
EN
Current Limit
Thermal Shutdown
V
IN
GND
IN
OUT
+
ADJ
R1
R2
V
OUT
C
OUT
+
Figure 1. Ultra-Low-Noise Fixed Regulator
-
EN
Current Limit
Thermal Shutdown
Bandgap
Ref.
C
BYP
(Optional)
V
OUT
= V
REF
(1 + R2/ R1)
GND
Figure 2. Ultra-Low-Noise Adjustable Regulator
ABSOLUTE MAXIMUM RATINGS
PARAMETER
Supply Input Voltage
Enable Input Voltage
Power Dissipation (Note 3)
Junction Temperature
Lead Temperature (soldering, 5 seconds)
Storage Temperature
SYMBOL
V
IN
V
EN
P
D
T
J
T
LEAD
T
S
RATINGS
-20 ~ + 20
-20 ~ +20
Internally Limited
-40 ~ +125
260
-60 ~ +150
UNITS
V
V
W
°C
°C
°C
OPERATING RATINGS
Supply Input Voltage
Enable Input Voltage
Junction Temperature
Thermal Resistance
V
IN
V
EN
T
J
q
JA
+2.5 to +16
0 to V
IN
-40 ~ + 125
(Note 3)
V
V
°C
°C/ W
GM6155
3
PARAMETER
SYMBOL
RATINGS
UNITS
GM6155
ELECTRICAL CHARACTERISTICS
(V
IN
= V
OUT
+ 1V; I
L
= 100µA; C
L
= 1.0µF; V
EN
unless otherwise noted)
2.0; T
J
= 25°C,
bold
values indicate -40°C
T
J
+125°C;
Parameter
Output Voltage Accuracy
Output Voltage Temperature
Coefficient
Line Regulation
Load Regulation
Symbol
V
O
DV
O
/
DT
DV
O
/ V
O
DV
O
/ V
O
Test Condition
Variation from specified V
OUT
(Note 4)
V
IN
= V
OUT
+ 1V to 16V
I
L
= 0.1mA to 150mA, (Note 5)
I
L
= 100µA
I
L
= 50mA
Min
-1
-2
Typ
Max
1
2
Unit
%
ppm/ °C
100
0.004
0.02
10
110
140
165
0.01
80
350
600
1300
75
320
0.05
260
500
0.012/
0.05
0.2/
0.5
50
70
150
230
250
300
275
350
1
5
125
150
600
800
1000
1500
1900
2500
%/ V
%/V
Dropout Voltage (Note 6)
V
IN
- V
O
I
L
= 100mA
I
L
= 150mA
mV
Quiescent Current
I
GND
V
EN
0.4V (shutdown)
V
EN
0.18V (shutdown)
V
EN
2.0V, I
L
= 0.1mA
I
L
= 50mA
µA
Ground Pin Current (Note 7)
I
GND
I
L
= 100mA
I
L
= 150mA
µA
Ripple Rejection
Current Limit
Thermal Regulation
Output Noise
ENABLE Input
Enable Input Logic-Low
Voltage
Enable Input Logic-High
Voltage
PSRR
I
LIMT
DV
O
/
DP
D
e
NO
f = 100Hz, I
L
= 0.1mA
V
OUT
= 0V
(Note 8)
I
L
= 50mA, C
L
= 2.2µF,
470pF from BYP to GND
dB
mA
%/ W
nV/ Hz
V
IL
V
IH
I
IL
Regulator shutdown
Regulator enabled
V
IL
V
IL
V
IH
0.4V
0.18V
2.0V
2
5
2.0
0.01
0.4
0.18
V
V
-1
-2
20
25
µA
µA
Enable Input Current
I
IH
GM6155
4
Note 1.
Exceeding the absolute maximum rating may damage the device.
Note 2.
The device is not guaranteed to function outside its operating rating.
Note 3:
The maximum allowable power dissipation at any T
A
(ambient temperature) is P
D
(max) = (T
J
(max) -T
A
)
q
JA
. Exceeding the maximum
allowable power dissipation will result in excessive die temperature, and the regulator will go into thermal shutdown.
Note 4:
Output voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range.
Note 5:
Regulation is measured at constant junction temperature using low duty cycle pulse testing. Parts are tested for load regulation in the
load range from 0.1mA to 150mA. Changes in output voltage due to heating effects are covered by the thermal regulation specification.
Note 6:
Dropout Voltage is defined as the input to output differential at which the output voltage drops 2% below its nominal value measured at
1V differential.
Note 7:
Ground pin current is the regulator quiescent current plus pass transistor base current. The total current drawn from the supply is the
sum of the load current plus the ground pin current.
Note 8:
Thermal regulation is defined as the change in output voltage at a time "t" after a change in power dissipation is applied, excluding load
or line regulation effects. Specifications are for a 150mA load pulse at V
IN
= 16V for t = 10ms.
GM6155
Applications Information
Enable/ Shutdown
Forcing EN (enable/ shutdown) high (>2V) enables the regulator. EN is compatible with CMOS logic gates. If
the enable / shutdown feature is not required, connect EN (pin 3) to IN (supply input, pin 1). See Figure 3.
Input Capacitor
A 1µF capacitor should be placed from IN to GND if there is more than 10 inches of wire between the input
and the acfilter capacitor or if a battery is used as the input .
Reference Bypass Capacitor
BYP (reference bypass) is connected to the internal voltage reference. A 470pF capacitor (C
BYP
) connected
from BYP to GND quiets this reference, providing a significant reduction in output noise. C
BYP
reduces the
regulator phase margin; when using C
BYP
, output capacitors of 2.2µF or greater are generally required to
maintain stability.
The start-up speed of the GM6155 is inversely proportional to the size of the reference bypass capacitor.
Applications requiring a slow ramp-up of output voltage should consider larger values of C
BYP
. Likewise, if
rapid turn-on is necessary, consider omitting C
BYP
.
If output noise is not a major concern, omit C
BYP
and leave BYP open.
Output Capacitor
An output capacitor required between OUT and GND to prevent oscillation. The minimum size of the output
capacitor is dependent upon whether a reference bypass capacitor is used. 1.0µF minimum is recommended
when C
BYP
is not used (see Figure 2). 2.2µF minimum is recommended when C
BYP
is 470pF (see Figure 1).
Larger values improve the regulator's transient response. The output capacitor value may be increased
without limit.
The output capacitor is should have an ESR (effective series resistance) of about 5W or less and a resonant
frequency above 1MHz. Ultra-low-ESR capacitors can cause a low amplitude oscillation on the output and/
or underdamped transient response. Most tantalum or aluminum electrolytic capacitors are adequate; film
types will work, but are more expensive. Since many aluminum electrolytics have electrolytes that freeze at
about -30°C, solid tantalums ate recommended for operation below -25°C.
At lower values for output current, less output capacitance is required for output stability. The capacitor can
be reduced to 0.47µF for current below 10mA or 0.33µF for current below 1mA.
No-Load Stability
The GM6155 will remain stable and in regulation with no load (other than the internal voltage divider) unlike
many other voltage regulators. This is especially important in CMOS RAM keep-alive applications.
Thermal Considerations
The GM6155 is designed to provide 150mA of continuous current in a very small package. Maximum power
dissipation can be calculated based on the output current and the voltage drop across the part. To determine
the maximum power dissipation of the package, use the junction-to-ambient thermal resistance of the device
and the following basic equation:
P
D(max)
=
R
q
JA
T
J(max)
is the maximum junction temperature of the die, 125°C, and T
A
is the ambient operating temperature.
R
qJA
is layout dependent; Table 1 shows examples of junction-to-ambient thermal resistance for the GM6155.
GM6155
5
(T
J(max)
- T
A
)
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