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LTC3727AIG-1#TRPBF

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P30P31-P32
LTC3727A-1
1
3727a1fa
TYPICAL APPLICATION
DESCRIPTION
High Effi ciency, 2-Phase
Synchronous Step-Down
Switching Regulators
The LTC
®
3727A-1 is a high performance dual 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 LTC3727A-1 is an improved version of the LTC3727
family of parts. It has smaller output ripple while in the
drop-out condition and shorter minimum on-time.
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. Current
foldback limits MOSFET heat dissipation during short-circuit
conditions. Output overvoltage protection circuitry protects
the controller until V
OUT
returns to normal.
Figure 1. High Effi ciency Dual 12V/5V Step-Down Converter
, LTC and LT 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.
FEATURES
APPLICATIONS
n
Telecom Systems
n
Automotive Systems
n
Battery-Operated Digital Devices
n
Wide Output Voltage Range: 0.8V ≤ V
OUT
≤ 14V
n
Out-of-Phase Controllers Reduce Required Input
Capacitance and Power Supply Induced Noise
n
OPTI-LOOP
®
Compensation Minimizes C
OUT
n
±
1% Output Voltage Accuracy
n
Power Good Output Voltage Monitor
n
Phase-Lockable Fixed Frequency 250kHz to 550kHz
n
Dual N-Channel MOSFET Synchronous Drive
n
Wide V
IN
Range: 4V to 36V 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
Selectable Constant Frequency or Burst Mode
®
Operation
n
Small 28-Lead SSOP Package
+
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
LTC3727A-1
PLLIN
LTC3727A-1
2
3727a1fa
PIN CONFIGURATION ABSOLUTE MAXIMUM RATINGS
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
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 150°C
Lead Temperature (Soldering, 10 sec) .................. 300°C
(Note 1)
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
T
JMAX
= 125°C, θ
JA
= 95°C/W
ORDER INFORMATION
LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE
LTC3727AEG-1#PBF LTC3727AEG-1#TRPBF LTC3727AEG-1 28-Lead Plastic SSOP –40°C to 85°C
LTC3727AIG-1#PBF LTC3727AIG-1#TRPBF LTC3727AIG-1 28-Lead Plastic SSOP –40°C to 85°C
LEAD BASED FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE
LTC3727AEG-1 LTC3727AEG-1#TR LTC3727AEG-1 28-Lead Plastic SSOP –40°C to 85°C
LTC3727AIG-1 LTC3727AIG-1#TR LTC3727AIG-1 28-Lead Plastic SSOP –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/
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Main Control Loops
V
OSENSE1, 2
Regulated Feedback Voltage (Note 4); I
TH1, 2
Voltage = 1.2V
l
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
V
LOADREG
Output Voltage Load Regulation (Note 4)
Measured in Servo Loop; ΔI
TH
Voltage = 1.2V to 0.7V
Measured in Servo Loop; ΔI
TH
Voltage = 1.2V to 2.0V
l
l
0.1
–0.1
0.5
–0.5
%
%
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.
LTC3727A-1
3
3727a1fa
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
g
m1, 2
Transconductance Amplifi er g
m
I
TH1, 2
= 1.2V; Sink/Source 5μA (Note 4) 1.3 mmho
g
mGBW1, 2
Transconductance Amplifi er GBW I
TH1, 2
= 1.2V (Note 4) 3 MHz
I
Q
Input DC Supply Current
Normal Mode
Shutdown
(Note 5)
V
IN
= 15V, EXTV
CC
Tied to V
OUT1
, V
OUT1
= 8.5V
V
RUN/SS1, 2
= 0V
670
20 35
μA
μA
V
FCB
Forced Continuous Threshold
l
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)
Threshold
Measured at FCB pin 6.8 7.3 V
UVLO Undervoltage Lockout V
IN
Ramping Down
l
3.5 4 V
V
OVL
Feedback Overvoltage Lockout Measured at V
OSENSE1, 2
l
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
SENSE(MAX)
Maximum Current Sense Threshold V
OSENSE1, 2
= 0.7V, V
SENSE1
–
, 2
–
= 12V
l
105 135 165 mV
TG1, 2 t
r
TG1, 2 t
f
TG Transition Time:
Rise Time
Fall Time
(Note 6)
C
LOAD
= 3300pF
C
LOAD
= 3300pF
50
50
90
90
ns
ns
BG1, 2 t
r
BG1, 2 t
f
BG Transition Time:
Rise Time
Fall Time
(Note 6)
C
LOAD
= 3300pF
C
LOAD
= 3300pF
40
40
90
80
ns
ns
TG/BG t
1D
Top Gate Off to Bottom Gate On Delay
Synchronous Switch-On Delay Time
C
LOAD
= 3300pF Each Driver 90 ns
BG/TG t
2D
Bottom Gate Off to Top Gate On Delay
Top Switch-On Delay Time
C
LOAD
= 3300pF Each Driver 90 ns
t
ON(MIN)
Minimum On-Time Tested with a Square Wave (Note 7) 120 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
l
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
R
PLLIN
PLLIN Input Resistance 100 kΩ
I
PLLFLTR
Phase Detector Output Current
Sinking Capability
Sourcing Capability
f
PLLIN
< f
OSC
f
PLLIN
> f
OSC
–15
15
μA
μA
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LTC3727AIG-1#TRPBF

Mfr. #:
Buy LTC3727AIG-1#TRPBF
Manufacturer:
Analog Devices / Linear Technology
Description:
Switching Voltage Regulators Dual, 2-Phase Synchronous Controller w/ up to 14V Output
Lifecycle:
New from this manufacturer.
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