nous buck regulator in which the output voltage is pro-
grammed with a single external resistor. The accurate
internally generated 50µA current source on the ISET pin
allows the user to program an output voltage from 0V
to 0.5V below V
IN
. The user can also directly drive the
ISET pin with an external voltage supply to program the
converter’s V
OUT
. The V
OUT
voltage is fed directly back
to the error amplifier to be regulated to the ISET voltage.
The operating supply voltage range for the SV
IN
pin is from
15V down to 4V, while the PV
IN
pin’s voltage range is 15V
down to 1.5V, making it suitable for dual Li-Ion batteries
and for taking power from a 12V or 5V rail.
The operating frequency is programmable from 400kHz
to 4MHz with an external R
T
resistor. Higher switching fre-
quency allows the use of smaller surface mount inductors
while lower frequency allows for higher power efficiency.
The unique constant-frequency/controlled on-time
architecture is ideal for high step-down ratio applications
that are operating at high frequency while demanding fast
transient response.
L,
LT, LTC, LTM, OPTI-LOOP Silent Switcher, Linear Technology and the Linear logo are
,
registered trademarks of Analog Devices, Inc. All other trademarks are the property of their
respective owners. Protected by U.S. Patents, including 5481178, 5705919, 5847554, 6580258.
n
n
Single Resistor Programmable V
OUT:
0V to V
IN
– 0.5V
Silent Switcher
®
Architecture
I
ISET
Accuracy: ±1%
Tight V
OUT
Regulation Across V
OUT
Range
Output Current Monitor Accuracy: ±5%
Programmable Wire Drop Compensation
Easy to Parallel for Higher Current and Heat Spreading
Input Supply Voltage Regulation Loop
High Efficiency: Up to 96%
Output Current: ±5A
Integrated N-MOSFETs (60mΩ Top & 30mΩ Bottom)
Adjustable Switching Frequency: 400kHz to 4MHz
V
IN
Range: 4V to 15V
Current Mode Operation for Excellent Line and Load
Transient Response
Shutdown Mode Draws Less Than 1µA Supply Current
Low Profile 24-Lead 3mm
×
5mm QFN Package
Tracking Supply or DDR Memory Supply
ASIC Substrate Biasing
Point-of-Load (POL) Power Supply
Portable Instruments, Battery-Powered Equipment
Thermo Electric Cooler (TEC) Systems
applicaTions
n
n
n
n
n
Typical applicaTion
V
IN
(5.5V TO 15V)
PV
IN
SV
IN
RUN
22µF
ERROR
AMP
50µA
LTC3623EUD
0.1µF
EFFICIENCY (%)
PWM
CONTROL
AND
SWITCH
DRIVER
1µH
V
OUT
5V
5A
47µF
LOAD
PGND
V
OUT
I
OUT
/50k
PGOOD
INTV
CC
MODE/
SYNC
IMON
PGFB
ISET
VIN_REG
ITH
RT
BOOST
100
90
80
70
60
50
40
30
20
10
Efficiency and Power Loss
vs Load Current
3.0
V
IN
= 12V
V
OUT
= 5V
DCM
POWER
LOSS
CCM
2.4
POWER LOSS (W)
SW
1.8
1.2
CCM
DCM
0.01
0.1
1
LOAD CURRENT (A)
10
3623 TA01a
0.6
0
0.001
3623 TA01
0
100k
0.1µF
10k
10nF
1µF
3623fa
For more information
www.linear.com/LTC3623
1
LTC3623
absoluTe MaxiMuM raTings
(Note 1)
pin conFiguraTion
TOP VIEW
VIN_REG
IMON
20 PGFB
19 INTV
CC
18 BOOST
25
PGND
17 S
VIN
16 P
VIN
15 SW
14 NC
13 V
OUT
9 10 11 12
PGND
PGND
PGND
PGND
ITH
ISET 1
PGOOD 2
RUN 3
GSNS 4
PV
IN
5
SW 6
NC 7
MODE/SYNC 8
PV
IN
, SV
IN
Voltage ..................................... –0.3V to 17V
V
OUT
, ISET Voltage .........................................–0.3 to V
IN
BOOST Voltage .............................. SW –0.3V to SW+6V
RUN Voltage.............................................. –0.3V to SV
IN
MODE/SYNC Voltage ................................... –0.3V to 6V
ITH, RT, VIN_REG Voltage .................... –0.3V to INTV
CC
IMON, PGOOD, PGFB Voltage ............... –0.3V to INTV
CC
GSNS Voltage .............................................–0.3V to 12V
Operating Junction Temperature Range
(Notes 4, 5)............................................. –40°C to 125°C
24 23 22 21
UDD PACKAGE
24-LEAD (3mm
×
5mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JA
= 36°C/W
EXPOSED PAD (PIN 25) IS GND, MUST BE SOLDERED TO PCB
orDer inForMaTion
LEAD FREE FINISH
LTC3623EUDD#PBF
LTC3623IUDD#PBF
TAPE AND REEL
(http://www.linear.com/product/LTC3623#orderinfo)
PART MARKING
LGMW
LGMW
PACKAGE DESCRIPTION
24-Lead (3mm
×
5mm) Plastic QFN
24-Lead (3mm
×
5mm) Plastic QFN
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
LTC3623EUDD#TRPBF
LTC3623IUDD#TRPBF
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/.
Some packages are available in 500 unit reels through
designated sales channels with #TRMPBF suffix.
RT
2
3623fa
For more information
www.linear.com/LTC3623
LTC3623
The
l
denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at T
A
= 25°C. (Note 4) V
IN
= 12V, unless otherwise noted.
SYMBOL PARAMETER
SV
IN
PV
IN
V
OUT
I
ISET
ISET
Signal V
IN
Supply Range
Power V
IN
Supply Range
V
OUT
Range (Note 6)
Reference Current
V
IN
= 15V
25°C
25°C to 130°C
–45°C to 25°C
V
IN
– ISET
V
IN
= 5V to 15V
I
LOAD
= 0 to 5A
I
TH
= 0.9V to 1.6V
ISET = 3V
ITH = 1.2V
RUN = 0
Mode = 0, R
T
= 33.2k
–4.5
0.21
0.28
0
1.45
30
100
l
l
elecTrical characTerisTics
CONDITIONS
MIN
4
1.5
0
49.5
49
49.5
–10
TYP
MAX
15
15
14.5
UNITS
V
V
V
µA
µA
µA
mV
nA/V
%
%
l
l
50
50
50
360
50.5
50.5
51.5
10
ISET Dropout Voltage
ISET Line Regulation
ISET Load Regulation (Note 6)
V
OUT
Load Regulation
EA’s Input Offset
0.5
0.05
4.5
0.35
5
1.75
mV
mS
µA
mA
ns
ns
g
m
(EA)
I
Q
t
on(min)
t
off(min)
I
LIM
R
TOP
R
BOTTOM
V
INTVCC
V
UVLO
V
RUN
Error Amplifier Transconductance
Input DC Supply Current (Note 2)
Shutdown
Discontinuous
Minimum On Time (Note 6)
Minimum Off Time (Note 6)
Current Limit
Negative Current Limit
Top Switch ON Resistance
Bottom Switch On Resistance
Internal V
CC
Voltage
INTV
CC
Undervoltage Lockout Threshold
UVLO Hysteresis
Run Threshold
Run Hysteresis
Run Leakage
INTV
CC
Load Regulation
5.2
–5
6.2
–6.5
60
30
7.4
–9
A
mΩ
mΩ
V
5.5V < V
IN
< 15V
INTV
CC
Rising
RUN Rising
RUN = 15V
I
LOAD
= 0 to 20mA
PGFB Rising
0.585
l
5
3.6
1.2
3.8
0.36
1.45
0.34
0
0.5
0.63
15
0.67
1.67
1
4
V
V
V
V
µA
%
V
mV
OV
Output Overvoltage
PGFB Upper Threshold
PGFB OV Hysteresis
Output Undervoltage
PGFB Lower Threshold
PGFB UV Hysteresis
PGOOD Pull-Down Resistance
PGOOD Leakage
Frequency
MODE/SYNC Threshold
UV
PGFB Falling
0.5
0.54
15
0.575
V
mV
Ω
R
PGOOD
f
OSC
5mA Load
R
T
= 33.2k
R
T
= INTV
CC
MODE V
IL(MAX)
MODE V
IH(MIN)
SYNC V
IH(MIN)
SYNC V
IL(MAX)
MODE/SYNC = 5V
l
100
1
0.94
0.75
4.5
2.5
10
1.45
1
1
1.07
1.22
0.4
0.4
µA
MHz
MHz
V
V
V
V
µA
V
3623fa
MODE/SYNC Pin Current
VIN_REG Input Voltage Regulation Reference (Note 6)
For more information
www.linear.com/LTC3623
3
LTC3623
The
l
denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at T
A
= 25°C. (Note 4) V
IN
= 12V, unless otherwise noted.
SYMBOL PARAMETER
V
OUT
Resistance to GND
VINOV
I
IMON
V
IN
Overvoltage Lockout
V
IN
0V Hystersis
I
MON
Current Limit Threshold
IMON Gain
I
LOAD
= 5A, Not Switching
2.15
20
V
IN
Rising
15.5
CONDITIONS
MIN
TYP
600
16.8
1.4
2.35
21
2.55
22
MAX
UNITS
kΩ
V
V
V
µA/A
elecTrical characTerisTics
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. Absolute Maximum Ratings are those values
beyond which the life of a device may be impaired.
Note 2:
Dynamic supply current is higher due to the internal gate charge
being delivered at the switching frequency.
Note 3:
The LTC3623 is tested in a feedback loop that adjusts V
OUT
to
achieve a specified error amplifier output voltage (I
TH
).
Note 4:
The LTC3623 is tested under pulsed load conditions such that
T
J
≈
T
A
. The LTC3623E 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 LTC3623I is guaranteed over the full –40°C to 125°C operating
junction temperature range. Note that the maximum ambient temperature
consistent with these specifications is determined by specific operating
conditions in conjunction with board layout, the rated package thermal
impedance and other environmental factors. The junction temperature
(T
J
, in °C) is calculated from the ambient temperature (T
A
, in °C) and
power dissipation (P
D
, in watts) according to the formula:
T
J
= T
A
+ (P
D
•
θ
JA
), where
θ
JA
(in °C/W) is the package thermal
impedance.
Note 5:
This IC includes overtemperature protection that is intended
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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