LTC3410-1.875
2.25MHz, 300mA
Synchronous Step-Down
Regulator in SC70
FEATURES
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DESCRIPTIO
High Efficiency: Up to 93%
Very Low Quiescent Current: Only 26
µ
A
Low Output Voltage Ripple
300mA Output Current at V
IN
= 3V
380mA Minimum Peak Switch Current
2.5V to 5.5V Input Voltage Range
2.25MHz Constant Frequency Operation
No Schottky Diode Required
Stable with Ceramic Capacitors
Shutdown Mode Draws < 1µA Supply Current
±2%
Output Voltage Accuracy
Current Mode Operation for Excellent Line and
Load Transient Response
Overtemperature Protected
Available in Low Profile SC70 Package
The LTC
®
3410-1.875 is a high efficiency monolithic syn-
chronous buck regulator using a constant frequency,
current mode architecture. Supply current during opera-
tion is only 26µA, dropping to <1µA in shutdown. The 2.5V
to 5.5V input voltage range makes the LTC3410-1.875
ideally suited for single Li-Ion battery-powered applica-
tions. 100% duty cycle provides low dropout operation,
extending battery life in portable systems.
Switching frequency is internally set at 2.25MHz, allowing
the use of small surface mount inductors and capacitors.
The LTC3410-1.875 is specifically designed to work well
with ceramic output capacitors, achieving very low output
voltage ripple and a small PCB footprint.
The internal synchronous switch increases efficiency and
eliminates the need for an external Schottky diode. The
LTC3410-1.875 is available in a tiny, low profile SC70
package.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners. Protected by U.S. Patents,
including 5481178, 5994885, 6127815, 6304066, 6498466, 6580258, 6611131.
APPLICATIO S
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Cellular Telephones
Wireless and DSL Modems
Digital Cameras
MP3 Players
Portable Instruments
TYPICAL APPLICATIO
V
IN
2.7V
TO 5.5V
V
IN
RUN
V
OUT
GND
SW
Efficiency and Power Loss vs
Output Current
100
90
V
OUT
1.875V
4.7µH
C
IN
4.7µF
CER
LTC3410-1.875
C
OUT
4.7µF
CER
EFFICIENCY
V
IN
80
70
EFFICIENCY (%)
60
50
40
30
34101875 TA01
20
10
4.2V
0
0.1
U
2.7V
1
4.2V
3.6V
3.6V
0.01
2.7V
POWER LOSS
V
IN
0.001
0.1
U
U
POWER LOSS (W)
1
10
100
OUTPUT CURRENT (mA)
0.0001
1000
34101875 TA02
34101875f
1
LTC3410-1.875
ABSOLUTE
(Note 1)
AXI U
RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
RUN 1
GND 2
SW 3
6 V
OUT
5 GND
4 V
IN
Input Supply Voltage .................................. – 0.3V to 6V
RUN, V
OUT
Voltages................................... – 0.3V to V
IN
SW Voltage (DC) ......................... – 0.3V to (V
IN
+ 0.3V)
P-Channel Switch Source Current (DC) ............. 500mA
N-Channel Switch Sink Current (DC) ................. 500mA
Peak SW Sink and Source Current .................... 630mA
Operating Temperature Range (Note 2) .. – 40°C to 85°C
Junction Temperature (Notes 3, 5) ...................... 125°C
Storage Temperature Range ................ – 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
ORDER PART
NUMBER
LTC3410ESC6-1.875
SC6 PART MARKING
LCFQ
SC6 PACKAGE
6-LEAD PLASTIC SC70
T
JMAX
= 125°C,
θ
JA
= 250°C/ W
Order Options
Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking:
http://www.linear.com/leadfree/
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
The
●
denotes specifications which apply over the full operating temperature range, otherwise specifications are T
A
= 25°C.
V
IN
= 3.6V unless otherwise specified.
SYMBOL
I
VOUT
I
PK
V
OUT
∆V
OUT
V
LOADREG
V
IN
V
UVLO
I
S
PARAMETER
Output Voltage Feedback Current
Peak Inductor Current
Regulated Output Voltage
Output Voltage Line Regulation
Output Voltage Load Regulation
Input Voltage Range
Undervoltage Lockout Threshold
Input DC Bias Current
Burst Mode
®
Operation
Shutdown
Oscillator Frequency
R
DS(ON)
of P-Channel FET
R
DS(ON)
of N-Channel FET
SW Leakage
RUN Threshold
RUN Leakage Current
V
IN
Rising
V
IN
Falling
(Note 4)
V
OUT
= 1.945V, I
LOAD
= 0A
V
RUN
= 0V
V
OUT
= 1.875V
V
OUT
= 0V
I
SW
= 100mA
I
SW
= –100mA
V
RUN
= 0V, V
SW
= 0V or 5V, V
IN
= 5V
●
●
●
CONDITIONS
●
MIN
380
●
TYP
3.3
500
1.875
0.04
0.5
MAX
6
1.913
0.4
5.5
UNITS
µA
mA
V
%/V
%
V
V
V
µA
µA
MHz
kHz
Ω
Ω
µA
V
µA
V
IN
= 3V, V
OUT
= 1.64V, Duty Cycle < 35%
V
IN
= 2.5V to 5.5V
I
LOAD
= 50mA to 250mA
●
●
1.837
2.5
2
1.94
26
0.1
1.8
2.25
310
0.75
0.55
±0.01
0.3
1
±0.01
2.3
35
1
2.7
0.9
0.7
±1
1.5
±1
f
OSC
R
PFET
R
NFET
I
LSW
V
RUN
I
RUN
Burst Mode is a registered trademark of Linear Technology Corporation.
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:
The LTC3410E-1.875 is guaranteed to meet performance
specifications from 0°C to 70°C. Specifications over the –40°C to 85°C
operating temperature range are assured by design, characterization and
correlation with statistical process controls.
Note 3:
T
J
is calculated from the ambient temperature T
A
and power
dissipation P
D
according to the following formula:
LTC3410-1.875: T
J
= T
A
+ (P
D
)(250°C/W)
Note 4:
Dynamic supply current is higher due to the gate charge being
delivered at the switching frequency.
Note 5:
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.
34101875f
2
U
W
U
U
W W
W
LTC3410-1.875
TYPICAL PERFOR A CE CHARACTERISTICS
(From Figure 1)
Efficiency vs Input Voltage
100
90
80
I
OUT
= 250mA
70
60
50
40
30
2.5
I
OUT
= 0.1mA
I
OUT
= 100mA
EFFFICIENCY (%)
I
OUT
= 1mA
EFFICIENCY (%)
3
4.5
4
3.5
INPUT VOLTAGE (V)
Output Voltage
vs Temperature
1.911
V
IN
= 3.6V
2.7
2.6
OSCILLATOR FREQUENCY (MHz)
1.899
OUTPUT VOLTAGE (V)
1.887
1.875
1.863
1.851
1.839
–50 –25
50
25
75
0
TEMPERATURE (°C)
Oscillator Frequency
vs Supply Voltage
2.7
2.6
OSCILLATOR FREQUENCY (MHz)
OUTPUT VOLTAGE (V)
2.5
2.4
2.3
2.2
2.1
2.0
1.9
1.8
2
3
5
4
SUPPLY VOLTAGE (V)
6
34101875 G05
U W
Efficiency vs Output Current
100
90
80
I
OUT
= 10mA
70
60
50
40
30
20
10
V
IN
= 2.7V
V
IN
= 3.6V
V
IN
= 4.2V
1
10
100
OUTPUT CURRENT (mA)
1000
34101875 G02
5
5.5
0
0.1
34101875 G01
Oscillator Frequency
vs Temperature
V
IN
= 3.6V
2.5
2.4
2.3
2.2
2.1
2.0
1.9
100
125
1.8
–50
–25
0
25
50
75
TEMPERATURE (°C)
100
125
34101875 G03
34101875 G04
Output Voltage vs Load Current
1.900
1.895
1.890
1.885
1.880
1.875
1.870
1.865
1.860
1.855
1.850
0
200
100
300
LOAD CURRENT (mA)
400
34101875 G06
34101875f
3
LTC3410-1.875
TYPICAL PERFOR A CE CHARACTERISTICS
(From Figure 1)
R
DS(ON
) vs Input Voltage
1.2
1.1
1.0
0.9
R
DS (ON)
(Ω)
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
1
2
R
DS (ON)
(Ω)
SYNCHRONOUS SWITCH
5
4
3
INPUT VOLTAGE (V)
Dynamic Supply Current vs V
IN
50
I
LOAD =
0A
DYNAMIC SUPPLY CURRENT (µA)
40
DYNAMIC SUPPLY CURRENT (µA)
30
20
10
0
1
2
Switch Leakage vs Temperature
110
100
90
SWITCH LEAKAGE (nA)
V
IN
= 5.5V
RUN = 0V
80
70
60
50
40
30
20
10
0
–50
–25
50
25
0
75
TEMPERATURE (°C)
100
125
MAIN
SWITCH
SYNCHRONOUS
SWITCH
LEAKAGE CURRENT (pA)
4
U W
3
V
IN
(V)
R
DS(ON)
vs Temperature
1.2
1.0
V
IN
= 4.2V
V
IN
= 2.7V
V
IN
= 3.6V
MAIN SWITCH
0.8
0.6
V
IN
= 4.2V
0.4
V
IN
= 2.7V
0.2
V
IN
= 3.6V
MAIN SWITCH
SYNCHRONOUS SWITCH
6
7
0
–50 –30 –10 10 30 50 70 90 110 130
TEMPERATURE (°C)
34101875 G08
34101875 G07
Dynamic Supply Current
vs Temperature
50
40
30
20
10
4
5
6
34101875 G09
0
–50 –25
50
25
0
75
TEMPERATURE (°C)
100
125
34101875 G10
Switch Leakage vs Input Voltage
600
550
500
450
400
350
300
250
200
150
100
50
0
0
1
4
3
2
INPUT VOLTAGE (V)
5
6
SYNCHRONOUS
SWITCH
MAIN
SWITCH
34101875 G11
34101875 G12
34101875f
LTC3410-1.875
TYPICAL PERFOR A CE CHARACTERISTICS
(From Figure 1)
Burst Mode Operation
Start-Up from Shutdown
SW
5V/DIV
V
OUT
50mV/DIV
AC COUPLED
I
L
100mA/DIV
2µs/DIV
V
IN
= 3.6V
I
LOAD
= 10mA
Start-Up from Shutdown
RUN
2V/DIV
V
OUT
1V/DIV
I
L
200mA/DIV
V
IN
= 3.6V
I
LOAD
= 0A
200µs/DIV
34101875 G15
U W
RUN
2V/DIV
V
OUT
1V/DIV
I
L
200mA/DIV
200µs/DIV
34101875 G13
V
IN
= 3.6V
I
LOAD
= 300mA
34101875 G14
Load Step
V
OUT
100mV/DIV
AC-COUPLED
I
L
200mA/DIV
I
LOAD
200mA/DIV
10µs/DIV
V
IN
= 3.6V
I
LOAD
= 0mA TO 300mA
34101875 G16
Load Step
V
OUT
100mV/DIV
AC-COUPLED
I
L
200mA/DIV
I
LOAD
200mA/DIV
10µs/DIV
V
IN
= 3.6V
I
LOAD
= 15mA TO 300mA
34101875 G17
34101875f
5
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