LTC3025
300mA Micropower
VLDO Linear Regulator
FEATURES
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DESCRIPTION
The LTC
®
3025 is a micropower, VLDO
TM
(very low drop-
out) linear regulator which operates from input voltages as
low as 0.9V. The device is capable of supplying 300mA of
output current with a typical dropout voltage of only 45mV.
A BIAS supply is required to run the internal reference and
LDO circuitry while output current comes directly from
the IN supply for high efficiency regulation. The low 0.4V
internal reference voltage allows the LTC3025 output to
be programmed to much lower voltages than available in
common LDOs (range of 0.4V to 3.6V). The output voltage
is programmed via two ultrasmall SMD resistors.
The LTC3025’s low quiescent current makes it an ideal
choice for use in battery-powered systems. For 3-cell
NiMH and single cell Li-Ion applications, the BIAS voltage
can be supplied directly from the battery while the input
can come from a high efficiency buck regulator, providing
a high efficiency, low noise output.
Other features include high output voltage accuracy,
excellent transient response, stability with ultralow ESR
ceramic capacitors as small as 1μF short-circuit and
,
thermal overload protection and output current limiting.
The LTC3025 is available in a tiny, low profile (0.75mm)
6-lead DFN (2mm
×
2mm) package.
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and VLDO
and ThinSOT are trademarks of Linear Technology Corporation. All other trademarks are the
property of their respective owners.
Wide Input Voltage Range: 0.9V to 5.5V
Stable with Ceramic Capacitors
Very Low Dropout: 45mV at 300mA
Adjustable Output Range: 0.4V to 3.6V
±2%
Voltage Accuracy over Temperature
Supply Load
Low Noise: 80μV
RMS
(10Hz to 100kHz)
BIAS Voltage Range: 2.5V to 5.5V
Fast Transient Recovery
Shutdown Disconnects Load from V
IN
and V
BIAS
Low Operating Current: I
IN
= 4μA, I
BIAS
= 50μA Typ
Low Shutdown Current: I
IN
= 1μA, I
BIAS
= 0.01μA Typ
Output Current Limit
Thermal Overload Protection
Available in 6-Lead (2mm
×
2mm) DFN Package
APPLICATIONS
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Low Power Handheld Devices
Low Voltage Logic Supplies
DSP Power Supplies
Cellular Phones
Portable Electronic Equipment
Handheld Medical Instruments
Post Regulator for Switching Supply Noise Rejection
TYPICAL APPLICATION
1.2V Output Voltage from 1.5V Input Supply
50
BIAS
Li-Ion
OR
3-CELL
NiMH
1.5V HIGH
EFFICIENCY 1.5V
DC/DC
BUCK
0.1μF
IN
0.1μF
OFF ON
SHDN
GND
3025 TA01
1MHz V
IN
Supply Rejection
1μF
V
OUT
= 1.2V
I
OUT
≤ 300mA
45
40
REJECTION (dB)
35
30
25
20
15
10
5 BIAS = 3.6V
V
OUT
= 1.2V
0
1.2 1.4 1.6
I
OUT
= 100mA
I
OUT
= 300mA
1.8 2.0
V
IN
(V)
2.2
2.4
2.6
3025fd
OUT
LTC3025
ADJ
40.2k
80.6k
C
OUT
= 10μF
C
OUT
= 1μF
3025 TA01b
1
LTC3025
ABSOLUTE MAXIMUM RATINGS
(Notes 1, 2)
PIN CONFIGURATION
TOP VIEW
BIAS 1
GND 2
IN 3
7
6 SHDN
5 ADJ
4 OUT
V
BIAS
, V
IN
to GND......................................... –0.3V to 6V
SHDN
to GND............................................... –0.3V to 6V
ADJ to GND.................................................. –0.3V to 6V
V
OUT
........................................–0.3V to V
IN
+ 0.3V or 6V
Operating Junction Temperature Range
(Note 3).................................................. –40°C to 125°C
Storage Temperature Range................... –65°C to 125°C
Output Short-Circuit Duration .......................... Indefinite
DC6 PACKAGE
6-LEAD (2mm 2mm) PLASTIC DFN
T
JMAX
= 125°C,
θ
JA
= 102°C/W,
θ
JC
= 20°C/W
EXPOSED PAD (PIN 7) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
LTC3025EDC#PBF
LTC3025IDC#PBF
LEAD BASED FINISH
LTC3025EDC
LTC3025IDC
TAPE AND REEL
LTC3025EDC#TRPBF
LTC3025IDC#TRPBF
TAPE AND REEL
LTC3025EDC#TR
LTC3025IDC#TR
PART MARKING*
LBDY
LBDY
PART MARKING*
LBDY
LBDY
PACKAGE DESCRIPTION
6-Lead (2mm
×
2mm) Plastic DFN
6-Lead (2mm
×
2mm) Plastic DFN
PACKAGE DESCRIPTION
6-Lead (2mm
×
2mm) Plastic DFN
6-Lead (2mm
×
2mm) Plastic DFN
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 1.5V, V
BIAS
= 3.6V, V
OUT
= 1.2V, C
OUT
= 1μF C
IN
= 0.1μF
,
,
C
BIAS
= 0.1μF (all capacitors ceramic) unless otherwise noted. (Note 3)
PARAMETER
V
IN
Operating Voltage (Note 4)
V
BIAS
Operating Voltage (Note 4)
V
BIAS
Undervoltage Lockout
V
IN
Operating Current
V
BIAS
Operating Current
V
IN
Shutdown Current
V
BIAS
Shutdown Current
V
ADJ
Regulation Voltage (Note 5)
I
ADJ
ADJ Input Current
OUT Load Regulation (Referred to ADJ Pin)
V
IN
Line Regulation (Referred to ADJ Pin)
BIAS Line Regulation (Referred to ADJ Pin)
I
OUT
= 10μA
I
OUT
= 10μA
V
SHDN
= 0V
V
SHDN
= 0V
1mA ≤ I
OUT
≤ 300mA, 1.5V ≤ V
IN
≤ 5V
1mA ≤ I
OUT
≤ 300mA, 1.5V ≤ V
IN
≤ 5V
V
ADJ
= 0.45V
∆I
OUT
= 1mA to 300mA
V
IN
= 1.5V to 5V, V
BIAS
= 3.6V, V
OUT
= 1.2V,
I
OUT
= 1mA
V
IN
= 1.5V, V
BIAS
= 2.6V to 5V, V
OUT
= 1.2V
I
OUT
= 1mA
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ELECTRICAL CHARACTERISTICS
CONDITIONS
MIN
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TYP
MAX
5.5
5.5
UNITS
V
V
V
μA
μA
μA
μA
V
V
nA
mV
mV
0.9
2.5
2.2
4
50
1
0.01
0.395
0.392
–50
0.4
0.4
0
–0.2
0.07
1.7
2.5
10
80
5
1
0.405
0.408
50
5.5
mV
3025fd
2
LTC3025
ELECTRICAL CHARACTERISTICS
PARAMETER
V
IN
to V
OUT
Dropout Voltage (Notes 4, 6, 7)
V
BIAS
to V
OUT
Dropout Voltage (Note 4)
I
OUT
Continuous Output Current
I
OUT
Current Limit
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Output Voltage Noise
V
IH
SHDN
Input High Voltage
V
IL
SHDN
Input Low Voltage
I
IH
SHDN
Input High Current
I
L
SHDN
Input Low Current
SHDN
= 1.2V
SHDN
= 0V
V
ADJ
= 0V
f = 10Hz to 100kHz, I
OUT
= 300mA
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The
l
denotes the specifications which apply over the full operating
,
,
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 1.5V, V
BIAS
= 3.6V, V
OUT
= 1.2V, C
OUT
= 1μF C
IN
= 0.1μF
C
BIAS
= 0.1μF (all capacitors ceramic) unless otherwise noted. (Note 3)
CONDITIONS
V
BIAS
= 2.8V, V
IN
= 1.5V, V
ADJ
= 0.37V, I
OUT
= 300mA
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MIN
TYP
45
MAX
100
1.4
UNITS
mV
V
mA
mA
μV
RMS
V
300
680
80
0.9
0.3
–1
–1
1
1
V
μA
μA
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2:
This IC includes overtemperature protection that is intended
to protect the device during momentary overload conditions. Junction
temperature will exceed 125°C when overtemperature protection is active.
Continuous operation above the specified maximum operating junction
temperature may impair device reliability.
Note 3:
The LTC3025 regulator is tested and specified under pulse
load conditions such that T
J
≈ T
A
. The LTC3025 is 100% production
tested at 25°C. Performance at –40°C and 125°C is assured by design,
characterization and correlation with statistical process control. The
LTC3025I is guaranteed to meet performance specifications over the full
–40°C and 125°C operating junction temperature range.
Note 4:
For the LTC3025, a regulated output voltage will only be available
when the minimum IN and BIAS Operating Voltages as well as the IN to
OUT and BIAS to OUT Dropout Voltages are all satisfied.
Note 5:
Operating conditions are limited by maximum junction
temperature. The regulated output voltage specification will not apply
for all possible combinations of input voltage and output current. When
operating at maximum input voltage, the output current range must be
limited. When operating at maximum output current, the input voltage
range must be limited.
Note 6:
Dropout voltage is minimum input to output voltage differential
needed to maintain regulation at a specified output current. In dropout, the
output voltage will be equal to V
IN
– V
DROPOUT
.
Note 7:
The DFN output FET on-resistance in dropout is guaranteed by
correlation to wafer level measurements.
TYPICAL PERFORMANCE CHARACTERISTICS
Dropout Voltage vs I
OUT
70
60
DROPOUT VOLTAGE (mV)
50
40
30
20
10
0
0
50
100
T
A
= –40°C
T
A
= 125°C
I
BIAS
(μA)
T
A
= 25°C
V
BIAS
= 2.8V
400
350
300
I
BIAS
(μA)
250
125°C
200
25°C
150
–40°C
100
50
200
150
I
OUT
(mA)
250
300
3025 G01
Operating BIAS Current
vs Output Load
80
BIAS No Load Operating Current
V
IN
= 1.5V
70 V
OUT
= 1.2V
60
50
40
30
20
10
125°C
–40°C
25°C
0
0.01
0.1
1
10
I
OUT
(mA)
100
1000
3025 G02
0
2.5
3
3.5
4
V
BIAS
(V)
4.5
5
5.5
3025 G03
3025fd
3
LTC3025
TYPICAL PERFORMANCE CHARACTERISTICS
V
IN
No Load Operating Current
14
12
10
I
IN
(μA)
8
6
4
2
0
0.5
V
BIAS
= 5V
V
OUT
= 0.8V
7
6
125°C
85°C
25°C
–40°C
2
85°C
1
0
0.5
I
IN
(μA)
5
4
3
25°C
–40°C
ADJUST VOLTAGE (mV)
V
IN
Shutdown Current
V
BIAS
= 5V
405
404
403
402
401
400
399
398
397
396
1.5
2.5
3.5
4.5
5.5
3025 G05
Adjust Voltage vs Temperature
V
BIAS
= 3.6V
V
IN
= 1.5V
I
OUT
= 10μA
1.5
2.5
3.5
4.5
5.5
3025 G04
395
–50
–25
V
IN
(V)
V
IN
(V)
50
25
0
75
TEMPERATURE (°C)
100
125
3025 G06
SHDN
Threshold vs Temperature
1000
900
800
SHDN THRESHOLD (mV)
700
600
500
400
300
200
100
0
–50
–25
50
25
0
75
TEMPERATURE (°C)
100
125
V
BIAS
= 2.5V
V
BIAS
= 5V
CURRENT LIMIT (mA)
1200
1000
800
600
400
200
0
1600
Current Limit vs V
IN
Voltage
V
BIAS
= 3.6V
V
OUT
= 0V
1400
V
IN
AC
100mV/DIV
Burst Mode DC/DC Buck Ripple
Rejection
V
OUT
AC
10mV/DIV
0
1
2
3
V
IN
(V)
4
5
6
3025 G08
V
IN
= 1.8V
V
OUT
= 1.5V
C
OUT
= 1μF
I
OUT
= 50mA
10μs/DIV
3025 G09
3025 G07
V
IN
Ripple Rejection
vs Frequency
70
60
50
40
C
OUT
= 1μF
30
20
10
C
OUT
= 10μF
REJECTION (dB)
70
60
50
40
30
BIAS Ripple Rejection
vs Frequency
C
OUT
= 10μF
REJECTION (dB)
C
OUT
= 1μF
20
10
V
BIAS
= 3.6V
V
IN
= 1.5V
V
OUT
= 1.2V
I
OUT
= 100mA
1k
10k
100k
1M
10M
3025 G11
0
100
V
BIAS
= 3.6V
V
IN
= 1.5V
V
OUT
= 1.2V
I
OUT
= 100mA
1k
10k
100k
1M
10M
3025 G10
0
100
FREQUENCY (Hz)
FREQUENCY (Hz)
3025fd
4
LTC3025
TYPICAL PERFORMANCE CHARACTERISTICS
3MHz V
IN
Supply Rejection
50
45
40
REJECTION (dB)
35
30
25
20
15
10
5 V
BIAS
= 3.6V
V
OUT
= 1.2V
0
1.2 1.4 1.6
I
OUT
= 100mA
I
OUT
= 300mA
1.8 2.0
V
IN
(V)
2.2
2.4
2.6
V
IN
= 1.5V
V
OUT
= 1.2V
V
BIAS
= 3.6V
C
OUT
= 1μF
100μs/DIV
V
OUT
AC
10mV/DIV
C
OUT
= 10μF
C
OUT
= 1μF
250mA
I
OUT
10mA
Transient Response
3025 G13
3025 G12
PIN FUNCTIONS
BIAS (Pin 1):
BIAS Input Voltage. BIAS provides internal
power for LTC3025 circuitry. The BIAS pin should be lo-
cally bypassed to ground if the LTC3025 is more than a
few inches away from another source of bulk capacitance.
In general, the output impedance of a battery rises with
frequency, so it is usually advisable to include an input
bypass capacitor in battery-powered circuits. A capacitor
in the range of 0.01μF to 0.1μF is usually sufficient.
GND (Pin 2):
Ground. Connect to a ground plane.
IN (Pin 3):
Input Supply Voltage. The output load current
is supplied directly from IN. The IN pin should be locally
bypassed to ground if the LTC3025 is more than a few inches
away from another source of bulk capacitance. In general,
the output impedance of a battery rises with frequency, so
it is usually advisable to include an input bypass capacitor
when supplying IN from a battery. A capacitor in the range
of 0.1μF to 1μF is usually sufficient.
OUT (Pin 4):
Regulated Output Voltage. The OUT pin
supplies power to the load. A minimum ceramic output
capacitor of at least 1μF is required to ensure stability.
Larger output capacitors may be required for applications
with large transient loads to limit peak voltage transients.
See the Applications Information section for more informa-
tion on output capacitance.
ADJ (Pin 5):
Adjust Input. This is the input to the error
amplifier. The ADJ pin reference voltage is 0.4V referenced
to ground. The output voltage range is 0.4V to 3.6V and is
typically set by connecting ADJ to a resistor divider from
OUT to GND. See Figure 2.
SHDN
(Pin 6):
Shutdown Input, Active Low. This pin is
used to put the LTC3025 into shutdown. The
SHDN
pin
current is typically less than 10nA. The
SHDN
pin cannot
be left floating and must be tied to a valid logic level (such
as BIAS) if not used.
GND (Exposed Pad Pin 7):
Ground and Heat Sink. Must
be soldered to PCB ground plane or large pad for optimal
thermal performance.
3025fd
5
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