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LTC3827EG-1#PBF

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P30P31-P32
LTC3827-1
1
38271fe
TYPICAL APPLICATION
FEATURES
APPLICATIONS
DESCRIPTION
Low I
Q
, Dual, 2-Phase
Synchronous Step-Down Controller
The LTC
®
3827-1 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 a phase-lockable fre-
quency of up to 650kHz. Power loss and noise due to the
ESR of the input capacitor ESR are minimized by operating
the two controller output stages out of phase.
The 80µA no-load quiescent current extends operating
life in battery-powered systems. OPTI-LOOP compensa-
tion allows the transient response to be optimized over
a wide range of output capacitance and ESR values. The
LTC3827-1 features a precision 0.8V reference and a power
good output indicator. A wide 4V to 36V input supply range
encompasses all battery chemistries.
Independent TRACK/SS pins for each controller ramp the
output voltage during start-up. Current foldback limits
MOSFET heat dissipation during short-circuit conditions.
The PLLIN/MODE pin selects among Burst Mode opera-
tion, pulse-skipping mode, or continuous inductor cur-
rent mode at light loads. For a leadless package version
(5mm × 5mm QFN) with additional features, see the
LTC3827 data sheet.
High Effi ciency Dual 8.5V/3.3V Step-Down Converter
n
Wide Output Voltage Range: 0.8V ≤ V
OUT
≤ 10V
n
Low Operating I
Q
: 80μA (One Channel On)
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
Wide V
IN
Range: 4V to 36V Operation
n
Phase-Lockable Fixed Frequency 140kHz to 650kHz
n
Selectable Continuous, Pulse-Skipping or Low Ripple
Burst Mode
®
Operation at Light Loads
n
Dual N-Channel MOSFET Synchronous Drive
n
Very Low Dropout Operation: 99% Duty Cycle
n
Adjustable Output Voltage Soft-Start or Tracking
n
Output Current Foldback Limiting
n
Power Good Output Voltage Monitor
n
Output Overvoltage Protection
n
Low Shutdown I
Q
: 8µA
n
Internal LDO Powers Gate Drive from V
IN
or V
OUT
n
Small 28-Lead SSOP Package
n
Automotive Systems
n
Battery-Operated Digital Devices
n
Distributed DC Power Systems
L, LT, LTC, LTM, 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, 5408150,
6580258, 6304066, 5705919.
Effi ciency and Power Loss
vs Load Current
+
4.7µF
0.1µF
62.5k
3.3µH
220pF
150µF
1µF
22µF
50V
0.015Ω
20k
15k
V
OUT1
3.3V
5A
150µF
0.1µF
192.5k
7.2µH
220pF
0.015Ω
20k
15k
V
OUT2
8.5V
3.5A
TG1 TG2
BOOST1 BOOST2
SW1 SW2
BG1 BG2
SGND
PGND
SENSE1
+
SENSE2
+
SENSE1
–
SENSE2
–
V
FB1
V
FB2
I
TH1
I
TH2
V
IN
INTV
CC
TRACK/SS1 TRACK/SS2
V
IN
4V TO 36V
38271 TA01
0.1µF
0.1µF
LTC3827-1
LOAD CURRENT (mA)
EFFICIENCY (%)
POWER LOSS (mW)
0.01 0.1 1 10 100 1000 10000
38271 TA01b
0.001
1
10
1000
100
0.1
100000
10000
40
50
60
70
80
30
20
10
0
90
100
POWER LOSS
EFFICIENCY
V
IN
= 12V; V
OUT
= 3.3V
FIGURE 13 CIRCUIT
LTC3827-1
2
38271fe
PACKAGE/ORDER INFORMATION ABSOLUTE MAXIMUM RATINGS
Input Supply Voltage (V
IN
) .........................36V to –0.3V
Topside Driver Voltages
BOOST1, BOOST2 .................................. 42V to –0.3V
Switch Voltage (SW1, SW2) ......................... 36V to –5V
(BOOST1-SW1), (BOOST2-SW2) ............. 8.5V to –0.3V
RUN1, RUN2 ............................................... 7V to –0.3V
SENSE1
+
, SENSE2
+
, SENSE1
–
,
SENSE2
–
Voltages ..................................... 11V to –0.3V
PLLIN/MODE, PLLLPF, TRACK/SS1, TRACK/SS2
Voltages ............................................... INTV
CC
to –0.3V
EXTV
CC
...................................................... 10V to –0.3V
I
TH1,
I
TH2
, V
FB1
, V
FB2
Voltages .................. 2.7V to –0.3V
PGOOD1 Voltage ....................................... 8.5V 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
I
TH1
V
FB1
SENSE1
+
SENSE1
–
PLLLPF
PLLIN/MODE
SGND
RUN1
RUN2
SENSE2
–
SENSE2
+
V
FB2
I
TH2
TRACK/SS2
TRACK/SS1
PGOOD1
TG1
SW1
BOOST1
BG1
V
IN
PGND
EXTV
CC
INTV
CC
BG2
BOOST2
SW2
TG2
T
JMAX
= 125°C, θ
JA
= 95°C/W
ORDER INFORMATION
LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE
LTC3827EG-1#PBF LTC3827EG-1#TRPBF 3827EG-1 28-Lead Plastic SSOP –40°C to 85°C
LTC3827IG-1#PBF LTC3827IG-1#TRPBF 3827IG-1 28-Lead Plastic SSOP –40°C to 85°C
LEAD BASED FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE
LTC3827EG-1 LTC3827EG-1#TR 3827EG-1 28-Lead Plastic SSOP –40°C to 85°C
LTC3827IG-1 LTC3827IG-1#TR 3827IG-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/
LTC3827-1
3
38271fe
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
= 12V, V
RUN/SS1, 2
= 5V unless otherwise noted.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Main Control Loops
V
FB1, 2
Regulated Feedback Voltage (Note 4) I
TH1, 2
Voltage = 1.2V
●
0.792 0.800 0.808 V
I
VFB1, 2
Feedback Current (Note 4) –5 –50 nA
V
REFLNREG
Reference Voltage Line Regulation V
IN
= 4V 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 2V
●
●
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) 1.55 mmho
I
Q
Input DC Supply Current
Sleep Mode (Channel 1 On)
Sleep Mode (Channel 2 On)
Shutdown
Sleep Mode (Both Channels)
(Note 5)
RUN1 = 5V, RUN2 = 0V, V
FB1
= 0.83V (No Load)
RUN1 = 0V, RUN2 = 5V, V
FB2
= 0.83V (No Load)
V
RUN1, 2
= 0V
RUN1,2 = 5V, V
FB1
= V
FB2
= 0.83V
80
80
8
115
125
125
20
160
µA
µA
µA
µA
UVLO Undervoltage Lockout V
IN
Ramping Down
●
3.5 4 V
V
OVL
Feedback Overvoltage Lockout Measured at V
FB1, 2
, Relative to Regulated V
FB1, 2
81012 %
I
SENSE
Sense Pins Total Source Current (Each Channel) V
SENSE1
–
, 2
–
= V
SENSE1
+
, 2
+
= 0V –660 µA
DF
MAX
Maximum Duty Factor In Dropout 98 99.4 %
I
TRACK/SS1, 2
Soft-Start Charge Current V
TRACK1, 2
= 0V 0.75 1.0 1.35 µA
V
RUN1, 2
ON RUN Pin ON Threshold V
RUN1,
V
RUN2
Rising 0.5 0.7 0.9 V
V
SENSE(MAX)
Maximum Current Sense Threshold V
FB1, 2
= 0.7V, V
SENSE1
–
, 2
– = 3.3V
V
FB1, 2
= 0.7V, V
SENSE1
–
, 2
– = 3.3V
●
90
80
100
100
110
115
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
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 70 ns
BG/TG t
2D
Bottom Gate Off to Top Gate On Delay
Top Switch-On Delay Time
C
LOAD
= 3300pF Each Driver 70 ns
t
ON(MIN)
Minimum On-Time (Note 7) 180 ns
INTV
CC
Linear Regulator
V
INTVCCVIN
Internal V
CC
Voltage 8.5V < V
IN
< 30V, V
EXTVCC
= 0V 5.0 5.25 5.5 V
V
LDOVIN
INTV
CC
Load Regulation I
CC
= 0mA to 20mA, V
EXTVCC
= 0V 0.2 1.0 %
V
INTVCCEXT
Internal V
CC
Voltage V
EXTVCC
= 8.5V 7.2 7.5 7.8 V
V
LDOEXT
INTV
CC
Load Regulation I
CC
= 0mA to 20mA, V
EXTVCC
= 8.5V 0.2 1.0 %
V
EXTVCC
EXTV
CC
Switchover Voltage 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
PLLLPF
= Floating; PLLIN/MODE = DC Voltage 360 400 440 kHz
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LTC3827EG-1#PBF

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Manufacturer:
Analog Devices / Linear Technology
Description:
Switching Voltage Regulators L IQ, 2x, 2-PhSync Buck Cntr
Lifecycle:
New from this manufacturer.
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