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LTC3707IGN-SYNC#TRPBF

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P30P31-P32
LTC3707-SYNC
1
3707sfa
TYPICAL APPLICATION
DESCRIPTION
High Effi ciency, 2-Phase
Synchronous Step-Down Switching Regulator
The LTC
®
3707-SYNC 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 300kHz. 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. The precision 0.8V reference and power good
output indicator are compatible with future microprocessor
generations, and a wide 4.5V to 28V (30V maximum) input
supply range encompasses all battery chemistries.
A RUN/SS pin for each controller provides both soft-
start and optional timed, short-circuit shutdown. Current
foldback limits MOSFET 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 operation, constant
frequency mode and continuous inductor current mode
or regulate a secondary winding. The IC 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
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. Burst Mode
and OPTI-LOOP are registered trademarks of Linear Technology Corporation. Protected by U.S.
Patents including 5481178, 5705919, 5929620, 6144194, 6177787, 6304066, 6580258.
FEATURES
APPLICATIONS
n
Notebook and Palmtop Computers, PDAs
n
Telecom Systems
n
Portable Instruments
n
Battery-Operated Digital Devices
n
DC Power Distribution Systems
n
180° Phased Controllers Reduce Required Input
Capacitance and Power Supply Induced Noise
n
OPTI-LOOP
®
Compensation Minimizes C
OUT
n
Dual N-Channel MOSFET Synchronous Drive
n
±1.5% Output Voltage Accuracy
n
Power Good Output Voltage Monitor
n
Phase-Lockable Fixed Frequency 150kHz to 300kHz
n
Wide V
IN
Range: 4.5V to 28V Operation
n
Very Low Dropout Operation: 99% Duty Cycle
n
Adjustable Soft-Start Current Ramping
n
Foldback Output Current Limiting
n
Latched Short-Circuit Shutdown with Defeat Option
n
Output Overvoltage Protection
n
Remote Output Voltage Sense
n
Low Shutdown I
Q
: 20μA
n
5V and 3.3V Standby Regulators
n
Small 28-Lead Narrow SSOP Package (0.150˝ Wide)
n
Selectable Constant Frequency, Burst Mode
®
or
PWM Operation
+
4.7μF
D3
D4
D1
M2
M1
C
B1
, 0.1μF
R2
105k
1%
1000pF
L1
6.3μH
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
D2
M4
M3
C
B2
, 0.1μF
R4
63.4k
1%
L2
6.3μH
C
C2
220pF
1000pF
+
C
OUT
56mμF
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, M3, M4: FDS6680A
3707 F01
C
SS1
0.1μF
C
SS2
0.1μF
LTC3707-SYNC
PLLINf
IN
LTC3707-SYNC
2
3707sfa
PIN CONFIGURATION ABSOLUTE MAXIMUM RATINGS
Input Supply Voltage (V
IN
) ......................... 30V to –0.3V
Top Side Driver Voltages
(BOOST1, BOOST2) ................................... 36V to –0.3V
Switch Voltage (SW1, SW2) ......................... 30V to –5V
INTV
CC
, EXTV
CC
, RUN/SS1, RUN/SS2, (BOOST1-SW1),
(BOOST2-SW2), PGOOD .............................. 7V to –0.3V
SENSE1
+
, SENSE2
+
, SENSE1
–
,
SENSE2
–
Voltages .........................(1.1)INTV
CC
to –0.3V
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 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
GN 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
= 80°C/W
ORDER INFORMATION
LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE
LTC3707EGN-SYNC#PBF
LTC3707EGN-SYNC#TRPBF
LTC3707EGN-SYNC 28-Lead Plastic SSOP –40°C to 85°C
LTC3707IGN-SYNC#PBF
LTC3707IGN-SYNC#TRPBF
LTC3707IGN-SYNC 28-Lead Plastic SSOP –40°C to 85°C
LEAD BASED FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE
LTC3707EGN-SYNC LTC3707EGN-SYNC#TR LTC3707EGN-SYNC 28-Lead Plastic SSOP –40°C to 85°C
LTC3707IGN-SYNC LTC3707IGN-SYNC#TR LTC3707IGN-SYNC 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
0.788 0.800 0.812 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
%
%
g
m1, 2
Transconductance Amplifi er g
m
I
TH1, 2
= 1.2V; Sink/Source 5μA; (Note 4) 1.3 mmho
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.
LTC3707-SYNC
3
3707sfa
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
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
= 5V
V
RUN/SS1, 2
= 0V, V
STBYMD
= Open
350
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 –0.1 μA
V
BINHIBIT
Burst Inhibit (Constant Frequency)
Threshold
Measured at FCB pin 4.3 4.8 V
UVLO Undervoltage Lockout V
IN
Ramping Down
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 –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
RUN/SS1, 2
LT RUN/SS Pin Latchoff Arming Threshold V
RUN/SS1
, V
RUN/SS2
Rising from 3V 4.1 4.75 V
I
SCL1, 2
RUN/SS Discharge Current Soft Short Condition V
OSENSE1, 2
= 0.5V;
V
RUN/SS1, 2
= 4.5V
0.5 2 4 μA
I
SDLHO
Shutdown Latch Disable Current V
OSENSE1, 2
= 0.5V 1.6 5 μA
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
l
65
62
75
75
85
88
mV
mV
TG1, 2 t
r
TG1, 2 t
f
TG Transition Time:
Rise Time
Fall Time
(Note 6)
C
LOAD
= 3300pF
C
LOAD
= 3300pF
60
60
110
110
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
50
50
110
100
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 7) 180 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
l
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 190 220 250 kHz
f
LOW
Lowest Frequency V
PLLFLTR
= 0V 120 140 160 kHz
f
HIGH
Highest Frequency V
PLLFLTR
≥ 2.4V 280 310 360 kHz
R
PLLIN
PLLIN Input Resistance 50 kΩ
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LTC3707IGN-SYNC#TRPBF

Mfr. #:
Buy LTC3707IGN-SYNC#TRPBF
Manufacturer:
Analog Devices / Linear Technology
Description:
Switching Voltage Regulators High Efficiency, 2-Phase Synchronous Step-Down Switching Regulator
Lifecycle:
New from this manufacturer.
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