regulator controller that can directly step-down voltages
from up to 60V, making it ideal for telecom and automo-
tive applications. The LTC3810-5 uses a constant on-time
valley current control architecture to deliver very low duty
cycles with accurate cycle-by-cycle current limit, without
requiring a sense resistor.
A precise internal reference provides 0.5% DC accuracy. A
high bandwidth (25MHz) error amplifier provides very fast
line and load transient response. Large 1Ω gate drivers
allow the LTC3810-5 to drive multiple MOSFETs for higher
current applications. The operating frequency is selected
by an external resistor and is compensated for variations
in V
IN
and can also be synchronized to an external clock
for switching-noise sensitive applications. A shutdown
pin allows the LTC3810-5 to be turned off, reducing the
supply current to 240µA.
Integrated bias control generates gate drive power from
the input supply during start-up or when an output short-
circuit occurs, with the addition of a small external SOT23
MOSFET. When in regulation, power is derived from the
output for higher efficiency.
High Voltage Operation: Up to 60V
Large 1Ω Gate Drivers
No Current Sense Resistor Required
Dual N-Channel MOSFET Synchronous Drive
Extremely Fast Transient Response
±0.5% 0.8V Voltage Reference
Programmable Output Voltage Tracking/Soft-Start
Generates 5.5V Driver Supply from Input Supply
Synchronizable to External Clock
Selectable Pulse Skip Mode Operation
Power Good Output Voltage Monitor
Adjustable On-Time/Frequency: t
ON(MIN)
< 100ns
Adjustable Cycle-by-Cycle Current Limit
Programmable Undervoltage Lockout
Output Overvoltage Protection
5mm
×
5mm QFN Package
applicaTions
n
n
n
48V Telecom and Base Station Power Supplies
Networking Equipment, Servers
Automotive and Industrial Control Systems
L,
LT, LTC, LTM, Linear Technology, the Linear logo and No R
SENSE
are registered trademarks
of Linear Technology Corporation. All other trademarks are the property of their respective
owners. Protected by U.S. Patents including 5481178, 5847554, 6304066, 6476589, 6580258,
6677210, 6774611.
Typical applicaTion
High Efficiency High Voltage Step-Down Converter
274k
I
ON
PGOOD
V
RNG
1000pF
NDRV
BOOST
TG
SW
EXTV
CC
DRV
CC
INTV
CC
SENSE
+
BG
SGND
SENSE
–
BGRTN
Si7450DP
MBR1100
14k
Si7450DP
100k
ZXMN10A07F
EFFICIENCY (%)
Efficiency vs Load Current
100
V
IN
= 24V
95
V
IN
= 42V
+
V
IN
13V TO 60V
22µF
LTC3810-5
0.1µF
10µH
V
OUT
12V/6A
MODE/SYNC
SS/TRACK
SHDN
90
+
47pF
5pF
I
TH
200k
V
FB
270µF
85
0
1
2
3
4
LOAD CURRENT (A)
5
6
38105 TA01b
1µF
1k
38105 TA01
38105fd
1
LTC3810-5
absoluTe MaxiMuM raTings
(Note 1)
pin conFiguraTion
TOP VIEW
BOOST
SW
24 SENSE
+
23 NC
22 NC
33
21 NC
20 SENSE
–
19 BGRTN
18 BG
17 DRV
CC
9 10 11 12 13 14 15 16
EXTV
CC
SS/TRACK
INTV
CC
NC
NC
SHDN
UVIN
NDRV
I
ON
NC
NC
NC
NC
TG
Supply Voltages
INTV
CC
, DRV
CC
...................................... –0.3V to 14V
(DRV
CC
– BGRTN), (BOOST – SW) ........ –0.3V to 14V
BOOST (Continuous) .............................. –0.3V to 85V
BOOST (≤400ms) .................................. –0.3V to 95V
BGRTN ........................................................ –5V to 0V
EXTV
CC
.................................................. –0.3V to 15V
(EXTV
CC
– INTV
CC
) .................................. –12V to 12V
(NDRV – INTV
CC
) Voltage .......................... –0.3V to 10V
SW, SENSE
+
Voltage (Continuous) .................–1V to 70V
SW, SENSE
+
Voltage (400ms) ........................–1V to 80V
I
ON
Voltage (Continuous) ............................ –0.3V to 70V
I
ON
Voltage (400ms)................................... –0.3V to 80V
SS/TRACK Voltage....................................... –0.3V to 5V
PGOOD Voltage ............................................ –0.3V to 7V
V
RNG
, V
ON
, MODE/SYNC,
SHDN,
UVIN Voltages ............................................ –0.3V to 14V
PLL/LPF, FB Voltages ................................ –0.3V to 2.7V
TG, BG, INTV
CC
, EXTV
CC
RMS Currents ................50mA
Operating Junction Temperature Range (Notes 2, 3, 7)
LTC3810E-5 ....................................... –40°C to 125°C
LTC3810I-5 ........................................ –40°C to 125°C
LTC3810H-5 ....................................... –40°C to 150°C
Storage Temperature Range .................. –65°C to 125°C
32 31 30 29 28 27 26 25
NC 1
V
ON
2
V
RNG
3
PGOOD 4
MODE/SYNC 5
I
TH
6
V
FB
7
PLL/LPF 8
UH PACKAGE
32-LEAD (5mm
×
5mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JA
= 34°C/W
EXPOSED PAD (PIN 33) IS SGND, MUST BE SOLDERED TO PCB
orDer inForMaTion
LEAD FREE FINISH
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC3810EUH-5#PBF
LTC3810EUH-5#TRPBF
38105
–40°C to 125°C
32-Lead (5mm
×
5mm) Plastic QFN
LTC3810IUH-5#PBF
LTC3810IUH-5#TRPBF
38105
–40°C to 125°C
32-Lead (5mm
×
5mm) Plastic QFN
LEAD BASED FINISH
TAPE AND REEL
PART MARKING
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC3810EUH-5
LTC3810EUH-5#TR
38105
–40°C to 125°C
32-Lead (5mm
×
5mm) Plastic QFN
LTC3810IUH-5
LTC3810IUH-5#TR
38105
–40°C to 125°C
32-Lead (5mm
×
5mm) Plastic QFN
LTC3810HUH-5
LTC3810HUH-5#TR
38105
–40°C to 150°C
32-Lead (5mm
×
5mm) Plastic QFN
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
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/
38105fd
2
LTC3810-5
elecTrical characTerisTics
SYMBOL
Main Control Loop
INTV
CC
I
Q
I
BOOST
V
FB
PARAMETER
INTV
CC
Supply Voltage
INTV
CC
Supply Current
INTV
CC
Shutdown Current
BOOST Supply Current
Feedback Voltage
The
l
denotes specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C (Note 2), INTV
CC
= DRV
CC
= V
BOOST
= V
ON
= V
RNG
=
SHDN
= UV
IN
=
V
EXTVCC
= V
NDRV
= 5V, V
MODE/SYNC
= V
SENSE
+
= V
SENSE
–
= V
BGRTN
= V
SW
= 0V, unless otherwise specified.
CONDITIONS
l
MIN
4.35
TYP
MAX
14
6
600
400
5
0.804
0.806
0.806
0.808
0.812
0.02
384
120
260
UNITS
V
mA
µA
µA
µA
V
V
V
V
V
%/V
mV
mV
mV
mV
mV
mV
nA
dB
MHz
V
µA
V
µA
V
V
V
V
V
V
V
µs
ns
ns
ns
µs
µs
µA
µA
A
Ω
A
Ω
38105fd
DV
FB,LINE
V
SENSE(MAX)
V
SENSE(MIN)
I
VFB
A
VOL
(EA)
f
U
V
MODE/SYNC
I
MODE/SYNC
V
SHDN
I
SHDN
V
UVIN
V
VCCUV
Feedback Voltage Line Regulation
Maximum Current Sense Threshold
Minimum Current Sense Threshold
Feedback Current
Error Amplifier DC Open Loop Gain
Error Amp Unity-Gain Crossover
Frequency
MODE/SYNC Threshold
MODE/SYNC Current
Shutdown Threshold
SHDN
Pin Input Current
UVIN Undervoltage Lockout
INTV
CC
Undervoltage Lockout
Linear Regulator Mode
External Supply Mode
Trickle-Charge Mode
SHDN
> 1.5V (Notes 4, 5)
SHDN
= 0V
SHDN
> 1.5V (Note 5)
SHDN
= 0V
(Note 4)
0°C to 85°C
–40°C to 85°C
–40°C to 125°C (I-Grade)
–40°C to 150°C (H-Grade)
5V < INTV
CC
< 14V (Note 4)
V
RNG
= 2V, V
FB
= 0.76V
V
RNG
= 0V, V
FB
= 0.76V
V
RNG
= INTV
CC
, V
FB
= 0.76V
V
RNG
= 2V, V
FB
= 0.84V
V
RNG
= 0V, V
FB
= 0.84V
V
RNG
= INTV
CC
, V
FB
= 0.84V
V
FB
= 0.8V
(Note 6)
V
MODE/SYNC
Rising
MODE/SYNC = 5V
l
l
l
l
l
0.796
0.794
0.792
0.792
0.792
256
70
170
3
240
270
0
0.800
0.800
0.800
0.800
0.800
0.002
320
95
215
–300
–85
–200
20
100
25
0.8
0
1.5
0
0.89
0.80
0.10
4.2
4.2
9
3.7
1.85
605
250
150
65
0.75
1.2
UVIN Rising
UVIN Falling
Hysteresis
INTV
CC
Rising, I
NDRV
= 100µA
INTV
CC
Rising, NDRV = INTV
CC
= EXTV
CC
INTV
CC
Rising, NDRV = INTV
CC
, EXTV
CC
= 0
INTV
CC
Falling
I
ON
= 100µA
I
ON
= 300µA
I
ON
= 2000µA
l
l
0.86
0.78
0.07
4.05
4.05
8.70
0.85
1
2
1
0.92
0.82
0.12
4.35
4.35
9.30
l
l
l
Oscillator and Phase-Locked Loop
On-Time
t
ON
t
ON(MIN)
t
OFF(MIN)
t
ON(PLL)
I
PLL/LPF
Driver
I
BG,PEAK
R
BG,SINK
I
TG,PEAK
R
TG,SINK
Minimum On-Time
Minimum Off-Time
t
ON
Modulation Range by PLL
Down Modulation
Up Modulation
Phase Detector Output Current
Sinking Capability
Sourcing Capability
BG Driver Peak Source Current
BG Driver Pull-Down R
DS(ON)
TG Driver Peak Source Current
TG Driver Pull-Down R
DS(ON)
1.55
515
2.15
695
100
350
5
1.8
I
ON
= 100µA, V
PLL/LPF
= 0.6V
I
ON
= 100µA, V
PLL/LPF
= 1.8V
f
PLLIN
< f
SW
f
PLLIN
> f
SW
V
BG
= 0V
V
TG
– V
SW
= 0
2.2
0.6
3.6
1.2
15
–25
0.7
0.7
1
1
1
1
1.5
1.5
3
LTC3810-5
The
l
denotes specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C (Note 2), INTV
CC
= DRV
CC
= V
BOOST
= V
ON
= V
RNG
=
SHDN
= UV
IN
=
V
EXTVCC
= V
NDRV
= 5V, V
MODE/SYNC
= V
SENSE
+
= V
SENSE
–
= V
BGRTN
= V
SW
= 0V, unless otherwise specified.
SYMBOL
PGOOD Output
DV
FBOV
DV
FB,HYST
V
PGOOD
I
PGOOD
PG Delay
Tracking
I
SS/TRACK
V
FB,TRACK
V
CC
Regulators
V
EXTVCC
V
INTVCC,1
DV
EXTVCC,1
DV
LOADREG,1
V
INTVCC,2
DV
LOADREG,2
I
NDRV
I
NDRVTO
V
CCSR
I
CCSR
PARAMETER
PGOOD Upper Threshold
PGOOD Lower Threshold
PGOOD Hysterisis
PGOOD Low Voltage
PGOOD Leakage Current
PGOOD Delay
SS/TRACK Source Current
Feedback Voltage at Tracking
CONDITIONS
V
FB
Rising
V
FB
Falling
V
FB
Returning
I
PGOOD
= 5mA
V
PGOOD
= 5V
V
FB
Falling
V
SS/TRACK
> 0.5V
V
TRACK
= 0V, I
TH
= 1.2V (Note 4)
V
TRACK
= 0.5V, I
TH
= 1.2V (Note 4)
0.7
0.48
MIN
7.5
–7.5
TYP
10
–10
1.5
0.3
0
120
1.4
–0.018
0.5
MAX
12.5
–12.5
3
0.6
2
UNITS
%
%
%
V
µA
µs
µA
V
V
elecTrical characTerisTics
2.5
0.52
EXTV
CC
Switchover Voltage
EXTV
CC
Rising
EXTV
CC
Hysterisis
INTV
CC
Voltage from EXTV
CC
V
EXTVCC
- V
INTVCC
at Dropout
INTV
CC
Load Regulation from EXTV
CC
INTV
CC
Voltage from NDRV Regulator
INTV
CC
Load Regulation from NDRV
Current into NDRV Pin
Linear Regulator Timeout Enable
Threshold
Maximum Supply Voltage
Maximum Current into NDRV/INTV
CC
l
6V < V
EXTVCC
< 15V
I
CC
= 20mA, V
EXTVCC
= 5V
I
CC
= 0mA to 20mA, V
EXTVCC
= 10V
Linear Regulator in Operation
I
CC
= 0mA to 20mA, V
EXTVCC
= 0
V
NDRV
– V
INTVCC
= 3V
4.45
0.1
5.2
4.7
0.25
5.5
75
0.01
5.5
0.01
40
270
15
0.4
5.8
150
5.8
60
350
V
V
V
mV
%
V
%
µA
µA
V
mA
5.2
20
210
Trickle Charger Shunt Regulator
Trickle Charger Shunt Regulator,
INTV
CC
≤ 16.7V (Note 8)
10
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 LTC3810-5 is tested under pulsed load conditions such that
T
J
≈ T
A
. The LTC3810E-5 is guaranteed to meet performance specifications
from 0°C to 85°C. Specifications over the –40°C to 125°C operating
junction temperature range are assured by design, characterization and
correlation with statistical process controls. The LTC3810I-5 is guaranteed
to meet performance specifications over the full –40°C to 125°C operating
junction temperature range. The LTC3810H-5 is guaranteed to meet
performance specifications over the full –40°C to 150°C operating junction
temperature range. High junction temperatures degrade operating lifetimes;
operating lifetime is derated for junction temperatures greater than 125°C.
Note 3:
T
J
is calculated from the ambient temperature T
A
and power
dissipation P
D
according to the following formula:
LTC3810-5: T
J
= T
A
+ (P
D
• 34°C/W)
Note 4:
The LTC3810-5 is tested in a feedback loop that servos V
FB
to the
reference voltage with the I
TH
pin forced to a voltage between 1V and 2V.
Note 5:
The dynamic input supply current is higher due to the power
MOSFET gate charging being delivered at the switching frequency
(Q
G
• f
OSC
).
Note 6:
Guaranteed by design. Not subject to test.
Note 7:
This IC includes overtemperature protection that is intended
to protect the device during momentary overload conditions. Junction
temperature will exceed 150°C when overtemperature protection is active.
Continuous operation above the specified maximum operating junction
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