step-down DC/DC converter. Intended for medium power
applications, it operates from a 2.5V to 5.5V input voltage
range and has a user-configurable operating frequency up
to 4MHz, allowing the use of tiny, low cost capacitors and
inductors 1mm or less in height. The output voltage is
adjustable from 0.6V to 5.5V. Internal synchronous power
switches provide high efficiency. The LTC3565’s current
mode architecture and external compensation allow the
transient response to be optimized over a wide range of
loads and output capacitors.
The LTC3565 can be configured for automatic power
saving Burst Mode operation (I
Q
= 40µA) to reduce gate
charge losses when the load current drops below the level
required for continuous operation. For reduced noise and
RF interference, the SYNC/MODE pin can be configured to
skip pulses or provide forced continuous operation.
To further maximize battery life, the P-channel MOSFET
is turned on continuously in dropout (100% duty cycle).
In shutdown, the device draws <1µA.
L,
LT, LTC, LTM, Linear Technology the Linear logo, Burst Mode and OPTI-LOOP are registered
trademarks of Linear Technology Corporation. Hot Swap and ThinSOT are trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
Protected by U.S. Patents including 5481178, 6580258, 6498466, 6611131.
n
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High Efficiency: Up to 95%
V
IN
Range: 2.5V to 5.5V
High Frequency Operation: Up to 4MHz
Selectable Low Ripple (Typical 25mV
p-p
)
Burst Mode
®
Operation: I
Q
= 40µA
Stable with Ceramic Capacitors
Uses Tiny Capacitors and Inductor
Low R
DS(ON)
Internal Switches: 0.15Ω
Current Mode Operation for Excellent Line
and Load Transient Response
Short-Circuit Protected
Low Dropout Operation: 100% Duty Cycle
Low Shutdown Current: I
Q
≤ 1µA
Output Voltages from 0.6V to 5V
Synchronizable to External Clock
Supports Pre-Biased Outputs
Small 10-Lead (3mm
×
3mm) DFN or MSOP Package
applications
n
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Notebook Computers
Digital Cameras
Cellular Phones
Handheld Instruments
Board Mounted Power Supplies
typical application
Step-Down 2.5V/1.25A Regulator
V
IN
2.5V TO 5.5V
22µF
EFFICIENCY (%)
SYNC/MODE SV
IN
PV
IN
RUN
PGOOD
ITH
12.1k
RT
V
FB
22pF
GND
680pF
191k
931k
294k
LTC3565
SW
2.2µH
V
OUT
2.5V
1.25A
22µF
Efficiency and Power Loss vs Output Current
100
90
80
70
60
50
40
30
20
10
0
0.1
1
V
IN
= 2.7V
V
IN
= 3.6V
V
IN
= 4.2V
100
1000
10
OUTPUT CURRENT (mA)
0.01
0.1
POWER LOSS (W)
1
0.001
0.0001
10000
3565 TA01b
3565 TA01a
3565fa
LTC3565
absolute MaxiMuM ratings
(Note 1)
PV
IN
, SV
IN
Voltages .................................... –0.3V to 6V
V
FB
, ITH Voltages ......................... –0.3V to (V
IN
+ 0.3V)
SYNC/MODE, PGOOD Voltage ..... –0.3V to (V
IN
+ 0.3V)
SW Voltage (DC) .......................... –0.3V to (V
IN
+ 0.3V)
RUN Voltage ............................................... –0.3V to 6V
Operating Junction Temperature Range
(Notes 2, 5, 8) ........................................ –40°C to 125°C
Storage Temperature Range .................. –65°C to 125°C
Lead Temperature (Soldering, 10 sec)................... 300°C
pin conFiguration
TOP VIEW
RT
RUN
SYNC/MODE
SW
GND
1
2
3
4
5
11
GND
10 ITH
9 V
FB
8 PGOOD
7 SV
IN
6 PV
IN
TOP VIEW
RT
RUN
SYNC/MODE
SW
GND
1
2
3
4
5
11
GND
10
9
8
7
6
ITH
V
FB
PGOOD
SV
IN
PV
IN
DD PACKAGE
10-LEAD (3mm × 3mm) PLASTIC DFN
T
JMAX
= 125°C,
θ
JA
= 43°C/W,
θ
JC
= 7.5°C/W
EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB
MSE PACKAGE
10-LEAD PLASTIC MSOP
T
JMAX
= 125°C,
θ
JA
= 40°C/W,
θ
JC
= 10°C/W
EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB
orDer inForMation
LEAD FREE FINISH
LTC3565EDD#PBF
LTC3565IDD#PBF
LTC3565EMSE#PBF
LTC3565IMSE#PBF
TAPE AND REEL
LTC3565EDD#TRPBF
LTC3565IDD#TRPBF
LTC3565EMSE#TRPBF
LTC3565IMSE#TRPBF
PART MARKING*
LTDNR
LTDNR
LTDVJ
LTDVJ
PACKAGE DESCRIPTION
10-Lead (3mm × 3mm) Plastic DFN
10-Lead (3mm × 3mm) Plastic DFN
10-Lead Plastic MSOP
10-Lead Plastic MSOP
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
–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.
Consult LTC Marketing for information on non-standard lead based finish parts.
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
junction temperature range, otherwise specifications are at T
J
= 25°C. V
IN
= 3.6V, R
T
= 125k unless otherwise specified. (Note 2)
SYMBOL
V
IN
I
FB
V
FB
ΔV
LINEREG
ΔV
LOADREG
g
m(EA)
PARAMETER
Operating Voltage Range
Feedback Pin Input Current
Feedback Voltage
Reference Voltage Line Regulation
Output Voltage Load Regulation
Error Amplifier Transconductance
(Note 3)
(Note 3)
V
IN
= 2.5V to 5.5V
ITH = 0.55V to 0.9V
ITH Pin Load = ±5µA (Note 3)
l
l
electrical characteristics
CONDITIONS
MIN
2.5
0.588
TYP
MAX
5.5
50
UNITS
V
nA
V
%/V
%
µS
0.6
0.04
0.02
300
0.612
0.2
0.2
3565fa
LTC3565
The
l
denotes the specifications which apply over the full operating
junction temperature range, otherwise specifications are at T
J
= 25°C. V
IN
= 3.6V, R
T
= 125k unless otherwise specified. (Note 2)
SYMBOL
I
S
PARAMETER
Input DC Supply Current (Note 4)
Active Mode
Sleep Mode
Shutdown
Oscillator Frequency
Synchronization Frequency
Peak Switch Current Limit
Top Switch On-Resistance
Bottom Switch On-Resistance
I
SW(LKG)
V
RUN
I
RUN
V
UVLO
PGOOD
R
PGOOD
PGOOD Blanking
V
SYNC-MODE
t
SOFT-START
Pulse Skip
Force Continuous
Burst
Switch Leakage Current
RUN Threshold
RUN Leakage Current
Undervoltage Lockout Threshold
Power Good Threshold
Power Good Pull-Down On-Resistance
V
IN
Ramping Down
V
FB
Ramping Up from 0.45V to 0.6V
V
FB
Ramping Down from 0.69V to 0.6V
V
FB
Step from 0V to 0.6V
V
FB
Step from 0.6V to 0V
1.1
V
IN
– 0.75
0.6
CONDITIONS
V
SYNC/MODE
= 3.6V, V
FB
= 0.55V
V
SYNC/MODE
= 3.6V, V
FB
= 0.8V
V
RUN
= 0V
RT = 125k
(Note 7)
(Note 7)
V
IN
= 3V, V
FB
= 0.5V
MSE Package
DD Package (Note 6)
MSE Package
DD Package (Note 6)
V
IN
= 5.5V, V
RUN
= 0V, V
FB
= 0V
l
l
electrical characteristics
MIN
TYP
330
40
0.1
1.5
MAX
450
60
1
1.7
4
4
2.5
0.2
0.18
1
1.5
±1
2.2
UNITS
µA
µA
µA
MHz
MHz
MHz
A
Ω
Ω
Ω
Ω
µA
V
µA
V
%
%
Ω
µs
µs
V
V
V
ms
f
OSC
f
SYNC
I
LIM
R
DS(ON)
1.3
0.4
1.5
2.1
0.15
0.15
0.13
0.13
0.01
0.3
0.8
±0.01
1.9
–7
7
15
40
105
20
0.63
V
IN
– 1.05
0.9
1.2
10% to 90% of Regulation
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 LTC3565E is guaranteed to meet performance specifications
from 0°C to 85°C junction temperature. Specifications over the –40°C
to 125°C operating junction temperature range are assured by design,
characterization and correlation with statistical process controls. The
LTC3565I is guaranteed over the full –40°C to 125°C operating junction
temperature range. Note that the maximum ambient temperature is
determined by specific operating conditions in conjunction with board
layout, the rated package thermal resistance and other environmental
factors.
Note 3:
The LTC3565 is tested in a feedback loop which servos V
FB
to the
midpoint for the error amplifier (V
ITH
= 0.7V).
Note 4:
Dynamic supply current is higher due to the internal gate charge
being delivered at the switching frequency.
Note 5:
T
J
is calculated from the ambient T
A
and power dissipation P
D
according to the following formulas:
LTC3565EDD: T
J
= T
A
+ (P
D
• 43°C/W)
LTC3565EMSE: T
J
= T
A
+ (P
D
• 40°C/W)
Note 6:
Switch on-resistance is guaranteed by correlation to wafer level
measurements and assured by design characterization and correlation with
statistical process controls.
Note 7:
4MHz operation is guaranteed by design but not production tested
and is subject to duty cycle limitations (see Applications Information).
Note 8:
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
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