TYPICAL APPLICATION
FEATURES
APPLICATIONS
DESCRIPTION
Converter with 2A Switch, Soft-Start, and Synchronization
The LT ®3580 is a PWM DC/DC converter containing an internal 2A, 42V switch. The LT3580 can be confi gured as either a boost, SEPIC or inverting converter. Capable of generating 12V at 550mA or –12V at 350mA from a 5V input, the LT3580 is ideal for many local power supply designs.
The LT3580 has an adjustable oscillator, set by a resistor from the RT pin to ground. Additionally, the LT3580 can be synchronized to an external clock. The free running or synchronized switching frequency range of the part can be set between 200kHz and 2.5MHz.
The LT3580 also features innovative SHDN pin circuitry that allows for slowly varying input signals and an adjust-able undervoltage lockout function.
Additional features such as frequency foldback and soft-start are integrated. The LT3580 is available in tiny 3mm × 3mm 8-lead DFN and 8-lead MSOP packages.
1.2MHz, 5V to 12V Boost Converter Achieves over 88% Effi ciency
n
2A Internal Power Switch
n Adjustable Switching Frequency n Single Feedback Resistor Sets V OUT n Synchronizable to External Clock n High Gain SHDN Pin Accepts Slowly Varying Input Signals
n Wide Input Voltage Range: 2.5V to 32V n Low V CESAT Switch: 300mV at 1.5A (Typical)n Integrated Soft-Start Function n Easily Confi gurable as a Boost or Inverting Converter n User Confi gurable Undervoltage Lockout (UVLO)n Tiny 8-Lead 3mm × 3mm DFN and 8-Lead MSOP Packages
n
VFD Bias Supplies n TFT-LCD Bias Supplies n GPS Receivers n DSL Modems
n Local Power Supply
Effi ciency and Power Loss
L , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners.
OUT V IN
5V
LOAD CURRENT (mA)
50E F
F I C I E N C Y (%)
POWER LOSS (mW)55657075400953580 TA01b
60200100
500
300600
8085900
20060012004008001000
ABSOLUTE MAXIMUM RATINGS
平面
音响V IN Voltage .................................................–0.3V to 32V SW Voltage ................................................–0.4V to 42V –0.3V to 5V SS and FB Voltage .....................................–0.3V to 2.5V VC Voltage ...................................................–0.3V to 2V SHDN Voltage ............................................–0.3V to 32V(Note 1)
TOP VIEW
DD PACKAGE
8-LEAD (3mm × 3mm) PLASTIC DFN
5
6789
4
321FB VC V IN SW SYNC SS RT SHDN
T JMAX = 125°C, θJA = 43°C/W
EXPOSED PAD (PIN 9) IS GND, MUST BE SOLDERED TO PCB
1234
FB
VC V IN SW
8765SYNC SS RT SHDN
TOP VIEW
9
MS8E PACKAGE 8-LEAD PLASTIC MSOP
T JMAX = 125°C, θJA = 35°C/W TO 40°C/W
EXPOSED PAD (PIN 9) IS GND, MUST BE SOLDERED TO PCB
PIN CONFIGURATION
ORDER INFORMATION
LEAD FREE FINISH TAPE AND REEL PART MARKING*PACKAGE DESCRIPTION TEMPERATURE RANGE LT3580EDD#PBF LT3580EDD#TRPBF LCXY 8-Lead (3mm × 3mm) Plastic DFN –40°C to 125°C LT3580IDD#PBF LT3580IDD#TRPBF LCXY 8-Lead (3mm × 3mm) Plastic DFN –40°C to 125°C LT3580EMS8E#PBF LT3580EMS8E#TRPBF LTDCJ 8-Lead Plastic MSOP –40°C to 125°C LT3580IMS8E#PBF
LT3580IMS8E#TRPBF
LTDCJ
8-Lead Plastic MSOP
–40°C to 125°C
Consult LTC Marketing for parts specifi ed with wider operating temperature ranges. *The temperature grade is identifi ed by a label on the shipping container. Consult LTC Marketing for information on non-standard lead based fi nish parts.For more information on lead free part marking, go to: www.linear/leadfree/ For more information on tape and reel specifi cations, go to: www.linear/tapeandreel/
SYNC Voltage ............................................–0.3V to 5.5V Operating Junction Temperature Range
L T3580E (Notes 2, 5) .........................–40°C to 125°C L T3580I (Notes 2, 5) ..........................–40°C to 125°C Storage Temperature Range ...................–65°C to 150°C
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 LT3580E is guaranteed to meet performance specifi cations from 0°C to 125°C junction temperature. Specifi cations over the –40°C to 125°C operating junction temperature range are assured by design, characterization and correlation with statistical process controls. The LT3580I is guaranteed over the full –40°C to 125°C operating junction temperature range.
ELECTRICAL CHARACTERISTICS The l denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at T A = 25°C. V IN = 5V, V SHDN = V IN unless otherwise noted. (Note 2)
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
Operating Voltage Range l 2.5 32
V Positive Feedback Voltage l 1.195 1.215 1.230V Negative Feedback Voltage l
0512mV Positive FB Pin Bias Current V FB = Positive Feedback Voltage, Current Into Pin l 8183.385μA Negative FB Pin Bias Current V FB = Negative Feedback Voltage, Current Out of Pin l
81
83.385.5
μA Error Amplifi er Transconductance
230μmhos Error Amplifi er Voltage Gain 70V/V
Quiescent Current
V SHDN = 2.5V, Not Switching 1 1.5mA Quiescent Current in Shutdown V SHDN = 0V 01μA Reference Line Regulation 2.5V ≤ V IN ≤ 32V 0.01
0.05%/V Switching Frequency, f OSC R T = 45.3k R T = 464k
l l 1.81802200 2.2220MHz kHz Switching Frequency in Foldback Compared to Normal f OSC 1/4
Ratio Switching Frequency Set Range SYNCing or Free Running
l 2002500kHz SYNC High Level for Synchronization l 1.3V SYNC Low Level for Synchronization l
0.4
V SYNC Clock Pulse Duty Cycle
V SYNC = 0V to 2V
35
65
%Recommended Minimum SYNC Ratio f SYNC /f OSC 3/4Minimum Off-Time 60nS Minimum On-Time 100
nS
Switch Current Limit Minimum Duty Cycle (Note 3)Maximum Duty Cycle (Notes 3, 4)l l 2.21.6 2.51.9 2.82.6A A Switch V CESAT
地沟油提炼I SW = 1.5A 300mV Switch Leakage Current V SW = 5V 0.01 1μA Soft-Start Charging Current V SS = 0.5V
l 468μA SHDN Minimum Input Voltage High
Active Mode, SHDN Rising Active Mode, SHDN Falling l l 1.271.24
1.321.29 1.381.33V V SHDN Input Voltage Low Shutdown Mode l
0.3V SHDN Pin Bias Current
V SHDN = 3V V SHDN = 1.3V V SHDN = 0V
9.7
4011.60
6013.40.1
μA μA μA
Note 3: Current limit guaranteed by design and/or correlation to static test.Note 4: Current limit measured at equivalent switching frequency of 2.5MHz.
Note 5: This IC includes overtemperature protection that is intended to protect the device during momentary overload conditions. Junction temperature will exceed 125°C when overtemperature protection is active. Continuous operation above the specifi ed maximum operating junction temperature may impair device reliability.
TYPICAL PERFORMANCE CHARACTERISTICS
Switch Current Limit at 1MHz
Switch Saturation Voltage
Switch Current Limit at Minimum
Duty Cycle
Switch Current Limit at Minimum Duty Cycle
Positive Feedback Voltage
Switching Waveforms for Figure 14 Circuit
Oscillator Frequency
Oscillator Frequency During Soft-Start
Internal UVLO
T A = 25°C unless otherwise specifi
ed DUTY CYCLE (%)
10
S W I T C H C U R R E N T L I M I T (A )
0.51.01.52.030
507090
3580 G01
2.520
4060
80
SWITCH CURRENT (A)
S A T U R A T I O N V O L T A G E (m V )
2002503002
3580 G02
15010000.51 1.5
50
400
350
SS VOL TAGE (mV)
00
S W I T C H C U R R E N T (A )
0.5
2.0200
4006008003580 G03
10001200
2.5TEMPERATURE (°C)
–50
0S W I T C H C U R R E N T L I M I T (A )
0.51.01.52.02.5
3.0050100
3580 G04
TEMPERATURE (°C)
–50
–25
1.19
F B V O L T A
G E (V )
1.21
1.24
05075
3580 G05
1.20
1.23
1.22
25100
125
V OUT 50mV/DIV AC COUPLED
V SW 10V/DIV
I L
果蔬包装机
0.5A/DIV
200ns/DIV
lzr种子
3580 G06
1.3
2.7
2.5
FB VOLTAGE (V)
0N O R M A L I Z E D O S C I L L A T O R F R E Q U E N C Y (F /F N O M )
1/4
1/2
1/31
0.2
0.40.60.83580 G08
1.0
1.2
TEMPERATURE (°C)一次性咖啡杯
–50
2.20
V I N V O L T A G E (V )2.222.26
2.282.302.40
2.34
503580 G09
2.242.362.382.32100
TYPICAL PERFORMANCE CHARACTERISTICS
SHDN Pin Current
SHDN Pin Current
Active/Lockout Threshold
T A = 25°C unless otherwise specifi ed
PIN FUNCTIONS
FB (Pin 1): Positive and Negative Feedback Pin. For a boost or inverting converter, tie a resistor from the FB pin to V OUT according to the following equations:
R FB =V OUT 1.215()83.3•10 6;Boost or SEPIC Converter
R FB =V OUT +5mV (
)83.3•10 6
;Inverting Converter
VC (Pin 2): Error Amplifi er Output Pin. Tie external com-pensation network to this pin.
V IN (Pin 3): Input Supply Pin. Must be locally bypassed.SW (Pin 4): Switch Pin. This is the collector of the internal NPN Power switch. Minimize the metal trace area con-nected to this pin to minimize EMI.
SHDN (Pin 5): Shutdown Pin. In conjunction with the UVLO (undervoltage lockout) circuit, this pin is used to enable/disable the chip and restart the soft-start sequence. Drive below 1.24V to disable the chip. Drive above 1.38V to activate chip and restart the soft-start sequence. Do not fl oat this pin.
RT (Pin 6): Timing Resistor Pin. Adjusts the switching frequency. Place a resistor from this pin to ground to set the frequency to a fi xed free running level. Do not fl oat this pin.
SS (Pin 7): Soft-Start Pin. Place a soft-start capacitor here. Upon start-up, the SS pin will be charged by a (nominally) 275k resistor to about 2.2V.
SYNC (Pin 8): To synchronize the switching frequency to an outside clock, simply drive this pin with a clock. The high voltage level of the clock needs to exceed 1.3V, and the low level should be less 0.4V. Drive this pin to less than 0.4V to revert to the internal free running clock. See the Applications
Information section for more information.Exposed Pad (Pin 9): Ground. Must be soldered directly to local ground plane.
SHDN VOLTAGE (V)
0S H D N P I N C U R R E N T (μA )
5
10152025300.5
1
1.5
2
3580 G10
SHDN VOLTAGE (V)
0S H D N P I N C U R R E N T (μA )
200250–50°C
20°C
100°C
300
15253580 G11
1501005
10
2030
500
TEMPERATURE (°C)
–50
1.20
S H D N V O L T A G E (V )
1.22
1.261.281.301.401.340
503580 G12
1.241.361.38
1.32100
BLOCK DIAGRAM
V OUT
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