OMO ElectronicOMO Electronic
Expand menu
Hello, Sign inMy Account
0 Cart

LTC3852EUDD#TRPBF

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P30P31-P32
LTC3852
1
3852f
TYPICAL APPLICATION
FEATURES DESCRIPTION
Low Input Voltage,
Synchronous Step-Down
DC/DC Controller
The LTC
®
3852 is a constant frequency, current mode
step-down DC/DC controller which can be powered by an
onboard charge pump. Input supplies as low as 2.7V, when
doubled by the charge pump, provide 5V to the LTC3852’s
control logic and gate drives, supporting a wide selection
of logic-level N-channel power MOSFETs.
The constant-frequency current mode architecture allows for
a phase-lockable fi xed frequency of up to 750kHz. The RUN
pin provides a precision enable threshold while the TRACK/SS
pin combines tracking and adjustable soft-start features.
The MODE/PLLIN pin selects among Burst Mode
®
oper-
ation, pulse-skipping mode, and continuous current mode.
Current foldback limits MOSFET power dissipation during
short-circuit conditions. Reverse current and current
foldback functions are disabled during soft-start. A power
good output pin indicates when the output is within ±10%
of its designed set point.
Effi ciency and Power Loss
vs Load Current
APPLICATIONS
n
Charge Pump Input Range: 2.7V to 5.5V
n
Controller Input Range: 4V to 38V
n
Integrated Charge Pump Provides 5V Gate Drive to
Logic Level MOSFETs
n
R
SENSE
or DCR Current Sensing
n
±1.25% Output Voltage Accuracy Over Temperature
n
Phase-Lockable Fixed Frequency: 250kHz to 750kHz
n
Power Good Output Voltage Monitor
n
Adjustable Soft-Start Voltage Ramping
n
Current Foldback Disabled During Start-Up
n
No Reverse Current During Soft-Start
n
Selectable Constant Frequency, Pulse-Skipping, or
Burst Mode Operation
n
Output Overvoltage Protection
n
Very Low Dropout Operation: 99% Duty Cycle
n
Available in a 24-Lead (3mm ¥ 5mm) QFN Package
n
General Purpose 3.3V Systems
n
Lithium-Ion Powered Devices
n
Distributed DC Power Systems
L, LT, LTC, LTM, Linear Technology, Burst Mode and the Linear logo are registered trademarks
and No R
SENSE
is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners. Protected by U.S. Patents including 5408150, 5481178,
5705919, 6498466, 6580258, 6611131.
PGO0D
C
+
C
–
RUN
SHDN
TRACK/SS
I
TH
MODE/PLLIN
FREQ/PLLFLTR
V
IN1
INTV
CC
TG
SW
INTV
CC
BG
SENSE
+
SENSE
–
V
FB
V
PUMP
V
IN2
GND2
GND1
0.1µF
0.1µF
4.7µF
2.1k
LTC3852
22µF
V
IN
2.7V TO 5.5V
V
OUT
1.2V
20A
3852 TA01
0.36µH
100pF
CHARGE PUMP
2.2µF
1nF
0.1µF
100k
470µF
×2
BOOST
12.1k
40.2k
1%
20k
1%
95.3k
+
ONOFF
High Effi ciency Synchronous Step-Down Converter
LOAD CURRENT (A)
12010
0
EFFICIENCY (%)
POWER LOSS (W)
100
90
80
70
60
50
40
30
20
10
0
5
4.5
4
3.5
3
2.5
2
1.5
1
0.5
3852 TA01a
EFFICIENCY
POWER LOSS
LTC3852
2
3852f
ABSOLUTE MAXIMUM RATINGS
Input Supply Voltage (V
IN1
) .........................6V to –0.3V
Top Side Driver Voltage (BOOST) ...............46V to – 0.3V
Switch Voltage (SW) ..................................40V to – 0.3V
V
PUMP
.......................................................5.5V to –0.3V
SHDN, RUN ..................................................6V to – 0.3V
V
PUMP
Short-Circuit Duration .......................... Indefi nite
V
IN2
............................................................40V to –0.3V
INTV
CC
, (BOOST-SW), RUN, PGOOD ...........6V to – 0.3V
INTV
CC
, Peak Output Current .................................50mA
SENSE
+
, SENSE
–
..........................................6V to – 0.3V
MODE/PLLIN, TRACK/SS .....................INTV
CC
to –0.3V
FREQ/PLLFLTR .....................................INTV
CC
to –0.3V
I
TH
, V
FB
........................................................3V to – 0.3V
Operating Junction Temperature (Note 2) ............. 125°C
Storage Temperature Range ..................–65°C to 125°C
(Note 1)
TOP VIEW
UDD PACKAGE
24-LEAD
(
3mm s 5mm
)
PLASTIC QFN
SENSE
–
SENSE
+
PGOOD
GND2
BG
NC
C
+
C
–
FREQ/PLLFLTR
MODE/PLLIN
SW
TG
BOOST
V
IN2
INTV
CC
V
PUMP
NC
SHDN
GND1
V
IN1
V
FB
I
TH
TRACK/SS
RUN
6
5
4
3
2
1
7
8
15
16
17
18
19
20
14
13
9101112
24 23 22 21
25
GND
T
JMAX
= 125°C, q
JA
= 38°C/W
EXPOSED PAD (PIN 25) IS GND, MUST BE SOLDERED TO PCB
PIN CONFIGURATION
ORDER INFORMATION
LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LTC3852EUDD#PBF LTC3852EUDD#TRPBF LFRJ
24-Lead (3mm ¥ 5mm) Plastic QFN
–40°C to 125°C
LTC3852IUDD#PBF LTC3852IUDD#TRPBF LFRJ
24-Lead (3mm ¥ 5mm) Plastic QFN
–40°C to 125°C
Consult LTC Marketing for parts specifi ed with wider operating temperature ranges. *The temperature grade is identifi ed 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 specifi
cations, go to: http://www
.linear.com/tapeandreel/
LTC3852
3
3852f
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Main Control Loop (Step-Down Regulator)
V
IN2
Controller Input Voltage Range
l
438V
V
FB
Regulated Feedback Voltage (Note 3); I
TH
Voltage = 1.2V
l
0.790 0.800 0.810 V
I
FB
Feedback Current (Note 3) –10 –50 nA
V
REFLNREG
Reference Voltage Line Regulation (Notes 3, 9); V
IN2
= 6V to 38V 0.002 0.02 %/V
V
LOADREG
Output Voltage Load Regulation (Note 3)
Measured in Servo Loop;
DI
TH
Voltage = 1.2V to 0.7V
l
0.01 0.1 %
Measured in Servo Loop;
DI
TH
Voltage = 1.2V to 1.6V
l
–0.01 –0.1 %
g
m
Transconductance Amplifi er g
m
(Note 3); I
TH
= 1.2V;
Sink/Source 5µA
2 mmho
I
Q(VIN2)
Controller Input DC Supply Current (Note 4) V
FB
= 0.9V
(RUN = 3.3V)
1.4 mA
Shutdown Supply Current RUN = 0V 25 50 µA
I
Q(VIN1)
Total Input DC Supply Current (Notes 4, 7) V
FB
= 0.9V
(RUN = SHDN = 3.3V)
7mA
Shutdown Supply Current (Note 7) RUN = SHDN = 0V 5 µA
UVLO Undervoltage Lockout INTV
CC
Ramping Down 3.25 V
Undervoltage Hysteresis 0.4 V
V
OVL
Feedback Overvoltage Lockout Measured at V
FB
l
0.86 0.88 0.90 V
I
SENSE
SENSE Pins Current –2.0 2.0 µA
I
TRACK/SS
Soft-Start Charge Current V
TRACK/SS
= 0V 0.5 1 2 µA
V
RUN
RUN Pin On Threshold V
RUN
Rising
l
1.1 1.22 1.35 V
V
RUN(HYS)
RUN Pin On Hysteresis 130 mV
V
SENSE(MAX)
Maximum Current Sense Threshold V
FB
= 0.7V, V
SENSE
–
= 3.3V
l
40 53 68 mV
TG R
UP
TG Driver Pull-Up On-Resistance TG High 2.2
TG R
DOWN
TG Driver Pull-Down On-Resistance TG Low 1.2
BG R
UP
BG Driver Pull-Up On-Resistance BG High 2.1
BG R
DOWN
BG Driver Pull-Down On-Resistance BG Low 1.1
TG t
r
TG t
f
Top Gate Rise Time
Top Gate Fall Time
C
LOAD
= 3300pF (Note 5) 25
25
ns
ns
BG t
r
BG t
f
Bottom Gate Rise Time
Bottom Gate Fall Time
C
LOAD
= 3300pF (Note 5) 25
25
ns
ns
TG/BG t
1D
Top Gate Off to Bottom Gate On Delay
Synchronous Switch-On Delay Time
C
LOAD
= 3300pF (Note 5) 30 ns
BG/TG t
1D
Bottom Gate Off to Top Gate On Delay
Top Switch-On Delay Time
C
LOAD
= 3300pF (Note 5) 30 ns
t
ON(MIN)
Minimum On-Time (Note 6) 90 ns
The l denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at T
A
= 25°C (Note 2), V
IN1
= 3.3V, V
IN2
= 15V, V
RUN
= 3.3V, SHDN = 0V,
MODE/PLLIN = 0V unless otherwise noted.
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P30P31-P32

LTC3852EUDD#TRPBF

Mfr. #:
Buy LTC3852EUDD#TRPBF
Manufacturer:
Analog Devices / Linear Technology
Description:
Switching Voltage Regulators Low Input Voltage Synchronous Step-Down Controller
Lifecycle:
New from this manufacturer.
Delivery:
DHL FedEx Ups TNT EMS
Payment:
T/T Paypal Visa MoneyGram Western Union

Products related to this Datasheet