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LTC3727EG-1#TRPBF

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1
LTC3727/LTC3727-1
3727fc
High Efficiency, 2-Phase
Synchronous Step-Down Switching Regulators
Figure 1. High Efficiency Dual 12V/5V Step-Down Converter
■
Wide Output Voltage Range: 0.8V ≤ V
OUT
≤ 14V
■
Out-of-Phase Controllers Reduce Required Input
Capacitance and Power Supply Induced Noise
■
OPTI-LOOP
®
Compensation Minimizes C
OUT
■
±1% Output Voltage Accuracy
■
Power Good Output Voltage Monitor
■
Phase-Lockable Fixed Frequency 250kHz to 550kHz
■
Latched Short-Circuit Shutdown (LTC3727 Only)
■
Dual N-Channel MOSFET Synchronous Drive
■
Wide V
IN
Range: 4V to 36V Operation
■
Very Low Dropout Operation: 99% Duty Cycle
■
Adjustable Soft-Start Current Ramping
■
Foldback Output Current Limiting
■
Output Overvoltage Protection
■
Low Shutdown I
Q
: 20μA
■
Selectable Constant Frequency or Burst Mode
®
Operation
■
Small 28-Lead SSOP Package
■
LTC3727-1 Also Available in the 5mm × 5mm QFN
Package
The LTC
®
3727/LTC3727-1 are high performance dual
step-down switching regulator controllers that drive all
N-channel synchronous power MOSFET stages. A con-
stant 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.
OPTI-LOOP compensation allows the transient response
to be optimized over a wide range of output capacitance and
ESR values. There is a precision 0.8V reference and a power
good output indicator. A wide 4V to 30V (36V maximum)
input supply range encompasses all battery chemistries.
A RUN/SS pin for each controller provides soft-start, and
on the LTC3727GN, optional timed, short-circuit shut-
down. Current foldback limits MOSFET heat dissipation
during short-circuit conditions when overcurrent latchoff
is disabled. Output overvoltage protection circuitry latches
on the bottom MOSFET until V
OUT
returns to normal. The
FCB mode pin can select among Burst Mode, constant
frequency mode and continuous inductor current mode or
regulate a secondary winding.
■
Telecom Systems
■
Automotive Systems
■
Battery-Operated Digital Devices
+
4.7μF
M2
M1
0.1μF
105k
1%
1000pF
8μH
220pF
1μF
CERAMIC
22μF
50V
CERAMIC
+
47μF
6V
SP
0.015Ω
20k
1%
15k
V
OUT1
5V
5A
M4
M3
0.1μF
280k
1%
15μH
220pF
1000pF
+
56μF
15V
SP
0.015Ω
20k
1%
15k
V
OUT2
12V
4A
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
18V TO 28V
M1, M2, M3, M4: FDS6680A
3727 F01
0.1μF
0.1μF
LTC3727/
LTC3727-1
PLLIN
DESCRIPTIO
U
FEATURES
APPLICATIO S
U
TYPICAL APPLICATIO
U
, 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
5481178, 5929620, 6177787, 6144194, 6100678, 5408150, 6580258, 6304066, 5705919.
2
LTC3727/LTC3727-1
3727fc
ORDER PART
NUMBER
LTC3727EG
LTC3727EG-1
LTC3727IG-1
Input Supply Voltage (V
IN
).........................36V to –0.3V
Top Side Driver Voltages
(BOOST1, BOOST2) ...................................42V to –0.3V
Switch Voltage (SW1, SW2) .........................36V to –5V
INTV
CC,
EXTV
CC
, (BOOST1-SW1),
(BOOST2-SW2) ........................................8.5V to –0.3V
RUN/SS1, RUN/SS2, PGOOD ..................... 7V to –0.3V
SENSE1
+
, SENSE2
+
, SENSE1
–
,
SENSE2
–
Voltages .....................................14V to –0.3V
PLLIN, PLLFLTR, FCB Voltages ........... INTV
CC
to –0.3V
T
JMAX
= 125°C, θ
JA
= 95°C/W
ABSOLUTE AXI U RATI GS
WWWU
PACKAGE/ORDER I FOR ATIO
UU
W
1
2
3
4
5
6
7
8
9
10
11
12
13
14
TOP VIEW
G PACKAGE
28-LEAD PLASTIC SSOP
28
27
26
25
24
23
22
21
20
19
18
17
16
15
RUN/SS1
SENSE1
+
SENSE1
–
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
Consult LTC Marketing for parts specified with wider operating temperature ranges.
(Note 1)
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 ................................ 50mA
Operating Temperature Range (Note 2) .. –40°C to 85°C
Junction Temperature (Note 3)............................. 125°C
Storage Temperature Range ................. –65°C to 125°C
Lead Temperature
(Soldering, 10 sec, G Package)............................. 300°C
Solder Reflow Temperature (UH Package) ........... 265°C
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 × 5mm) PLASTIC QFN
ORDER PART
NUMBER
LTC3727EUH-1
T
JMAX
= 125°C, θ
JA
= 34°C/W
EXPOSED PAD (PIN 33) IS SGND
(MUST BE SOLDERED TO PCB)
UH PART
MARKING
37271
The
● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 15V, V
RUN/SS1, 2
= 5V unless otherwise noted.
ELECTRICAL CHARACTERISTICS
Order Options Tape and Reel: Add #TR Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking: http://www.linear.com/leadfree/
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Main Control Loops
V
OSENSE1, 2
Regulated Feedback Voltage (Note 4); I
TH1, 2
Voltage = 1.2V ● 0.792 0.800 0.808 V
I
VOSENSE1, 2
Feedback Current (Note 4) –5 – 50 nA
V
REFLNREG
Reference Voltage Line Regulation V
IN
= 3.6V to 30V (Note 4) 0.002 0.02 %/V
3
LTC3727/LTC3727-1
3727fc
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 15V, V
RUN/SS1, 2
= 5V unless otherwise noted.
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
LOADREG
Output Voltage Load Regulation (Note 4)
Measured in Servo Loop; ΔI
TH
Voltage = 1.2V to 0.7V ● 0.1 0.5 %
Measured in Servo Loop; ΔI
TH
Voltage = 1.2V to 2.0V ● –0.1 –0.5 %
g
m1, 2
Transconductance Amplifier g
m
I
TH1, 2
= 1.2V; Sink/Source 5μA (Note 4) 1.3 mmho
g
mGBW1, 2
Transconductance Amplifier GBW I
TH1, 2
= 1.2V (Note 4) 3 MHz
I
Q
Input DC Supply Current (Note 5)
Normal Mode V
IN
= 15V, EXTV
CC
Tied to V
OUT1
, V
OUT1
= 8.5V 670 μA
Shutdown V
RUN/SS1, 2
= 0V 20 35 μA
V
FCB
Forced Continuous Threshold ● 0.76 0.800 0.84 V
I
FCB
Forced Continuous Pin Current V
FCB
= 0.85V – 0.30 – 0.18 – 0.05 μA
V
BINHIBIT
Burst Inhibit (Constant Frequency) Measured at FCB pin 6.8 7.3 V
Threshold
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 – 85 – 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 1.9 V
V
RUN/SS1, 2
LT RUN/SS Pin Latchoff Arming Threshold V
RUN/SS1,
V
RUN/SS2
Rising from 3V (LTC3727 Only) 4.1 4.5 V
I
SCL1, 2
RUN/SS Discharge Current Soft-Short Condition V
OSENSE1, 2
= 0.5V, 0.5 2 4 μA
V
RUN/SS1, 2
= 4.5V (LTC 3727 Only)
I
SDLHO
Shutdown Latch Disable Current V
OSENSE1, 2
= 0.5V (LTC3727 Only) 1.6 5 μA
V
SENSE(MAX)
Maximum Current Sense Threshold V
OSENSE1, 2
= 0.7V,V
SENSE1
–
, 2
– = 12V
● 105 135 165 mV
TG Transition Time: (Note 6)
TG1, 2 t
r
Rise Time C
LOAD
= 3300pF 50 90 ns
TG1, 2 t
f
Fall Time C
LOAD
= 3300pF 50 90 ns
BG Transition Time: (Note 6)
BG1, 2 t
r
Rise Time C
LOAD
= 3300pF 40 90 ns
BG1, 2 t
f
Fall Time C
LOAD
= 3300pF 40 80 ns
TG/BG t
1D
Top Gate Off to Bottom Gate On Delay C
LOAD
= 3300pF Each Driver 90 ns
Synchronous Switch-On Delay Time
BG/TG t
2D
Bottom Gate Off to Top Gate On Delay C
LOAD
= 3300pF Each Driver 90 ns
Top Switch-On Delay Time
t
ON(MIN)
Minimum On-Time Tested with a Square Wave (Note 7) 180 ns
INTV
CC
Linear Regulator
V
INTVCC
Internal V
CC
Voltage 8.5V < V
IN
< 30V, V
EXTVCC
= 6V 7.2 7.5 7.8 V
V
LDO
INT INTV
CC
Load Regulation I
CC
= 0mA to 20mA, V
EXTVCC
= 6V 0.2 1.0 %
V
LDO
EXT EXTV
CC
Voltage Drop I
CC
= 20mA, V
EXTVCC
= 8.5V 70 160 mV
V
EXTVCC
EXTV
CC
Switchover Voltage I
CC
= 20mA, EXTV
CC
Ramping Positive ● 6.9 7.3 V
V
LDOHYS
EXTV
CC
Hysteresis 0.3 V
Oscillator and Phase-Locked Loop
f
NOM
Nominal Frequency V
PLLFLTR
= 1.2V 350 380 430 kHz
f
LOW
Lowest Frequency V
PLLFLTR
= 0V 220 255 290 kHz
f
HIGH
Highest Frequency V
PLLFLTR
≥ 2.4V 460 530 580 kHz
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LTC3727EG-1#TRPBF

Mfr. #:
Buy LTC3727EG-1#TRPBF
Manufacturer:
Analog Devices / Linear Technology
Description:
Switching Voltage Regulators Dual, 2-Phase Step-Down Controller
Lifecycle:
New from this manufacturer.
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