LTC3410B
2.25MHz, 300mA
Synchronous Step-Down
Regulator in SC70
FEATURES
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DESCRIPTIO
High Efficiency: Up to 96%
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
Low Dropout Operation: 100% Duty Cycle
Stable with Ceramic Capacitors
0.8V Reference Allows Low Output Voltages
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
®
3410B is a high efficiency monolithic synchro-
nous buck regulator using a constant frequency, current
mode architecture. The device is available in adjustable
and fixed output voltage versions. Supply current during
operation is only 200µA, dropping to <1µA in shutdown.
The 2.5V to 5.5V input voltage range makes the LTC3410B
ideally suited for single Li-Ion battery-powered applica-
tions. 100% duty cycle provides low dropout operation,
extending battery life in portable systems. PWM pulse
skipping mode operation provides very low output ripple
voltage for noise sensitive applications.
Switching frequency is internally set at 2.25MHz, allowing
the use of small surface mount inductors and capacitors.
The LTC3410B 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. Low
output voltages are easily supported with the 0.8V feed-
back reference voltage. The LTC3410B 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, 6580258, 6304066, 6127815, 6498466, 6611131.
APPLICATIO S
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Cellular Telephones
Personal Information Appliances
Wireless and DSL Modems
Digital Still Cameras
MP3 Players
Portable Instruments
TYPICAL APPLICATIO
V
IN
2.7V
TO 5.5V
V
IN
RUN
V
FB
GND
SW
Efficiency and Power Loss
vs Output Current
100
90
1
EFFICIENCY
0.1
4.7µH
C
IN
2.2µF
CER
LTC3410B
10pF
C
OUT
2.2µF
CER
V
OUT
1.2V
EFFICIENCY (%)
80
70
60
50
40
30
20
20
0
1
232k
464k
3410 TA01
U
POWER LOSS (W)
POWER LOSS
0.01
0.001
V
IN
= 2.7V
V
IN
= 3.6V
V
IN
= 4.2V
10
100
OUTPUT CURRENT (mA)
0.0001
1000
3410 TA01b
U
U
3410bfa
1
LTC3410B
ABSOLUTE
AXI U
RATI GS
Input Supply Voltage .................................. – 0.3V to 6V
RUN, V
FB
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
PACKAGE/ORDER I FOR ATIO
TOP VIEW
RUN 1
GND 2
SW 3
6 V
FB
5 GND
4 V
IN
SC6 PACKAGE
6-LEAD PLASTIC SC70
T
JMAX
= 125°C,
θ
JA
= 250°C/ W
ORDER PART NUMBER
LTC3410BESC6
SC6 PART MARKING
LBZY
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
VFB
I
VOUT
I
PK
V
FB
∆V
FB
V
OUT
PARAMETER
Feedback Current
Output Voltage Feedback Current
Peak Inductor Current
Regulated Feedback Voltage
Reference Voltage Line Regulation
Regulated Output Voltage
CONDITIONS
Adjustable Output Voltage
Fixed Output Voltage
V
IN
= 3V, V
FB
= 0.7V or V
OUT
= 90%, Duty Cycle < 35%
Adjustable Output Voltage (LTC3410BE)
V
IN
= 2.5V to 5.5V
LTC3410B-1.2, I
OUT
= 100mA
LTC3410B-1.5, I
OUT
= 100mA
LTC3410B-1.8, I
OUT
= 100mA
LTC3410B-1.875, I
OUT
= 100mA
V
IN
= 2.5V to 5.5V
I
LOAD
= 50mA to 250mA
●
●
●
●
●
●
●
●
●
●
∆V
OUT
V
LOADREG
V
IN
V
UVLO
Output Voltage Line Regulation
Output Voltage Load Regulation
Input Voltage Range
Undervoltage Lockout Threshold
V
IN
Rising
V
IN
Falling
2
U
U
W
W W
U
W
(Note 1)
Peak SW Sink and Source Current .................... 630mA
Operating Temperature Range (Note 2) .. – 40°C to 85°C
Junction Temperature (Note 3) ............................ 125°C
Storage Temperature Range ................ – 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
TOP VIEW
RUN 1
GND 2
SW 3
6 V
OUT
5 GND
4 V
IN
SC6 PACKAGE
6-LEAD PLASTIC SC70
T
JMAX
= 125°C,
θ
JA
= 250°C/ W
ORDER PART NUMBER
LTC3410BESC6-1.2
LTC3410BESC6-1.5
LTC3410BESC6-1.8
LTC3410BESC6-1.875
SC6 PART MARKING
LCMX
LCMY
LCMZ
LCHZ
MIN
TYP
3.3
MAX
±30
6
600
0.816
0.4
1.224
1.53
1.836
1.913
0.4
5.5
UNITS
nA
µA
mA
V
%/V
V
V
V
V
%/V
%
V
V
V
3410bfa
380
0.784
1.176
1.47
1.764
1.837
490
0.8
0.04
1.2
1.5
1.8
1.875
0.04
0.5
2.5
2.0
1.94
2.3
LTC3410B
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
S
PARAMETER
Input DC Bias Current
Operating
Shutdown
Oscillator Frequency
R
DS(ON)
of P-Channel FET
R
DS(ON)
of N-Channel FET
SW Leakage
RUN Threshold
RUN Leakage Current
CONDITIONS
(Note 4)
V
FB
= 0.83V or V
OUT
= 104%, I
LOAD
= 0A
V
RUN
= 0V
V
FB
= 0.8V or V
OUT
= 100%
V
FB
= 0V or V
OUT
= 0V
I
SW
= 100mA
I
SW
= –100mA
V
RUN
= 0V, V
SW
= 0V or 5V, V
IN
= 5V
●
●
●
MIN
TYP
200
0.1
MAX
300
1
2.7
0.9
0.7
±1
1.5
±1
UNITS
µA
µA
MHz
kHz
Ω
Ω
µA
V
µA
f
OSC
R
PFET
R
NFET
I
LSW
V
RUN
I
RUN
1.8
2.25
310
0.75
0.55
±0.01
0.3
1
±0.01
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 LTC3410BE is guaranteed to meet performance specifications
from 0°C to 85°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:
LTC3410B: 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.
TYPICAL PERFOR A CE CHARACTERISTICS
(From Figure 1 Except for the Resistive Divider Resistor Values)
Efficiency vs Input Voltage
100
90
I
OUT
= 100mA
80
EFFICIENCY (%)
100
90
70
I
OUT
= 10mA
60
I
OUT
= 1mA
50
40
30
20
2.5
V
OUT
= 1.2V
3
4.5
4
INPUT VOLTAGE (V)
3.5
5
5.5
3410 G01
EFFICIENCY (%)
I
OUT
= 250mA
70
60
50
40
30
20
10
0
V
OUT
= 1.8V
1
10
100
OUTPUT CURRENT (mA)
V
IN
= 2.7V
V
IN
= 3.6V
V
IN
= 4.2V
1000
3410 G02
REFERENCE VOLTAGE (V)
U W
Efficiency vs Output Current
0.814
Reference Voltage vs
Temperature
V
IN
= 3.6V
0.809
0.804
0.799
0.794
0.789
0.784
–50 –25
80
50
25
75
0
TEMPERATURE (°C)
100
125
3410 G03
3410bfa
3
LTC3410B
TYPICAL PERFOR A CE CHARACTERISTICS
(From Figure 1 Except for the Resistive Divider Resistor Values)
Oscillator Frequency vs
Temperature
2.7
2.6
V
IN
= 3.6V
2.7
2.6
OSCILLATOR FREQUENCY (MHz)
OSCILLATOR FREQUENCY (MHz)
2.5
2.4
2.3
2.2
2.1
2.0
1.9
2.4
2.3
2.2
2.1
2.0
1.9
1.8
V
OUT
ERROR (%)
1.8
–50
–25
0
25
50
75
TEMPERATURE (°C)
R
DS(ON
) vs Input Voltage
1.2
1.1
1.0
0.9
R
DS (ON)
(Ω)
1.0
MAIN SWITCH
R
DS (ON)
(Ω)
V
IN
= 3.6V
DYNAMIC SUPPLY CURRENT (µA)
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
1
2
SYNCHRONOUS SWITCH
5
4
3
INPUT VOLTAGE (V)
Dynamic Supply Current
vs Temperature
250
110
V
OUT
= 1.2V
I
LOAD =
0A
230
SWITCH LEAKAGE (nA)
DYNAMIC SUPPLY CURRENT (µA)
210
190
170
150
–50
–25
4
U W
100
3410 G04
Oscillator Frequency vs
Supply Voltage
1.0
0.6
0.2
–0.2
–0.6
–1.0
–1.4
–1.8
–2.2
–2.6
–3.0
2
3
5
4
SUPPLY VOLTAGE (V)
6
3410 G05
Output Voltage vs Load Current
V
IN
= 3.6V
V
OUT
= 1.8V
2.5
125
0
100
300
400
200
LOAD CURRENT (mA)
500
3410 G06
R
DS(ON)
vs Temperature
1.2
V
IN
= 4.2V
V
IN
= 2.7V
0.8
0.6
V
IN
= 4.2V
0.4
V
IN
= 2.7V
0.2
V
IN
= 3.6V
MAIN SWITCH
SYNCHRONOUS SWITCH
300
Dynamic Supply Current vs V
IN
V
OUT
= 1.2V
I
LOAD =
0A
260
220
180
140
6
7
3410 G07
0
–50 –30 –10 10 30 50 70 90 110 130
TEMPERATURE (°C)
3410 G08
100
1
2
3
V
IN
(V)
4
5
6
3410 G09
Switch Leakage vs Temperature
100
90
80
70
60
50
40
30
20
10
0
–50
MAIN
SWITCH
SYNCHRONOUS
SWITCH
V
IN
= 5.5V
RUN = 0V
50
25
0
75
TEMPERATURE (°C)
100
125
–25
50
25
0
75
TEMPERATURE (°C)
100
125
3410 G10
3410 G11
3410bfa
LTC3410B
TYPICAL PERFOR A CE CHARACTERISTICS
(From Figure 1 Except for the Resistive Divider Resistor Values)
Switch Leakage vs Input Voltage
600
550
500
LEAKAGE CURRENT (pA)
450
400
350
300
250
200
150
100
50
0
0
1
4
3
2
INPUT VOLTAGE (V)
5
6
3410 G12
MAIN
SWITCH
SYNCHRONOUS
SWITCH
Load Step
V
OUT
100mV/DIV
AC COUPLED
V
OUT
100mV/DIV
AC COUPLED
I
L
200mA/DIV
I
LOAD
200mA/DIV
4µs/DIV
V
IN
= 3.6V
V
OUT
= 1.8V
I
LOAD
= 0mA TO 300mA
3410 G15
U W
Pulse Skipping
V
OUT
10mV/DIV
AC COUPLED
Start-Up from Shutdown
RUN
2V/DIV
V
OUT
1V/DIV
I
L
200mA/DIV
V
IN
= 3.6V
V
OUT
= 1.8V
I
LOAD
= 2mA
1µs/DIV
3410 G13
SW
2V/DIV
I
L
100mA/DIV
V
IN
= 3.6V
V
OUT
= 1.8V
I
LOAD
= 128mA
100µs/DIV
3410 G14
Load Step
I
L
200mA/DIV
I
LOAD
200mA/DIV
4µs/DIV
V
IN
= 3.6V
V
OUT
= 1.8V
I
LOAD
= 30mA TO 300mA
3410 G16
3410bfa
5
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