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LTC3805EDD#TRPBF

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P20
LTC3805
1
3805fg
Features
applications
Description
Adjustable Frequency
Current Mode Flyback
DC/DC Controller
The LT C
®
3805 is a current mode controller for flyback
DC/DC converters designed to drive an N-channel MOSFET
in high input and output voltage converter applications.
Operating frequency and slope compensation can be
programmed by external resistors. Programmable overcur-
rent sensing protects the converter from short-circuits.
Soft-start can be programmed using an external capacitor
and the soft-start capacitor also programs an automatic
restart feature.
The LTC3805 provides ±1.5% output voltage accuracy
and consumes only 360µA of quiescent current during
normal operation and only 40µA during micropower start-
up. Using a 9.5V internal shunt regulator, the LTC3805
can be powered from a high V
IN
through a resistor or it
can be powered directly from a low impedance DC voltage
of 9V or less.
The LTC3805 is available in the 10-lead MSOP package
and the 3mm × 3mm DFN package.
36V – 72V to 5V/2A Nonisolated Flyback Converter
n
V
IN
and V
OUT
Limited Only by External Components
n
Adjustable Slope Compensation
n
Adjustable Overcurrent Protection with Automatic
Restart
n
Adjustable Operating Frequency (70kHz to 700kHz)
with One External Resistor
n
Synchronizable to an External Clock
n
±1.5% Reference Accuracy
n
Current Mode Operation for Excellent Line and Load
Transient Response
n
RUN Pin with Precision Threshold and Adjustable
Hysteresis
n
Programmable Soft-Start with One External Capacitor
n
Low Quiescent Current: 360µA
n
Small 10-Lead MSOP and 3mm × 3mm DFN
n
Telecom Power Supplies
n
42V and 12V Automotive Power Supplies
n
Isolated Electronic Equipment
LTC3805
GND
I
TH
RUN
GATE
OC
I
SENSE
SSFLT
FS FB
V
CC
118k
3k
68mΩ
2.2µF
×2
22µF
SYNC
1.33k
8.66k
221k 100k
V
IN
36V TO
72V
V
OUT
5V
AT 2A
13.7k
71.5k
100µF
× 2
3805 TA01a
0.1µF
20k
470pF
LOAD CURRENT (A)
0.01
0
EFFICIENCY (%)
POWER LOSS (W)
20
30
40
50
60
70
0.1
1
3805 TA01b
80
90
100 10
1
0.1
10
10
V
IN
= 48V
LOSS
EFFICIENCY
Efficiency and Power Loss
vs Load Current; V
O
= 5V
typical application
L,LT , LT C , LTM , Burst Mode, Linear Technology and the Linear logo are registered trademarks,
No R
SENSE
and ThinSOT are trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
LTC3805
2
3805fg
absolute MaxiMuM ratings
V
CC
to GND
Low Impedance Source ........................ –0.3V to 8.8V
Current Fed ........................................25mA into V
CC
*
SYNC ........................................................... –0.3V to 6V
SSFLT........................................................... –0.3V to 5V
FB, I
TH
, FS ................................................. –0.3V to 3.5V
RUN ........................................................... –0.3V to 18V
(Note 1)
TOP VIEW
DD PACKAGE
10-LEAD (3mm × 3mm) PLASTIC DFN
10
11
9
6
7
8
4
5
3
2
1
GATE
V
CC
OC
I
SENSE
SYNC
SSFLT
I
TH
FB
RUN
FS
T
JMAX
= 125°C, θ
JA
= 45°C/W
EXPOSED PAD (PIN 11) IS GND, MUST BE CONNECTED TO GND
1
2
3
4
5
SSFLT
I
TH
FB
RUN
FS
10
9
8
7
6
GATE
V
CC
OC
I
SENSE
SYNC
TOP VIEW
MSE PACKAGE
10-LEAD PLASTIC MSOP
11
T
JMAX
= 150°C, θ
JA
= 45°C/W
EXPOSED PAD (PIN 11) IS GND, MUST BE CONNECTED TO GND
OC, I
SENSE
.................................................... –0.3V to 1V
Operating Junction Temperature Range
(Notes 2, 3) ............................................ –55°C to 150°C
Storage Temperature Range .................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec)
MSE Package .................................................... 300°C
*LTC3805 internal clamp circuit regulates V
CC
voltage to 9.5V
orDer inForMation
LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LTC3805EDD#PBF LTC3805EDD#TRPBF LCJM
10-Lead (3mm × 3mm) Plastic DFN
–40°C to 85°C
LTC3805IDD#PBF LTC3805IDD#TRPBF LCJM
10-Lead (3mm × 3mm) Plastic DFN
–40°C to 125°C
LTC3805EMSE#PBF LTC3805EMSE#TRPBF LTCJK 10-Lead Plastic MSOP –40°C to 85°C
LTC3805IMSE#PBF LTC3805IMSE#TRPBF LTCJK 10-Lead Plastic MSOP –40°C to 125°C
LTC3805HMSE#PBF LTC3805HMSE#TRPBF LTCJK 10-Lead Plastic MSOP –40°C to 150°C
LTC3805MPMSE#PBF LTC3805MPMSE#TRPBF LTCJK 10-Lead Plastic MSOP –55°C to 150°C
LEAD BASED FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE
LTC3805EDD LTC3805EDD#TR LCJM
10-Lead (3mm × 3mm) Plastic DFN
–40°C to 85°C
LTC3805IDD LTC3805IDD#TR LCJM
10-Lead (3mm × 3mm) Plastic DFN
–40°C to 125°C
LTC3805EMSE LTC3805EMSE#TR LTCJK 10-Lead Plastic MSOP –40°C to 85°C
LTC3805IMSE LTC3805IMSE#TR LTCJK 10-Lead Plastic MSOP –40°C to 125°C
LTC3805HMSE LTC3805HMSE#TR LTCJK 10-Lead Plastic MSOP –40°C to 150°C
LTC3805MPMSE LTC3805MPMSE#TR LTCJK 10-Lead Plastic MSOP –55°C to 150°C
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/
pin conFiguration
LTC3805
3
3805fg
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
TURNON
V
CC
Turn-On Voltage
l
7.75 8.4 9 V
V
TURNOFF
V
CC
Turn-Off Voltage
l
3.75 3.95 4.15 V
V
HYST
V
CC
Hysteresis 4.5 V
V
CLAMP1mA
V
CC
Shunt Regulator Voltage V
CC
Sinking 1mA, V
RUN
= 0
l
8.8 9.25 9.65 V
V
CLAMP25mA
V
CC
Shunt Regulator Voltage V
CC
Sinking 25mA, V
RUN
= 0
l
8.9 9.5 9.9 V
I
CC
Input DC Supply Current Normal Operation (f
OSC
= 200kHz)
(Note 4)
360 µA
V
RUN
< V
RUNON
or V
CC
< V
TURNON
– 100mV
(Micropower Start-Up)
l
40 90 µA
V
RUNON
RUN Turn-On Voltage V
CC
Sinking 1mA
l
1.122 1.207 1.292 V
V
RUNOFF
RUN Turn-Off Voltage V
CC
Sinking 1mA
l
1.092 1.170 1.248 V
I
RUN(HYST)
RUN Hysteresis Current
l
4 5 5.8 µA
V
FB
Regulated Feedback Voltage 0°C ≤ T
J
≤ 85°C (E-Grade) (Note 5)
–40°C ≤ T
J
≤ 85°C (E-Grade) (Note 5)
–40°C ≤ T
J
≤ 125°C (I-Grade) (Note 5)
–40°C ≤ T
J
≤ 150°C (H-Grade) (Note 5)
–55°C ≤ T
J
≤ 150°C (MP-Grade)
l
l
l
l
0.788
0.780
0.780
0.770
0.770
0.800
0.800
0.800
0.800
0.800
0.812
0.812
0.812
0.820
0.820
V
V
V
V
V
I
FB
V
FB
Input Current V
ITH
= 1.3V (Note 5) 20 nA
g
m
Error Amplifier Transconductance I
TH
Pin Load = ±5µA (Note 5) 333 µA/V
∆V
O(LINE)
Output Voltage Line Regulation V
TURNOFF
< V
CC
< V
CLAMP1mA
(Note 5) 0.05 mV/V
∆V
O(LOAD)
Output Voltage Load Regulation I
TH
Sinking 5µA (Note 5)
I
TH
Sourcing 5µA (Note 5)
3
3
mV/µA
mV/µA
f
OSC
Oscillator Frequency R
FS
= 350k 70 kHz
R
FS
= 36k 700 kHz
DC
ON(MIN)
Minimum Switch-On Duty Cycle f
OSC
= 200kHz 6 9 %
DC
ON(MAX)
Maximum Switch-On Duty Cycle f
OSC
= 200kHz 70 80 95 %
f
SYNC
As a Function of f
OSC
70kHz < f
OSC
< 700kHz,
70kHz < f
SYNC
< 700kHz
67 133 %
V
SYNC
Minimum SYNC Amplitude 2.9 V
I
SS
Soft-Start Current –6 µA
I
FTO
Fault Timeout Current 2 µA
t
SS(INT)
Internal Soft-Start Time No External Capacitor on SSFLT 1.8 ms
t
FTO(INT)
Internal Fault Timeout No External Capacitor on SSFLT 4.5 ms
t
RISE
Gate Drive Rise Time C
LOAD
= 3000pF 30 ns
t
FALL
Gate Drive Fall Time C
LOAD
= 3000pF 30 ns
V
I(MAX)
Peak Current Sense Voltage R
SL
= 0 (Note 6)
l
85 100 115 mV
I
SL(MAX)
Peak Slope Compensation Output
Current
(Note 7) 10 µA
V
OCT
Overcurrent Threshold R
OC
= 0 (Note 8)
l
85 100 115 mV
I
OC
Overcurrent Threshold Adjust Current 10 µA
electrical characteristics
The l denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at T
A
= 25°C, V
CC
= 8V, unless otherwise noted (Note 2).
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P20

LTC3805EDD#TRPBF

Mfr. #:
Buy LTC3805EDD#TRPBF
Manufacturer:
Analog Devices / Linear Technology
Description:
Switching Voltage Regulators Programmable Frequency Current Mode Flyback Controller
Lifecycle:
New from this manufacturer.
Delivery:
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