LTC3355.pdf 데이터시트 (총 20 페이지) - 파일 다운로드 LTC3355 데이타시트 다운로드

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FEATURES
nn VIN Voltage Range: 3V to 20V
nn VOUT Voltage Range: 2.7V to 5V
nn 1A Current Mode Buck Main Regulator
nn 5A Boost Backup Regulator Powered from Single
Supercapacitor
nn Boost Regulator Operates Down to 0.5V for
Maximum Utilization of Supercapacitor Energy
nn Programmable Supercapacitor Charge Current to
1A with Overvoltage Protection
nn Charger Supports Single Cell CC/CV Battery Charging
nn Programmable VIN Current Limit
nn Programmable Boost Current Limit
nn VIN Power Fail Indicator
nn VCAP Power Good Indicator
nn VOUT Power On Reset Output
nn Compact 20-Lead 4mm × 4mm QFN Package
APPLICATIONS
nn Ride-Through “Dying Gasp” Supplies
nn Power Meters/Industrial Alarms/Solid State Drives
LTC3355
20V 1A Buck DC/DC with
Integrated SCAP Charger
and Backup Regulator
DESCRIPTION
The LTC®3355 is a complete input power interrupt ride-
through DC/DC system. The part charges a supercapacitor
while delivering load current to VOUT, and uses energy from
the supercapacitor to provide continuous VOUT backup
power when VIN power is lost. The LTC3355 contains a
nonsynchronous constant frequency current mode mono-
lithic 1A buck switching regulator to provide a 2.7V to 5V
regulated output voltage from an input supply of up to 20V.
A 1A programmable CC/CV linear charger charges the
supercapacitor from VOUT. When the VIN supply drops
below the PFI threshold, the devices’s constant frequency
nonsynchronous current mode 5A boost switching
regulator delivers power from the supercapacitor to VOUT.
A thermal regulation loop maximizes charge current while
limiting the die temperature to 110°C. The IC has boost,
charger and VIN programmablecurrent limits. The LTC3355
is available in a 20-lead 4mm × 4mm QFN surface mount
package.
L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks
of Linear Technology Corporation. All other trademarks are the property of their respective
owners.
TYPICAL APPLICATION
Supercapacitor Charger and Ride-Through Power Supply
VIN
12V 10µF
0.091Ω
10µF
2.49M
200k
5 VIN
1µF
6 VINM5
4 VINS
1 PFI
SW1 7
PFO BUCK VOUT 15
1A
FB 2
10 PFOB
13 RSTB
9 CPGOOD
8 EN_CHG
3 MODE
INTVCC
18
LTC3355
BOOST
ICHG
12
VCAP 14
SW2
16
17
CFB 11
IBSTPKVCBST 19
20
1µF 60.4k 200k
6.8µH
4.7pF 402k
100k
3.3µH
665k
154k
220pF
3355 TA01a
332k
VOUT
4V
47µF 1A (MAX)
2.4V
SCAP
1F TO 50F
Backup Operation
14
CAPACITOR = 3F
12 IVOUT = 0.125A
10
VIN
8
6
4 VOUT
2 VCAP
0
0 5 10 15 20
TIME (SECONDS)
3355 TA01b
For more information www.linear.com/LTC3355
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LTC3355
ABSOLUTE MAXIMUM RATINGS
(Note 1)
VIN, VINS, VINM5.........................................................22V
VIN ±VINS................................................................... 0.1V
VSW1........................................................... –0.4V to 22V
VSW2............................................................. –0.4V to 6V
VOUT, INTVCC, PFOB, RSTB,
CPGOOD, VCAP.............................................. –0.3V to 6V
PFI, EN_CHG, MODE, FB............................... –0.3V to 6V
CFB.............................................–0.3V to INTVCC + 0.3V
ICPGOOD, IPFOB, IRSTB.................................................1mA
Operating Junction Temperature Range
(Notes 2, 3)............................................. –40°C to 125°C
Storage Temperature Range................... –65°C to 150°C
PIN CONFIGURATION
TOP VIEW
PFI 1
FB 2
MODE 3
VINS 4
VIN 5
20 19 18 17 16
15 VOUT
14 VCAP
21
GND
13 RSTB
12 ICHG
11 CFB
6 7 8 9 10
UF PACKAGE
20-LEAD (4mm × 4mm) PLASTIC QFN
TJMAX = 125°C, θJA = 47°C/W
EXPOSED PAD (PIN 21) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
TAPE AND REEL
PART MARKING
PACKAGE DESCRIPTION
LTC3355EUF#PBF
LTC3355EUF#TRPBF
3355
20-Lead (4mm × 4mm) Plastic QFN
LTC3355IUF#PBF
LTC3355IUF#TRPBF
3355
20-Lead (4mm × 4mm) Plastic QFN
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on nonstandard 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/
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
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LTC3355
E LECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at TA = 25°C. VIN = 12V unless otherwise noted. (Note 2)
SYMBOL PARAMETER
CONDITIONS
MIN TYP MAX UNITS
VIN VIN Operating Voltage Range
l3
20
IQ VIN Quiescent Current
VOUT Quiescent Current
Charger Off, Not Switching, VOUT = 3.3V, No l
60
120 215
Load, In Regulation, Supercapacitor Charged l 110 265 420
VFB FB Reference Voltage
l 0.775
0.825
FB Line Regulation
VOUT = 2.7V to 5V
0.1
IFB FB Input Bias Current
–20 20
VVOUT
VOUT Voltage Range
l 2.7
5
VOUT Overvoltage Limit
Buck or Boost Enabled
5.4 5.65 5.95
VOUT Undervoltage Lockout Threshold Boost Enabled
1.8 2 2.2
VINM5
VIN-VINM5
VIN > 7V
4.65
VINTVCC INTVCC Internal Voltage Power Supply
25
VVCAP
VCAP Voltage Range
05
IVCAP
VCAP Current Accuracy
EVNCA_PC=HG2V=, HViOgUhT = 3.3V, IVCAP = 1A
–10
10
V
µA
µA
V
%/V
nA
V
V
V
V
V
V
%
VICHG
RICHG
ICFB
VCFB
VCAP Programmable Current Range
ICHG Reference Voltage
ICHG Set Resistor Range
CFB Input Bias Current
CFB Reference Voltage
CFB Hysteresis
EN_CHG = High
EN_CHG = High
EN_CHG = High
EN_CHG = High
0.1 1
0.78 0.82
60.4 604
–20 20
0.78 0.8 0.82
30
A
V
nA
V
mV
IICL
VINS(CMI)
fSW
CFB Overvoltage Hysteretic Comparator
Switch Point
VIN Input Current Limit
VINS Common Mode Range
Switching Frequency
Foldback Frequency (Buck Only)
CFB Rising
CFB Falling
VVIINNSS--VVIINN
to
to
Disable
Disable
Charger
Buck
FB ≥ 0.5V
FB ≤ 0.3V
VCFBV+C0FB.035
37 43
42 50
3.0 20
0.75 1 1.25
100
V
V
mV
mV
V
MHz
kHz
VPFI PFI Falling Threshold
PFI Hysteresis
l 0.775 0.8 0.825
17
V
mV
IPFI PFI Leakage Current
1A Buck Regulator
–20 20 nA
ISW1 SW1 Peak Current
PWM Mode (Note 5)
Burst Mode® (Note 5)
1.3 1.65
0.5
2
A
A
tSS
DC Max
Soft-Start Time
Maximum Duty Cycle
FB = 0V
1000
100
µs
%
RPMOS
ILEAKP
PMOS On-Resistance
PMOS Leakage Current
Buck Disabled
0.5
–2
1
2
Ω
µA
For more information www.linear.com/LTC3355
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LTC3355
E LECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at TA = 25°C. VIN = 12V unless otherwise noted. (Note 2)
SYMBOL PARAMETER
CONDITIONS
MIN TYP MAX UNITS
5A Boost Regulator
IVOUT
VOUT Quiescent Current
VOUT = 3.3V, No Load, In Regulation, No
Switching, Burst Mode
l 80
160 280
µA
ISW2 SW2 Peak Current
RNMOS
ILEAKN
DC Max
NMOS On-Resistance
NMOS Leakage Current
Boost Maximum Duty Cycle
RIBSTPK = 200k, PWM Mode
RIBSTPK = 200k, Burst Mode
Boost Disabled
4.5 5 5.5
1.5
70
–5 5
88 92 98
A
A
µA
%
VSBOOST Boost Input Supply Voltage Range
Boost Minimum Input Supply
AV Boost Error Amplifier Voltage Gain
gm Boost Error Amplifier Transconductance
VIBSTPK IBSTPK Reference Voltage
RIBSTPK IBSTPK Set Resistor Range
Logic (MODE, EN_CHG, CPGOOD, RSTB, PFOB)
VOUT(MAX) = 4V
(Note 5)
0.75 5
0.5
850
27
0.775
0.825
200 1000
V
V
V/V
μS
V
VIL
VIH
IIL, IIH
VOL
IOH
Input Low Logic Voltage
Input High Logic Voltage
Input Low/High Current
Output Logic Low Voltage
Logic High Leakage Current
CPGOOD Rising Threshold
CPGOOD Hysteresis
RSTB Falling Threshold
RSTB Hysteresis
RSTB Delay
MODE, EN_CHG
MODE, EN_CHG
MODE, EN_CHG
PFOB, CPGOOD, RSTB; Sink 100µA
PFOB, CPGOOD, RSTB; 5V
VCAP as a % of Final Target
VCAP as a % of Final Value
VOUT as a % of Final Target
VOUT as a % of Final Value
0.4
1.2
-1 1
50
1
90 92.5 95
2.5
90 92.5 95
2.5
250
V
V
µA
mV
µA
%
%
%
%
ms
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 LTC3355 is tested under pulsed load conditions such that
TJ ≈ TA. The LTC3355E 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
LTC3355I is guaranteed over the –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. The junction temperature
(TJ, in °C) is calculated from the ambient temperature (TA, in °C) and
power dissipation (PD, in Watts) according to the formula:
TJ = TA + (PD θJA)
where θJA = 47°C/W for the UF package.
Note 3: The LTC3355 has a thermal regulation loop that limits the
maximum junction temperature to 110°C by limiting the charger current.
Note 4: The current limit features of this part are intended to protect the
IC from short-term or intermittent fault conditions. Continuous operation
above the maximum specified pin current may result in device degradation
or failure.
Note 5: Guaranteed by design and/or correlation to static test.
Note 6: The LTC3355 has a thermal shutdown that will shut down the part
when the die temperature reaches 155°C.
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LTC3355
TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C unless otherwise noted
Buck Efficiency
100
90
80
70
60
50
40
30 VOUT = 4V
20
MODE = HIGH
VIN = 18V
10
VIN = 12V
VIN = 6V
0
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
LOAD CURRENT (A)
3355 G01
Maximum Boost Load Current
1.2 VOUT = 4V
1.0
0.8
0.6
0.4
0.2
0
0.75 1.25 1.75 2.25 2.75 3.25 3.75
VCAP (V)
3355 G04
Buck Frequency
vs Feedback Voltage
1000
900
800
700
600
500
400
300
200
100
0
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5
FB (V)
3355 G07
Boost Efficiency
100
90
80
70
60
50
40
30 VCAP = 2.4V
20
MODE = HIGH
VOUT = 3.3V
10
VOUT = 4V
VOUT = 5V
0
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
LOAD CURRENT (A)
3355 G02
Buck Switch Voltage Drop
700
600
500
400
300
200
100
0
0 100 200 300 400 500 600 700 800 900 1000
SWITCH CURRENT (mA)
3355 G05
Typical Minimum Buck Input
Voltage (VOUT = 3.3V)
4.6 VOUT = 3.3V
4.4
L = 6.8µH
INPUT CURRENT SET RESISTOR = 0.05Ω
4.2
4.0
3.8
3.6
3.4
3.2
3.0
1
10 100
VOUT LOAD CURRENT (mA)
1000
3355 G08
For more information www.linear.com/LTC3355
Maximum Buck Load Current
1.20
1.00
0.80
0.60
0.40
0.20 VOUT = 4V
L = 6.8µH
INPUT CURRENT SET RESISTOR = 0Ω
0
4 6 8 10 12 14 16 18
VIN (V)
20
3355 G03
Oscillator Frequency
vs Temperature
1200
1150
1100
1050
1000
950
900
850
800
–50 –25
0 25 50 75
TEMPERATURE (°C)
100 125
3355 G06
Typical Minimum Buck Input
Voltage (VOUT = 5V)
6.3 VOUT = 5V
6.1 L = 6.8µH
INPUT CURRENT SET RESISTOR = 0.05Ω
5.9
5.7
5.5
5.3
5.1
4.9
4.7
4.5
1
10 100
VOUT LOAD CURRENT (mA)
1000
3355 G09
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