switching regulator controller targeted for high power
applications. It drives all N-channel power MOSFETs. The
controlled on-time valley current mode architecture allows
for both fast transient response and constant frequency
switching in steady-state operation, independent of V
IN
,
V
OUT
and load current.
Differential output voltage sensing along with a precision
internal reference combine to offer ±0.67% output regula-
tion and the ability to correct for up to ±500mV variations
in the output terminals due to line losses. The operating
frequency can be programmed from 200kHz to 2MHz with
an external resistor and can be synchronized to an external
clock for noise and EMI sensitive applications.
Very low t
ON
and t
OFF
times allow for near 0% and near
100% duty cycles, respectively. Programmable soft-start or
output voltage tracking is available. Safety features include
output overvoltage protection, programmable current limit
with foldback, and a power good output signal.
L,
LT, LTC, LTM, OPTI-LOOP PolyPhase, µModule, Linear Technology and the Linear logo
,
are registered trademarks and Hot Swap, No R
SENSE
and UltraFast are trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
Protected by U.S. Patents, including 5481178, 5487554, 6580258, 6304066, 6476589,
6774611.
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Wide V
IN
Range: 4.5V to 38V
V
OUT
Range: 0.6V to 5.5V
Output Accuracy: ±0.25% at 25°C and ±0.67%
over Temperature
Differential Output Sensing Allowing Up to 500mV
Line Loss
Fast Load Transient Response
t
ON(MIN)
= 20ns, t
OFF(MIN)
= 90ns
Controlled On-Time Valley Current Mode
Architecture
Frequency Programmable from 200kHz to 2MHz
and Synchronizable to External Clock
R
SENSE
or Inductor DCR Current Sensing
Overvoltage Protection and Current Limit Foldback
Power Good Output Voltage Monitor
Output Tracking or Adjustable Soft-Start
External V
CC
Input for Bypassing Internal LDO
20-Pin QFN (3mm
×
4mm) and TSSOP Packages
APPLICATIONS
n
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Distributed Power Systems
Point-of-Load Converters
Computing Systems
Datacomm Systems
TYPICAL APPLICATION
1.5V, 20A, 300kHz High Current Step-Down Converter
INTV
CC
V
RNG
100k
V
IN
V
OUT
SENSE
–
SENSE
+
TG
SW
0.1µF
INTV
CC
4.7µF
3.24k
180µF
0.1µF
V
OUT
1.5V
20A
330µF
×2
10k
BG
PGND
V
OSNS+
V
OSNS–
EFFICIENCY (%)
80
70
60
50
40
3833 TA01a
V
IN
4.5V TO 14V
Efficiency
100
90
PULSE-SKIPPING
MODE
PGOOD
RUN
0.1µF
470pF
LTC3833
0.47µH
15k
TRACK/SS
10k
137k
I
TH
RT
EXTV
CC
SGND
300kHz
MODE/PLLIN
BOOST
INTV
CC
FORCED
CONTINUOUS
MODE
V
IN
= 12V
V
OUT
= 1.5V
0.1
1
10
LOAD CURRENT (A)
100
3833 TA01b
3833f
1
LTC3833
ABSOLUTE MAXIMUM RATINGS
(Note 1)
V
IN
Voltage ................................................ –0.3V to 40V
BOOST Voltage .......................................... –0.3V to 46V
SW Voltage ................................................... –5V to 40V
INTV
CC
, EXTV
CC
, (BOOST-SW), PGOOD, RUN,
MODE/PLLIN, V
RNG
Voltages ....................... –0.3V to 6V
V
OUT
, SENSE
+
, SENSE
–
Voltages.................. –0.6V to 6V
V
OSNS+
, V
OSNS –
Voltages ........ –0.6V to (INTV
CC
+ 0.3V)
RT, ITH Voltages ..................... –0.3V to (INTV
CC
+ 0.3V)
TRACK/SS Voltages ..................................... –0.3V to 5V
Operating Junction Temperature Range
(Notes 2, 3, 4) ........................................ –40°C to 125°C
Storage Temperature Range .................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec)
FE Package ....................................................... 300°C
PIN CONFIGURATION
TOP VIEW
SENSE
–
SENSE
+
PGOOD
V
OUT
TOP VIEW
PGOOD
16 BOOST
15 TG
21
SGND
14 SW
13 BG
12 PGND
11 INTV
CC
7
RUN
8
EXTV
CC
9 10
MODE/PLLIN
V
IN
SENSE
+
SENSE
–
V
OUT
V
OSNS
–
20 19 18 17
V
OSNS–
1
V
OSNS+
2
TRACK/SS 3
ITH 4
V
RNG
5
RT 6
1
2
3
4
5
6
7
8
9
21
SGND
20 BOOST
19 TG
18 SW
17 BG
16 PGND
15 INTV
CC
14 V
IN
13 MODE/PLLIN
12 EXTV
CC
11 RUN
V
OSNS+
TRACK/SS
ITH
V
RNG
RT 10
UDC PACKAGE
20-LEAD (3mm
×
4mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JA
= 43°C/W
EXPOSED PAD (PIN 21) IS SGND, MUST BE SOLDERED TO PCB
FE PACKAGE
20-LEAD PLASTIC TSSOP
T
JMAX
= 125°C,
θ
JA
= 38°C/W
EXPOSED PAD (PIN 21) IS SGND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
LTC3833EUDC#PBF
LTC3833IUDC#PBF
LTC3833EFE#PBF
LTC3833IFE#PBF
TAPE AND REEL
LTC3833EUDC#TRPBF
LTC3833IUDC#TRPBF
LTC3833EFE#TRPBF
LTC3833IFE#TRPBF
PART MARKING*
LFGT
LFGT
LTC3833FE
LTC3833FE
PACKAGE DESCRIPTION
20-Lead (3mm
×
4mm) Plastic QFN
20-Lead (3mm
×
4mm) Plastic QFN
20-Lead Plastic TSSOP
20-Lead Plastic TSSOP
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
–40°C to 125°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/
3833f
2
LTC3833
ELECTRICAL CHARACTERISTICS
SYMBOL
General
V
IN
V
OUT
I
Q
t
ON(MIN)
t
OFF(MIN)
V
REG
Input Voltage Operating Range
Output Voltage Operating Range
Input DC Supply Current
Normal
Shutdown Supply Current
Minimum On-Time
Minimum Off-Time
Regulated Differential Feedback Voltage
(V
OSNS+
– V
OSNS–
)
Regulated Differential Feedback Voltage
Over Line, Load and Common Mode
(V
OSNS+
– V
OSNS–
)
g
m(EA)
I
VOSNS+
I
VOSNS–
V
SENSE(MAX)
V
SENSE(MIN)
V
SENSE(CM)
I
SENSE
Error Amplifier Transconductance
V
OSNS+
Input Bias Current
V
OSNS–
Input Bias Current
Valley Current Sense Threshold,
V
SENSE+
– V
SENSE–,
Peak Current = Valley + Ripple
Minimum Current Sense Threshold,
V
SENSE+
– V
SENSE–
, Forced Continuous
Mode
SENSE
+
, SENSE
–
Voltage Range
(Common Mode)
SENSE
+
, SENSE
–
Input Bias Current
ITH = 1.2V (Note 5)
T
A
= 25°C
T
A
= 0°C to 85°C
T
A
= –40°C to 125°C
V
IN
= 4.5V to 38V, ITH = 0.5V to 1.9V,
V
OSNS–
= ±500mV (Note 5)
T
A
= 0°C to 85°C
T
A
= –40°C to 125°C
ITH = 1.2V (Note 5)
V
FB
= 0.6V
V
FB
= 0.6V
V
RNG
= 2V, V
FB
= 0.57V
V
RNG
= 0V, V
FB
= 0.57V
V
RNG
= INTV
CC
, V
FB
= 0.57V
V
RNG
= 2V, V
FB
= 0.63V
V
RNG
= 0V, V
FB
= 0.63V
V
RNG
= INTV
CC
, V
FB
= 0.63V
Referenced to Signal Ground (SGND)
V
SENSE(CM)
= 0.6V
V
SENSE(CM)
= 5V
V
RUN
Rising
V
TRACK/SS
= 0V
INTV
CC
Falling
INTV
CC
Rising
R
T
= 205k
R
T
= 80.6k
R
T
= 18.2k
l
l
l
l
l
l
l
The
l
denotes the specifications which apply over the full operating junction
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 15V, V
FB
= V
OSNS+
– V
OSNS–
, unless otherwise noted. (Note 4)
PARAMETER
CONDITIONS
MIN
4.5
0.6
MODE/PLLIN = INTV
CC
RUN = 0V
V
IN
= 38V, V
OUT
= 0.6V
2
15
20
90
TYP
MAX
38
5.5
4
25
UNITS
V
V
mA
µA
ns
ns
Output Sensing
0.5985
0.596
0.594
0.6
0.6
0.6
0.6015
0.604
0.606
V
V
V
l
l
l
l
l
0.594
0.591
1.4
0.6
0.6
1.7
±5
–35
0.606
0.609
2
±25
–50
120
38
61
V
V
mS
nA
µA
mV
mV
mV
mV
mV
mV
Current Sensing
80
22
39
100
30
50
–50
–15
–25
–0.5
±5
1
1.1
1.2
70
1.0
3.4
3.65
4.2
175
450
1800
2
0.5
200
500
2000
4.0
4.5
225
550
2200
5.5
±50
4
1.3
V
nA
µA
V
mV
µA
V
V
kHz
kHz
kHz
V
V
Start-Up and Shutdown
V
RUN(TH)
V
RUN(HYS)
I
SS
UVLO
LOCK
RUN Pin On Threshold
RUN Pin Hysteresis
Soft-Start Charging Current
INTV
CC
Undervoltage Lockout
UVLO
RELEASE
INTV
CC
Undervoltage Lockout Release
Switching Frequency and Clock Synchronization
f
Free Running Switching Frequency
V
CLK(IH)
V
CLK(IL)
Clock Input High Level into MODE/PLLIN
Clock Input Low Level into MODE/PLLIN
3833f
3
LTC3833
ELECTRICAL CHARACTERISTICS
SYMBOL
Gate Drivers
R
TG(HI)
R
TG(LO)
R
BG(HI)
R
BG(LO)
t
DLY(OFF)
t
DLY(ON)
TG Driver Pull-Up On-Resistance
TG Driver Pull-Down On-Resistance
BG Driver Pull-Up On-Resistance
BG Driver Pull-Down On-Resistance
Top Gate Off to Bottom Gate On
Delay Time
Bottom Gate Off to Top Gate On
Delay Time
Internal V
CC
Voltage
Internal V
CC
Load Regulation
EXTV
CC
Switchover Voltage
EXTV
CC
Switchover Hysteresis
EXTV
CC
Voltage Drop
PGOOD Upper Threshold
PGOOD Lower Threshold
PGOOD Hysteresis
PGOOD Low Voltage
Delay from OV/UV Fault to PGOOD Falling
Delay from OV/UV Recovery to PGOOD
Rising
V
EXTVCC
= 5V, I
CC
= 50mA
V
FB
Rising (with Respect to Regulated
Feedback Voltage V
REG
)
V
FB
Falling (with Respect to Regulated
Feedback Voltage V
REG
)
V
FB
Returning
I
PGOOD
= 5mA
5
–10
TG High
TG Low
BG High
BG Low
(Note 6)
(Note 6)
2.5
1.2
2.5
0.8
20
15
Ω
Ω
Ω
Ω
ns
ns
PARAMETER
The
l
denotes the specifications which apply over the full operating junction
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 15V, V
FB
= V
OSNS+
– V
OSNS–
, unless otherwise noted. (Note 4)
CONDITIONS
MIN
TYP
MAX
UNITS
Internal V
CC
Regulator and External V
CC
INTV
CC
INTV
CC
(%)
EXTV
CC(TH)
EXTV
CC(HYS)
∆EXTV
CC
PGOOD Output
PGD
OV
PGD
UV
PGD
HYS
V
PGD(LO)
t
PGD(FALL)
t
PGD(RISE)
7.5
–7.5
2
0.15
20
10
0.4
10
–5
%
%
%
V
µs
µs
6V < V
IN
< 38V
I
CC
= 0mA to 50mA
EXTV
CC
Rising
4.4
5.1
5.3
–1
4.6
200
200
5.55
–2
4.75
V
%
V
mV
mV
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 junction temperature (T
J
in °C) is calculated from the ambient
temperature (T
A
in °C) and power dissipation (P
D
in Watts) as follows:
T
J
= T
A
+ (P
D
•
θ
JA
)
where
θ
JA
(in °C/W) is the package thermal impedance provided in the Pin
Configuration section for the corresponding package.
Note 3:
This IC includes overtemperature protection that is intended to
protect the device during momentary overload conditions. The maximum
rated junction temperature will be exceeded when this protection is active.
Continuous operation above the specified absolute maximum operating
junction temperature may impair device reliability or permanently damage
the device.
Note 4:
The LTC3833 is tested under pulsed loading conditions such
that T
J
≈ T
A
. The LTC3833E is guaranteed to meet specifications from
0°C to 85°C junction temperature; specifications over the –40°C to
125°C operating junction temperature range are assured by design,
characterization and correlation with statistical process controls. The
LTC3833I is guaranteed to meet specifications over the full –40°C to 125°C
operating junction temperature range. Note that the maximum ambient
temperature consistent with these specifications is determined by specific
operating conditions in conjunction with board layout, the rated package
thermal impedance and other environmental factors.
Note 5:
The LTC3833 is tested in a feedback loop that adjusts
V
FB
= V
OSNS+
– V
OSNS–
to achieve a specified error amplifier output voltage
(on ITH pin). The specification at 85°C is not tested in production. This
specification is assured by design, characterization and correlation to
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