step-down DC/DC converter utilizing a constant-frequency,
current mode architecture. It operates from an input voltage
range of 4.5V to 10V and provides an adjustable regulated
output voltage from 0.6V to 9.5V while delivering up to
2.5A of output current. The internal synchronous power
switch with 65mΩ on-resistance increases efficiency
and eliminates the need for an external Schottky diode.
The switching frequency can either be set by an external
resistor or synchronized to an external clock. OPTI-LOOP
®
compensation allows the transient response to be optimized
over a wide range of loads and output capacitors.
The LTC3602 can be configured for either Burst Mode op-
eration or forced continuous operation. Forced continuous
operation reduces noise and RF interference, while Burst
Mode operation provides the high efficiency at light loads.
In Burst Mode operation, external control of the burst
clamp level allows the output voltage ripple to be adjusted
according to the requirements of the application.
, LT, LTC, LTM, Burst Mode and OPTI-LOOP are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
Wide Input Voltage Range: 4.5V to 10V
2.5A Output Current
Low R
DS(ON)
Internal Switches: 65mΩ and 90mΩ
Programmable Frequency: 300kHz to 3MHz
Low Quiescent Current: 75μA
0.6V ±1% Reference Allows Low Output Voltage
99% Maximum Duty Cycle
Adjustable Burst Mode
®
Clamp
Synchronizable to External Clock
Power Good Output Voltage Monitor
Overtemperature Protection
Available in 16-Lead Exposed TSSOP and
4mm
×
4mm QFN Packages
APPLICATIONS
n
n
n
n
Point-of-Load Supplies
Portable Instruments
Server Backplane Power
Battery-Powered Devices
TYPICAL APPLICATION
3.3V, 2.5A, 1MHz Step-Down Regulator
V
IN
4.5V TO 10V
22μF
RUN
R
T
105k
2.2μH
PGOOD
TRACK/SS
4.32k
I
TH
1nF
SYNC/MODE
V
FB
PGND
475k
22pF
3602 TA01
Efficiency and Power Loss vs Load Current
100
95
V
IN
= 7V
EFFICIENCY
1000
POWER LOSS
80
75
70
65
60
0.01
0.1
1
LOAD CURRENT (A)
1
10
3602 TA01b
10000
PV
IN
INTV
CC
BOOST
0.22μF
1μF
EFFICIENCY (%)
90
85
POWER LOSS (mW)
100
LTC3602
SW
100μF
V
OUT
3.3V
2.5A
10
105k
3602fb
1
LTC3602
ABSOLUTE MAXIMUM RATINGS
(Note 1)
Input Supply Voltage (PV
IN
) ....................... –0.3V to 11V
SW (DC)...................................... –0.3V to (PV
IN
+ 0.3V)
BOOST ................................. (V
SW
–0.3V) to (V
SW
+ 6V)
RUN ........................................................... –0.3V to 11V
All Other Pins ............................................... –0.3V to 6V
Peak SW Sink and Source Current (Note 7) .............6.5A
Operating Temperature Range (Note 2)....–40°C to 85°C
Junction Temperature (Notes 5, 6)........................ 125°C
Lead Temperature
(Soldering, FE Package 10 seconds)................. 300°C
PIN CONFIGURATION
BOOST
TOP VIEW
SW
SW
SW
SW
15 PGND
14 PGND
21
13 PGND
12 PGND
11 TRACK/SS
6
R
T
7
I
TH
8
V
FB
9 10
SGND
RUN
TOP VIEW
SYNC/MODE
PGOOD
R
T
I
TH
V
FB
RUN
TRACK/SS
PGND
1
2
3
4
5
6
7
8
17
16 INTV
CC
15 PV
IN
14 BOOST
13 SW
12 SW
11 SW
10 PGND
9
PGND
PV
IN
1
PV
IN
2
INTV
CC
3
SYNC/MODE 4
PGOOD 5
20 19 18 17 16
FE PACKAGE
16-LEAD PLASTIC TSSOP
T
JMAX
= 125°C,
θ
JA
= 38°C/W,
θ
JC
= 10°C/W
EXPOSED PAD (PIN 17) IS SGND, MUST BE SOLDERED TO PCB
UF PACKAGE
20-LEAD (4mm 4mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JA
= 37°C/W,
θ
JC
= 10°C/W
EXPOSED PAD (PIN 21) IS SGND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
LTC3602EFE#PBF
LTC3602IFE#PBF
LTC3602EUF#PBF
LTC3602IUF#PBF
TAPE AND REEL
LTC3602EFE#TRPBF
LTC3602IFE#TRPBF
LTC3602EUF#TRPBF
LTC3602IUF#TRPBF
PART MARKING*
3602FE
3602FE
3602
3602
PACKAGE DESCRIPTION
16-Lead Plastic TSSOP
16-Lead Plastic TSSOP
20-Lead (4mm
×
4mm) Plastic QFN
20-Lead (4mm
×
4mm) Plastic QFN
TEMPERATURE RANGE
–40°C to 85°C
–40°C to 85°C
–40°C to 85°C
–40°C to 85°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/
ELECTRICAL CHARACTERISTICS
SYMBOL
PV
IN
V
FB
ΔV
FB(LINEREG)
ΔV
FB(LOADREG)
PARAMETER
Operating Voltage Range
Regulated Feedback Voltage
Feedback Voltage Line Regulation
Feedback Voltage Load Regulation
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 8.4V unless otherwise specified.
CONDITIONS
I
TH
= 0.7V (Note 3)
V
IN
= 5V to 10V, I
TH
= 0.7V
I
TH
= 0.36V to 0.84V
l
l
MIN
4.5
0.594
TYP
0.6
0.005
0.02
MAX
10
0.606
0.1
UNITS
V
V
%/V
%
3602fb
2
LTC3602
ELECTRICAL CHARACTERISTICS
SYMBOL
ΔV
PGOOD
R
PGOOD
I
FB
g
m
I
S
PARAMETER
Power Good Range
Power Good Resistance
FB Input Bias Current
Transconductance Amplifier g
m
Supply Current
Active Mode
Sleep Mode
Shutdown
V
CC
LDO Output Voltage
Minimum Controllable ON-Time
RUN Pin ON Threshold
TRACK/SS Pull-Up Current
Oscillator Frequency
SYNC Capture Range
Top Switch On-Resistance
Bottom Switch On-Resistance
Peak Current Limit
Switch Leakage Current
INTV
CC
Undervoltage Lockout
INTV
CC
Undervoltage Lockout Hysteresis
INTV
CC
Ramping Up
4.1
3.8
R
T
= 105k
0.8
0.3
90
67
4.5
0.1
4.2
700
5.2
1
4.3
V
RUN
Rising
l
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 8.4V unless otherwise specified.
CONDITIONS
MIN
TYP
±10
11
10
1.7
(Note 4)
500
75
0.2
4.8
0.4
5
90
0.7
1.25
1
1.2
3
1
700
100
1
5.2
μA
μA
μA
V
ns
V
μA
MHz
MHz
mΩ
mΩ
A
μA
V
mV
MAX
±12
18
UNITS
%
Ω
nA
ms
INTV
CC
t
ON, MIN
V
RUN
I
TRACK/SS
f
OSC
f
SYNC
R
DS(ON)
I
LIM
I
LSW
V
UVLO
V
UVLO, HYS
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 LTC3602E 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:
The LTC3602 is tested in a feedback loop that adjusts V
FB
to
achieve a specified error amplifier output voltage (I
TH
).
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 temperature T
A
and the power
dissipation as follows: T
J
= T
A
+ (P
D
)(θ
JA
C/W).
Note 6:
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 7:
This limit indicates the current density limitations of the internal
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