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

LTC3728LEGN-1#TRPBF

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P30P31-P32
LTC3728L-1
1
3728l1fc
TYPICAL APPLICATION
FEATURES
APPLICATIONS
DESCRIPTION
Dual, 550kHz, 2-Phase
Synchronous Regulator
The LTC
®
3728L-1 is a dual high performance step-down
switching regulator controller that drives all N-channel
synchronous power MOSFET stages. A constant frequency
current mode architecture allows phase-lockable frequency
of up to 550kHz. Power loss and noise due to the ESR of
the input capacitors are minimized by operating the two
controller output stages out of phase. The LTC3728L-1
is identical to the LTC3728L except that the LTC3728L-1
lacks the over current latchoff feature.
OPTI-LOOP compensation allows the transient response to
be optimized over a wide range of output capacitance and
ESR values. The precision 0.8V reference and power good
output indicator are compatible with future microproces-
sor generations, and a wide 4.5V to 28V (30V maximum/
35V for LTC3728LI-1) input supply range encompasses
all battery chemistries.
A RUN/SS pin for each controller provides soft-start.
Current foldback limits MOSFET dissipation during short-
circuit conditions. The FCB mode pin can select among
Burst Mode operation, constant frequency mode and
continuous inductor current mode or regulate a secondary
winding. The LTC3728L-1 includes a power good output
pin that indicates when both outputs are within 7.5% of
their designed set point.
Figure 1. High Effi ciency Dual 5V/3.3V Step-Down Converter
n
Dual, 180° Phased Controllers Reduce Required
Input Capacitance and Power Supply Induced Noise
n
OPTI-LOOP
®
Compensation Minimizes C
OUT
n
±1.5% Output Voltage Accuracy
n
Power Good Output Voltage Indicator
n
Phase-Lockable Fixed Frequency 250kHz to 550kHz
n
Over Current Latchoff Disabled
n
Wide V
IN
Range: 4.5V to 28V (35V for LTC3728LI-1)
Operation
n
Very Low Dropout Operation: 99% Duty Cycle
n
Adjustable Soft-Start Current Ramping
n
Foldback Output Current Limiting
n
Output Overvoltage Protection
n
Low Shutdown I
Q
: 20µA
n
5V and 3.3V Standby Regulators
n
3 Selectable Operating Modes: Constant Frequency,
Burst Mode
®
Operation and PWM
n
5mm × 5mm QFN and 28-Lead Narrow SSOP
Packages
n
Notebook and Palmtop Computers
n
Telecom Systems
n
Portable Instruments
n
Battery-Operated Digital Devices
n
DC Power Distribution Systems
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
Burst Mode and OPTI-LOOP are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
Protected by U.S. Patents including 5929620, 6177787, 6144199, 5471178, 5994885, 6100678.
+
4.7µF
D3
D4
M1
C
B1
, 0.1µF
R2
105k
1%
1000pF
L1
3.2µH
C
C1
220pF
1µF
CERAMIC
C
IN
22µF
50V
CERAMIC
+
C
OUT1
47µF
6V
SP
R
SENSE1
0.01Ω
R1
20k
1%
R
C1
15k
V
OUT1
5V
5A
M2
C
B2
, 0.1µF
R4
63.4k
1%
L2
3.2µH
C
C2
220pF
1000pF
+
C
OUT
56µF
6V
SP
R
SENSE2
0.01Ω
R3
20k
1%
R
C2
15k
V
OUT2
3.3V
5A
TG1 TG2
BOOST1 BOOST2
SW1 SW2
BG1 BG2
SGND
PGND
SENSE1
+
SENSE2
+
SENSE1
–
SENSE2
–
V
OSENSE1
V
OSENSE2
I
TH1
I
TH2
V
IN
PGOOD INTV
CC
RUN/SS1 RUN/SS2
V
IN
5.2V TO 28V
M1, M2: FDS6982S
3728l1 F01
C
SS1
0.1µF
C
SS2
0.1µF
LTC3728L-1
PLLIN
f
IN
500kHz
LTC3728L-1
2
3728l1fc
ABSOLUTE MAXIMUM RATINGS
Input Supply Voltage (V
IN
) .........................30V to –0.3V
Input Supply Voltage (V
IN
) LTC3728LI-1 ....35V to – 0.3V
Top Side Driver Voltages
(BOOST1, BOOST2) ............................... 36V to –0.3V
(BOOST1, BOOST2) LTC3728LI-1 .......... 38V to –0.3V
Switch Voltage (SW1, SW2) ...........................30V to –5V
Switch Voltage (SW1, SW2) LTC3728LI-1 ...35V to –0.3V
INTV
CC,
EXTV
CC
, RUN/SS1, RUN/SS2, (BOOST1-SW1),
(BOOST2-SW2), PGOOD ......................... 7V to –0.3V
INTV
CC,
EXTV
CC
LTC3728LI-1 ....................... 8V to –0.3V
SENSE1
+
, SENSE2
+
, SENSE1
–
,
SENSE2
–
Voltages .....................(1.1)INTV
CC
to –0.3V
(Note 1)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
TOP VIEW
GN PACKAGE
28-LEAD NARROW PLASTIC SSOP
28
27
26
25
24
23
22
21
20
19
18
17
16
15
RUN/SS1
SENSE1
+
SENSE
–
V
OSENSE1
PLLFLTR
PLLIN
FCB
I
TH1
SGND
3.3V
OUT
I
TH2
V
OSENSE2
SENSE2
–
SENSE2
+
PGOOD
TG1
SW1
BOOST1
V
IN
BG1
EXTV
CC
INTV
CC
PGND
BG2
BOOST2
SW2
TG2
RUN/SS2
T
JMAX
= 125°C, θ
JA
= 95°C/W
32 31 30 29 28 27 26 25
9 10 11 12 13
TOP VIEW
33
14 15 16
17
18
19
20
21
22
23
24
8
7
6
5
4
3
2
1V
OSENSE1
PLLFLTR
PLLIN
FCB
I
TH1
SGND
3.3V
OUT
I
TH2
BOOST1
V
IN
BG1
EXTV
CC
INTV
CC
PGND
BG2
BOOST2
NC
SENSE1
–
SENSE1
+
NC
RUN/SS1
PGOOD
TG1
SW1
V
OSENSE2
NC
SENSE2
–
SENSE2
+
RUN/SS2
TG2
SW2
NC
UH PACKAGE
32-LEAD (5mm s 5mm) PLASTIC QFN
T
JMAX
= 125°C, θ
JA
= 34°C/W
EXPOSED PAD (PIN 33) IS GND, MUST BE SOLDERED TO PCB
PIN CONFIGURATION
ORDER INFORMATION
LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE
LTC3728LEGN-1#PBF LTC3728LEGN-1#TRPBF LTC3728LEGN-1 28-Lead Narrow Plastic SSOP –40°C to 85°C
LTC3728LIGN-1#PBF LTC3728LIGN-1#TRPBF LTC3728LIGN-1 28-Lead Narrow Plastic SSOP –40°C to 85°C
LTC3728LEUH-1#PBF LTC3728LEUH-1#TRPBF 728LE1
32-Lead (5mm × 5mm) Plastic DFN
–40°C to 85°C
LTC3728LIUH-1#PBF LTC3728LIUH-1#TRPBF 3728L1
32-Lead (5mm × 5mm) Plastic DFN
–40°C to 85°C
LEAD BASED FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE
LTC3728LEGN-1 LTC3728LEGN-1#TR LTC3728LEGN-1 28-Lead Narrow Plastic SSOP –40°C to 85°C
LTC3728LIGN-1 LTC3728LIGN-1#TR LTC3728LIGN-1 28-Lead Narrow Plastic SSOP –40°C to 85°C
LTC3728LEUH-1 LTC3728LEUH-1#TR 728LE1
32-Lead (5mm × 5mm) Plastic DFN
–40°C to 85°C
LTC3728LIUH-1 LTC3728LIUH-1#TR 3728L1
32-Lead (5mm × 5mm) Plastic DFN
–40°C to 85°C
Consult LTC Marketing for parts specifi ed with wider operating temperature ranges.
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/
PLLIN, PLLFLTR, FCB, Voltage .............. INTV
CC
to –0.3V
I
TH1,
I
TH2
, V
OSENSE1
, V
OSENSE2
Voltages .... 2.7V to –0.3V
Peak Output Current <10µs (TG1, TG2, BG1, BG2) .....3A
INTV
CC
Peak Output Current ..................................40mA
Operating Temperature Range (Note 7).... –40°C to 85°C
Junction Temperature (Note 2) ............................. 125°C
Storage Temperature Range ................... –65°C to 125°C
Refl ow Peak Body Temperature (UH Package) ...... 260°C
Lead Temperature (Soldering, 10 sec)
GN Package ...................................................... 300°C
LTC3728L-1
3
3728l1fc
ELECTRICAL CHARACTERISTICS
The l denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at T
A
= 25°C. V
IN
= 15V, V
RUN/SS1, 2
= 5V unless otherwise noted.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Main Control Loops
V
OSENSE1, 2
Regulated Feedback Voltage (Note 3); I
TH1, 2
Voltage = 1.2V
●
0.788 0.800 0.812 V
I
VOSENSE1, 2
Feedback Current (Note 3) –5 –50 nA
V
REFLNREG
Reference Voltage Line Regulation V
IN
= 3.6V to 30V (Note 3) 0.002 0.02 %/V
V
LOADREG
Output Voltage Load Regulation (Note 3)
Measured in Servo Loop; ∆I
TH
Voltage = 1.2V to 0.7V
Measured in Servo Loop; ∆I
TH
Voltage = 1.2V to 2.0V
●
●
0.1
–0.1
0.5
–0.5
%
%
g
m1, 2
Transconductance Amplifi er g
m
I
TH1, 2
= 1.2V; Sink/Source 5µA; (Note 3) 1.3 mmho
g
mGBW1, 2
Transconductance Amplifi er GBW I
TH1, 2
= 1.2V; (Note 3) 3 MHz
I
Q
Input DC Supply Current
Normal Mode
Shutdown
(Note 4)
V
IN
= 15V; EXTV
CC
Tied to V
OUT1
; V
OUT1
= 5V
V
RUN/SS1, 2
= 0V
450
20 35
µA
µA
V
FCB
Forced Continuous Threshold
●
0.76 0.800 0.84 V
I
FCB
Forced Continuous Pin Current V
FCB
= 0.85V –0.50 –0.18 –0.1 µA
V
BINHIBIT
Burst Inhibit (Constant Frequency)
Threshold
Measured at FCB pin 4.3 4.8 V
UVLO Undervoltage Lockout V
IN
Ramping Down
●
3.5 4 V
V
OVL
Feedback Overvoltage Lockout Measured at V
OSENSE1, 2
●
0.84 0.86 0.88 V
I
SENSE
Sense Pins Total Source Current (Each Channel); V
SENSE1
–
, 2
–
= V
SENSE1
+
, 2
+
= 0V –90 –60 µA
DF
MAX
Maximum Duty Factor In Dropout 98 99.4 %
I
RUN/SS1, 2
Soft-Start Charge Current V
RUN/SS1, 2
= 1.9V 0.5 1.2 µA
V
RUN/SS1, 2
ON RUN/SS Pin ON Threshold V
RUN/SS1,
V
RUN/SS2
Rising 1.0 1.5 2.0 V
V
SENSE(MAX)
Maximum Current Sense Threshold V
OSENSE1, 2
= 0.7V,V
SENSE1
–
, 2
– = 5V
V
OSENSE1, 2
= 0.7V,V
SENSE1
–
, 2
– = 5V
●
65
62
75
75
85
88
mV
mV
TG1, 2 t
r
TG1, 2 t
f
TG Transition Time:
Rise Time
Fall Time
(Note 5)
C
LOAD
= 3300pF
C
LOAD
= 3300pF
55
55
100
100
ns
ns
BG1, 2 t
r
BG1, 2 t
f
BG Transition Time:
Rise Time
Fall Time
(Note 5)
C
LOAD
= 3300pF
C
LOAD
= 3300pF
45
45
100
90
ns
ns
TG/BG t
1D
Top Gate Off to Bottom Gate On Delay
Synchronous Switch-On Delay Time C
LOAD
= 3300pF Each Driver 80 ns
BG/TG t
2D
Bottom Gate Off to Top Gate On Delay
Top Switch-On Delay Time C
LOAD
= 3300pF Each Driver 80 ns
t
ON(MIN)
Minimum On-Time Tested with a Square Wave (Note 6) 100 ns
INTV
CC
Linear Regulator
V
INTVCC
Internal V
CC
Voltage 6V < V
IN
< 30V, V
EXTVCC
= 4V 4.8 5.0 5.2 V
V
LDO
INT INTV
CC
Load Regulation I
CC
= 0 to 20mA, V
EXTVCC
= 4V 0.2 2.0 %
V
LDO
EXT EXTV
CC
Voltage Drop I
CC
= 20mA, V
EXTVCC
= 5V 100 200 mV
V
EXTVCC
EXTV
CC
Switchover Voltage I
CC
= 20mA, EXTV
CC
Ramping Positive
●
4.5 4.7 V
V
LDOHYS
EXTV
CC
Hysteresis 0.2 V
Oscillator and Phase-Locked Loop
f
NOM
Nominal Frequency V
PLLFLTR
= 1.2V 360 400 440 kHz
f
LOW
Lowest Frequency V
PLLFLTR
= 0V 230 260 290 kHz
f
HIGH
Highest Frequency V
PLLFLTR
≥ 2.4V 480 550 590 kHz
R
PLLIN
PLLIN Input Resistance 50 k
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P30P31-P32

LTC3728LEGN-1#TRPBF

Mfr. #:
Buy LTC3728LEGN-1#TRPBF
Manufacturer:
Analog Devices / Linear Technology
Description:
Switching Voltage Regulators 2x, 550kHz, 2-PhSync Reg
Lifecycle:
New from this manufacturer.
Delivery:
DHL FedEx Ups TNT EMS
Payment:
T/T Paypal Visa MoneyGram Western Union

Products related to this Datasheet