regulator controller that drives an all N-channel synchro-
nous power MOSFET stage. A constant-frequency current
mode architecture allows a phase-lockable frequency of
up to 650kHz.
The 30μA 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
LTC3834 features a precision 0.8V reference and a power
good output indicator. The 4V to 36V input supply range
encompasses a wide range of battery chemistries.
The TRACK/SS pin ramps the output voltage during
start-up. Current foldback limits MOSFET heat dissipa-
tion during short-circuit conditions. A reduced feature set
version of the part (LTC3834-1) is available in a smaller,
lower pin count package.
Comparison of LTC3834 and LTC3834-1
CLKOUT/
PHASMD
Yes
No
Wide Output Voltage Range: 0.8V ≤ V
OUT
≤ 10V
Low Operating Quiescent Current: 30μA
OPTI-LOOP
®
Compensation Minimizes C
OUT
±1%
Output Voltage Accuracy
Wide V
IN
Range: 4V to 36V
Phase-Lockable Fixed Frequency 140kHz to 650kHz
Dual N-Channel MOSFET Synchronous Drive
Very Low Dropout Operation: 99% Duty Cycle
Adjustable Output Voltage Soft-Start or Tracking
Output Current Foldback Limiting
Power Good Output Voltage Monitor
Clock Output for PolyPhase
®
Applications
Output Overvoltage Protection
Low Shutdown I
Q
: 4μA
Internal LDO Powers Gate Drive from V
IN
or V
OUT
Selectable Continuous, Pulse Skipping or
Burst Mode
®
Operation at Light Loads
Small 20-Lead TSSOP or 4mm
×
5mm QFN Package
APPLICATIONS
n
n
n
n
PART #
LTC3834
LTC3834-1
EXTV
CC
Yes
No
PGOOD
Yes
No
PACKAGES
FE20/4mm
×
5mm QFN
GN16/3mm
×
5mm DFN
Automotive Systems
Telecom Systems
Battery-Operated Digital Devices
Distributed DC Power Systems
L,
LT, LTC, LTM, Burst Mode, PolyPhase 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 5408150, 5481178, 5705919, 5929620, 6304066,
6498466, 6580258, 6611131.
TYPICAL APPLICATION
High Efficiency Synchronous Step-Down Converter
CLKOUT
PLLLPF
RUN
0.01μF
PGOOD
TRACK/SS
I
TH
560pF
54.2k
150pF
SGND
68.1k
PLLIN/MODE
V
FB
215k
SENSE
–
SENSE
+
PGND
INTV
CC
EXTV
CC
BG
4.7μF
LTC3834
BOOST
SW
TG
0.22μF
3.3μH
0.012Ω
V
OUT
3.3V
5A
150μF
V
IN
10μF
V
IN
4V TO 36V
100
90
80
70
EFFICIENCY (%)
60
50
40
30
20
10
0
0.000001
10000
1000
POWER LOSS (mW)
100
10
1
0.1
0.0001
0.01
OUTPUT CURRENT (A)
1
3834 TA01b
3834 TA01
3834fb
1
LTC3834
ABSOLUTE MAXIMUM RATINGS
(Note 1)
Input Supply Voltage (V
IN
) ......................... 36V to –0.3V
Topside Driver Voltage (BOOST) ................ 42V to –0.3V
Switch Voltage (SW) ..................................... 36V to –5V
INTV
CC
, (BOOST-SW), CLKOUT, PGOOD .. 8.5V to –0.3V
RUN, TRACK/SS ......................................... 7V to –0.3V
SENSE
+
, SENSE
–
Voltages ........................ 11V to –0.3V
PLLIN/MODE, PHASMD, PLLLPF ......... INTV
CC
to –0.3V
EXTV
CC
...................................................... 10V to –0.3V
I
TH
, V
FB
Voltages ...................................... 2.7V to –0.3V
Peak Output Current <10μs (TG, BG) ..........................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)
FE Package ....................................................... 300°C
PIN CONFIGURATION
TOP VIEW
PHASMD
TOP VIEW
CLKOUT
PLLLPF
I
TH
TRACKS/SS
V
FB
SGND
PGND
BG
INTV
CC
1
2
3
4
5
6
7
8
9
21
20 PHASMD
19 PLLIN/MODE
18 PGOOD
17 SENSE
+
16 SENSE
–
15 RUN
14 BOOST
13 TG
12 SW
INTV
CC
EXTV
CC
V
IN
SW
11 V
IN
7
8
9 10
I
TH
1
TRACK/SS 2
V
FB
3
SGND 4
PGND 5
BG 6
21
CLKOUT
PLLLPF
PLLIN/MODE
16 PGOOD
15 SENSE
+
14 SENSE
–
13 RUN
12 BOOST
11 TG
20 19 18 17
EXTV
CC
10
FE PACKAGE
20-LEAD PLASTIC TSSOP
T
JMAX
= 125°C,
θ
JA
= 35°C/W
EXPOSED PAD (PIN 21) IS SGND, MUST BE SOLDERED TO PCB
UFD PACKAGE
20-PIN (4mm 5mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JA
= 37°C/W
EXPOSED PAD (PIN 21) IS SGND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
LTC3834EFE#PBF
LTC3834IFE#PBF
LTC3834EUFD#PBF
LTC3834IUFD#PBF
TAPE AND REEL
LTC3834EFE#TRPBF
LTC3834IFE#TRPBF
LTC3834EUFD#TRPBF
LTC3834IUFD#TRPBF
PART MARKING*
LTC3834FE
LTC3834FE
3834
3834
PACKAGE DESCRIPTION
20-Lead Plastic TSSOP
20-Lead Plastic TSSOP
20-Lead (4mm
×
5mm) Plastic QFN
20-Lead (4mm
×
5mm) Plastic QFN
TEMPERATURE RANGE
–40°C to 85°C (Note 2)
–40°C to 85°C
–40°C to 85°C (Note 2)
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Consult LTC Marketing for information on non-standard lead based finish parts.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/
3834fb
2
LTC3834
ELECTRICAL CHARACTERISTICS
SYMBOL
V
FB
I
VFB
V
REFLNREG
V
LOADREG
PARAMETER
Regulated Feedback Voltage
Feedback Current
Reference Voltage Line Regulation
Output Voltage Load Regulation
Main Control Loops
(Note 4); I
TH
Voltage = 1.2V
(Note 4)
V
IN
= 4V to 30V (Note 4)
(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
I
TH
= 1.2V; Sink/Source 5μA (Note 4)
(Note 5)
RUN = 5V, V
FB
= 0.83V (No Load)
V
RUN
= 0V
V
IN
Ramping Down
Measured at V
FB
Relative to Regulated V
FB
V
SENSE–
= V
SENSE+
= 0V
In Dropout
V
TRACK
= 0V
V
RUN
Rising
V
FB
= 0.7V, V
SENSE–
= 3.3V
(Note 6)
C
LOAD
= 3300pF
C
LOAD
= 3300pF
(Note 6)
C
LOAD
= 3300pF
C
LOAD
= 3300pF
l
l
l
l
l
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 12V, V
RUN
= 5V unless otherwise noted.
CONDITIONS
MIN
0.792
TYP
0.800
–5
0.002
0.1
–0.1
0.5
30
4
3.7
8
98
0.85
0.5
85
10
–220
99.4
1.1
0.7
100
50
50
40
40
70
70
200
5
7.2
4.5
5.25
0.2
7.5
0.2
4.7
0.2
V
PLLLPF
= No Connect
V
PLLLPF
= 0V
V
PLLLPF
= INTV
CC
PLLIN/MODE = External Clock; V
PLLLPF
= 0V
650
360
220
475
400
250
530
115
800
–5
5
440
280
580
140
5.5
1.0
7.8
1.0
1.45
0.9
115
90
90
90
80
50
10
4
12
MAX
0.808
–50
0.02
0.5
–0.5
UNITS
V
nA
%/V
%
%
mmho
μA
μA
V
%
μA
%
μA
V
mV
ns
ns
ns
ns
ns
ns
ns
V
%
V
%
V
V
kHz
kHz
kHz
kHz
kHz
μA
μA
3834fb
g
m
I
Q
Transconductance Amplifier g
m
Input DC Supply Current
Sleep Mode
Shutdown
Undervoltage Lockout
Feedback Overvoltage Lockout
Sense Pins Total Source Current
Maximum Duty Factor
Soft-Start Charge Current
RUN Pin ON Threshold
Maximum Current Sense Threshold
TG Transition Time:
Rise Time
Fall Time
BG Transition Time:
Rise Time
Fall Time
UVLO
V
OVL
I
SENSE
DF
MAX
I
TRACK/SS
V
RUN
ON
V
SENSE(MAX)
TG t
r
TG t
f
BG t
r
BG t
f
TG/BG t
1D
BG/TG t
2D
t
ON(MIN)
V
INTVCCVIN
V
LDOVIN
V
INTVCCEXT
V
LDOEXT
V
EXTVCC
V
LDOHYS
f
NOM
f
LOW
f
HIGH
f
SYNCMIN
f
SYNCMAX
I
PLLLPF
Top Gate Off to Bottom Gate On Delay C
LOAD
= 3300pF
Synchronous Switch-On Delay Time
Bottom Gate Off to Top Gate On Delay C
LOAD
= 3300pF
Top Switch-On Delay Time
Minimum On-Time
Internal V
CC
Voltage
INTV
CC
Load Regulation
Internal V
CC
Voltage
INTV
CC
Load Regulation
EXTV
CC
Switchover Voltage
EXTV
CC
Hysteresis
Nominal Frequency
Lowest Frequency
Highest Frequency
Minimum Synchronizable Frequency
Phase Detector Output Current
Sinking Capability
Sourcing Capability
(Note 7)
8.5V < V
IN
< 30V, V
EXTVCC
= 0V
I
CC
= 0mA to 20mA, V
EXTVCC
= 0V
V
EXTVCC
= 8.5V
I
CC
= 0mA to 20mA, V
EXTVCC
= 8.5V
EXTV
CC
Ramping Positive
INTV
CC
Linear Regulator
Oscillator and Phase-Locked Loop
Maximum Synchronizable Frequency PLLIN/MODE = External Clock; V
PLLLPF
= 2V
f
PLLIN/MODE
< f
OSC
f
PLLIN/MODE
> f
OSC
3
LTC3834
ELECTRICAL CHARACTERISTICS
SYMBOL
PGOOD Output
V
PGL
I
PGOOD
V
PG
PGOOD Voltage Low
PGOOD Leakage Current
PGOOD Trip Level
I
PGOOD
= 2mA
V
PGOOD
= 5V
V
FB
with Respect to Set Regulated Voltage
V
FB
Ramping Negative
V
FB
Ramping Positive
–12
8
–10
10
0.1
0.3
±1
–8
12
V
μA
%
%
PARAMETER
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 12V, V
RUN
= 5V unless otherwise noted.
CONDITIONS
MIN
TYP
MAX
UNITS
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2:
The LTC3834E is guaranteed to meet performance specifications
from 0°C to 85°C. Specifications over the –40°C to 85°C operating
temperature range are assured by design, characterization and correlation
with statistical process controls. The LTC3834I is guaranteed to meet
performance specifications over the –40°C to 85°C operating temperature
range.
Note 3:
T
J
is calculated from the ambient temperature T
A
and power
dissipation P
D
according to the following formulas:
LTC3834FE: T
J
= T
A
+ (P
D
• 35°C/W)
LTC3834UFD: T
J
= T
A
+ (P
D
• 37°C/W)
Note 4:
The LTC3834 is tested in a feedback loop that servos V
ITH
to a
specified voltage and measures the resultant V
FB
.
Note 5:
Dynamic supply current is higher due to the gate charge being
delivered at the switching frequency. See Applications Information.
Note 6:
Rise and fall times are measured using 10% and 90% levels. Delay
times are measured using 50% levels.
Note 7:
The minimum on-time condition is specified for an inductor
peak-to-peak ripple current ≥40% of I
MAX
(see Minimum On-Time
Considerations in the Applications Information section).
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
