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Final Electrical Specifications
LTC3401 1A, 3MHz Micropower Synchronous Boost Converter
September 2000
FEATURES
s s s s s
DESCRIPTIO
s s s s s s s s s s
Synchronous Rectification: Up to 97% Efficiency 1A Switch Current Rating Fixed Frequency Operation Up to 3MHz Wide Input Range: 0.5V to 5V (Operating) Very Low Quiescent Current: 38A (Burst ModeTM Operation) 2.6V to 5V Adjustable Output Voltage 0.85V (Typ) Start-Up Voltage No External Schottky Diode Required Synchronizable Switching Frequency Burst Mode Enable Control Antiringing Control Reduces Switching Noise PGOOD Output OPTI-LOOPTM Compensation Very Low Shutdown Current: < 1A Small 10-Pin MSOP Package
The LTC(R)3401 is a high efficiency, fixed frequency, stepup DC/DC converter that operates from an input voltage below 1V. The device includes a 0.16 N-channel MOSFET switch and a 0.18 P-channel synchronous rectifier. Switching frequencies up to 3MHz are programmed with an external timing resistor and the oscillator can be synchronized to an external clock. An external Schottky diode is optional but will slightly improve efficiency. Quiescent current is only 38A in Burst Mode operation, maximizing battery life in portable applications. Burst Mode operation is user controlled and can be enabled by driving the MODE/SYNC pin high. If the MODE/SYNC pin has either a clock or is driven low, then fixed frequency switching is enabled. Other features include a 1A shutdown, antiringing control, open-drain power good output, thermal shutdown and current limit. The LTC3401 is available in the 10-lead thermally enhanced MSOP package. Higher current applications should use the 2A rated LTC3402 synchronous boost converter.
, LTC and LT are registered trademarks of Linear Technology Corporation. Burst Mode and OPTI-LOOP are trademarks of Linear Technology Corporation.
APPLICATIO S
s s s s s s
Pagers Handheld Instruments Cordless Phones Wireless Handsets GPS Receivers Battery Backup
TYPICAL APPLICATIO
L1 4.7H 2 CELLS C1 4.7F
100
2-Cell to 3.3V at 500mA Step-Up Converter
EFFICIENCY (%)
Burst Mode 90 OPERATION 80 70 1MHz FIXED FREQUENCY
CC1 470pF CC2 20pF RC 40.2k Rt 30k
VIN SW PGOOD VOUT LTC3401 VC FB Rt SHDN MODE/SYNC GND
C1, C2: AVX TPS SERIES L1: SUMIDA CD43-4R7M fOSC = 1MHz R1 909k R2 549k
3401 TA01
60 50 40 30 20 10 0
C2 22F
3.3V 500mA
VIN = 2.4V WITH SCHOTTKY 0.1 1 10 IOUT (mA) 100 1000
3401 TA02
Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
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Efficiency
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1
LTC3401
ABSOLUTE
(Note 1)
AXI U
RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW Rt MODE VIN SW GND 1 2 3 4 5 10 9 8 7 6 SHDN VC FB VOUT PGOOD
VIN, VOUT Voltages ...................................... - 0.5V to 6V SW Voltage ................................................. - 0.5V to 6V VC, Rt, FB, MODE, SHDN Voltages ......................... - 0.5V to (VOUT + 0.3V) PGOOD Voltage .......................................... - 0.5V to 6V Operating Temperature Range (Note 2) .. - 40C to 85C Storage Temperature Range ................. - 65C to 125C Lead Temperature (Soldering, 10 sec).................. 300C
ORDER PART NUMBER LTC3401EMS MS10 PART MARKING LTPG
MS10 PACKAGE 10-LEAD PLASTIC MSOP TJMAX = 125C JA = 160C/ W 1 LAYER BOARD JA = 120C/ W 4 LAYER BOARD
Consult factory for Industrial and Military grade parts.
ELECTRICAL CHARACTERISTICS
The q denotes specifications that apply over the full operating temperature range, otherwise specifications are at TA = 25C. VIN = 1.2V, VOUT = 3.3V unless otherwise noted.
PARAMETER Minimum Start-Up Voltage Minimum Operating Voltage Output Voltage Adjust Range Feedback Voltage Feedback Input Current Quiescent Current--Burst Mode Operation Quiescent Current--SHDN Quiescent Current--Active NMOS Switch Leakage PMOS Switch Leakage NMOS Switch On Resistance PMOS Switch On Resistance NMOS Current Limit NMOS Burst Current Limit Maximum Duty Cycle Minimum Duty Cycle Frequency Accuracy MODE/SYNC Input High MODE/SYNC Input Low MODE/SYNC Input Current Error Amp Transconductance PGOOD Threshold VMODE/SYNC = 5.5V I = - 5A to 5A, VC = VFB Referenced to Feedback Voltage -6 0.01 85 -9 - 12 Rt = 15k Rt = 15k
q q q q
CONDITIONS ILOAD < 1mA (Note 4)
q q q
MIN
TYP 0.85
MAX 1.0 0.5 5
UNITS V V V V nA A A A A A A A %
2.6 1.22 1.25 1 38 0.1 440 0.1 0.1 0.16 0.18 1 80 1.6 1.4 1.6 0.66 85
1.28 50 65 1 800 5 10
VFB = 1.25V VC = 0V, MODE/SYNC = 3.3V (Note 3) SHDN = 0V, Not Including Switch Leakage VC = 0V, MODE/SYNC = 0V, Rt = 300k (Note 3)
0 2 2.4 0.4 1
mhos %
2
U
% MHz V V A
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WW
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LTC3401
ELECTRICAL CHARACTERISTICS
The q denotes specifications that apply over the full operating temperature range, otherwise specifications are at TA = 25C. VIN = 1.2V, VOUT = 3.3V unless otherwise noted.
PARAMETER PGOOD Low Voltage PGOOD Leakage SHDN Input High SHDN Input Low SHDN Input Current Thermal Shutdown Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: The LTC3401 is guaranteed to meet performance specifications from 0C to 70C. Specifications over the -40C to 85C operating temperature range are assured by design, characterization and correlation with statistical process controls. VSHDN = 5.5V 0.01 170 Note 3: Current is measured into the VOUT since the supply current is bootstrapped to the output pin and in the application will reflect to the input supply by (VOUT/VIN) * Efficiency. The outputs are not switching. Note 4: Once the output is started, the IC is not dependant upon the VIN supply. CONDITIONS IPGOOD = 1mA VOUT = 1V, IPGOOD = 20A VPGOOD = 5.5V VSHDN = VIN = VOUT 1 0.4 1 MIN TYP 0.1 0.1 0.01 MAX 0.2 0.4 1 UNITS V V A V V A C
TYPICAL PERFOR A CE CHARACTERISTICS
SW Pin and Inductor Current (IC) in Discontinuous Mode. Ringing Control Circuitry Eliminates High Frequency Ringing
IL 50mA/DIV 0A SW 1V/DIV
Switching Waveform on SW Pin
50ns/DIV
UW
3401 G01
Transient Response 5mA to 50mA
VOUT 100mV/DIV
SW 1V/DIV 50mA IOUT 0V 200ns/DIV
3401 G02
5mA COUT = 22F L = 3.3H fOSC = 1MHz 200s/DIV
3401 G03
3
LTC3401 TYPICAL PERFOR A CE CHARACTERISTICS
Transient Response 50mA to 500mA
VOUT AC 100mV/DIV
VOUT 200mV/DIV
550mA IOUT 50mA COUT = 22F L = 3.3H fOSC = 1MHz 200s/DIV
3401 G04
Converter Efficiency 1.2V to 3.3V
100 90 Burst Mode 80 OPERATION 70 EFFICIENCY (%)
EFFICIENCY (%) 100
300kHz
60 50 40 30 20 10 0 0.1
1MHz 3MHz
60 50 40 30 20 10
EFFICIENCY (%)
1 10 100 OUTPUT CURRENT (mA)
Start-Up Voltage vs IOUT
500 TA = 25C
14 12
OUTPUT CURRENT (mA)
400
EFFICIENCY LOSS (%)
300
8 6 4 2 0 0.2
CURRENT (A)
200
100
0 0.8 0.9 1 1.1 VIN (V) 1.2 1.3 1.4
3401 G09
4
UW
3401 G07
Burst Mode Operation
VOUT AC 100mV/DIV
Burst Mode Operation
SW 1V/DIV
SW 1V/DIV
5ms/DIV VIN = 1.2V VOUT = 3.3V COUT = 100F IOUT = 250A MODE/SYNC PIN = HIGH
3401 G05
VIN = 1.2V 200s/DIV VOUT = 3.3V COUT = 100F IOUT = 20mA MODE/SYNC PIN = HIGH
3401 G06
Converter Efficiency 2.4V to 3.3V
100
Burst Mode OPERATION 3MHz 300kHz 1MHz 90 80 70
Converter Efficiency 3.6V to 5V
Burst Mode OPERATION 90 80 70 60 50 40 30 20 10 1MHz FIXED FREQUENCY
1000
0 0.1
10 100 1 OUTPUT CURRENT (mA)
1000
3401 G08
0 0.1 1 100 10 LOAD CURRENT (mA) 1000
3401 G10
Efficiency Loss Without Schottky vs Frequency
1.80 1.75 1.70 1.65 1.60 1.55 1.50 1.45
0.6 1.0 1.4 1.8 2.2 FREQUENCY (MHz) 2.6 3.0
Current Limit
10
1.40 -55
-15
25 65 TEMPERATURE (C)
105 125
3401 G12
3401 G11
LTC3401 TYPICAL PERFOR A CE CHARACTERISTICS
EA FB Voltage
1.28 1.27 2.05
FREQUENCY (MHz)
VOLTAGE (V)
1.26 1.25 1.24 1.23 1.22 -55
RESISTANCE ()
-15
65 TEMPERATURE (C)
25
PMOS RDS(ON)
0.30 VOUT = 3.3V 1.1
0.25
RESISTANCE ()
VOLTAGE (V)
0.20
0.9
VOLTAGE (V)
0.15
0.10
0.05 -55
-15
25 65 TEMPERATURE (C)
PGOOD Threshold
-7.0 -7.5
PERCENT FROM VFB (%)
-8.0 -8.5 40
CURRENT (A)
-9.0 -9.5
VOLTAGE (V)
-10.0
-10.5 -11.0 -11.5 -12.0 -55 -15 65 TEMPERATURE (C) 25 105 125
3401 G19
UW
Oscillator Frequency Accuracy
2.10 0.30
NMOS RDS(ON)
VOUT = 3.3V
0.25
0.20
2.00
0.15
1.95 0.10
105 125
3401 G13
1.90 -55
-15
65 TEMPERATURE (C)
25
105 125
3401 G14
0.05 -55
-15
25 65 TEMPERATURE (C)
105 125
3401 G22
Start-Up Voltage
1.10 1.05 1.0 1.00 0.95 0.90 0.85 0.80 0.75 0.7 0.70 0.65 105 125
3401 G16
Shutdown Threshold
0.8
0.6 -55
-15
25 65 TEMPERATURE (C)
105 125
3401 G17
0.60 -55
-15
25 65 TEMPERATURE (C)
105 125
3401 G18
Burst Mode Operation Current
44 42 2.50 2.45 2.40 2.35 2.30 2.25 2.20 2.15 2.10 32 30 -55 2.05 -15 65 TEMPERATURE (C) 25 105 125
3401 G20
VOUT Turn-Off Voltage
38 36 34
2.00 -55
-15
25 65 TEMPERATURE (C)
105 125
3401 G21
5
LTC3401
PI FU CTIO S
Rt (Pin 1): Timing Resistor to Program the Oscillator Frequency.
fOSC =
3 * 1010 Hz Rt
MODE/SYNC (Pin 2): Burst Mode Select and Oscillator Synchronization. MODE/SYNC = High. Enable Burst Mode operation. The inductor peak inductor current will be 1/3 the current limit value and return to zero current on each cycle. During Burst Mode operation the operation is variable frequency, providing a significant efficiency improvement at light loads. It is recommended the Burst Mode operation only be entered once the part has started up. MODE/SYNC = Low. Disable Burst Mode operation and maintain low noise, constant frequency operation. MODE/SYNC = External CLK. Synchronization of the internal oscillator and Burst Mode operation disable. A clock pulse width of 100ns to 2s is required to synchronize. VIN (Pin 3): Input Supply Pin.
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SW (Pin 4): Switch Pin. Connect inductor and optional Schottky diode here. Minimize trace length to keep EMI and high ringing down. For discontinuous inductor current, a controlled impedance is placed from SW to VIN from the IC to eliminate high frequency ringing due to the resonant tank of the inductor and SW node capacitance, therefore reducing EMI radiation. GND (Pin 5): Signal and Power Ground for the IC. PGOOD (Pin 6): Power Good Comparator Output. This open-drain output is low when VFB < - 9% from its regulation voltage. VOUT (Pin 7): Output of the Synchronous Rectifier and Bootstrapped Power Source for the IC. FB (Pin 8): Feedback Pin. Connect resistor divider tap here. The output voltage can be adjusted from 2.6V to 5V. The feedback reference voltage is typically 1.25V. VC (Pin 9): Error Amp Output. A frequency compensation network is connected to this pin to compensate the loop. See the section "Compensating the Feedback Loop" for guidelines. SHDN (Pin 10): Shutdown. Grounding this pin shuts down the IC. Tie to >1V to enable. A 1M to VIN is sufficient. An additional resistor to VOUT (5M) will allow the IC to operate lower once started.
LTC3401
BLOCK DIAGRA
3
VIN ANTIRING
SHDN 10
SHUTDOWN
GND
5
PWM LOGIC SLEEP
+
-
9 Burst Mode CONTROL
Rt
1
OSC
SYNC SLOPE COMP
PGOOD 6 N
1.25V - 9%
3401 BD
-
CURRENT COMP
ERROR AMP 8
+
-
-
+
+
-
+
W
+
1V TO VOUT + 0.3 OPTIONAL SW P 7 VOUT 4 VOUT 2.6V TO 5V ANTICROSS COND N ISENSE AMP 10mV
+ -
IZERO AMP
+
CURRENT LIMIT
1.6A TYP
1.25V R1 FB
VC
R2
2 MODE/SYNC
7
LTC3401
APPLICATIO S I FOR ATIO
DETAILED DESCRIPTION
The LTC3401 provides high efficiency, low noise power for applications such as portable instrumentation. The current mode architecture with adaptive slope compensation provides ease of loop compensation with excellent transient load response. The low RDS(ON), low gate charge synchronous switches provide the pulse width modulation control at high efficiency. The Schottky diode across the synchronous PMOS switch is not required, but provides a lower drop during the breakbefore-make time (typically 20ns) of the NMOS to PMOS transition. The addition of the Schottky diode will improve peak efficiency by typically 1% to 2%. While the IC's quiescent current is a low 38A, high efficiency is achieved at light loads when Burst Mode operation is entered. Low Voltage Start-Up The LTC3401 is designed to start up at input voltages of typically 0.85V. The device can start up under some load, (see graph Start-Up vs Input Voltage). Once the output voltage exceeds a threshold of 2.3V, then the IC powers itself from VOUT instead of VIN. At this point, the internal circuitry has no dependency on the VIN input voltage, eliminating the requirement for a large input capacitor. The input voltage can drop below 0.5V without affecting the operation, but the limiting factor for the application becomes the availability of the power source to supply sufficient energy to the output at the low voltages. Low Noise Fixed Frequency Operation Oscillator. The frequency of operation is set through a resistor from the Rt pin to ground where f = 3 * 1010/Rt. An internally trimmed timing capacitor resides inside the IC. The oscillator can be synchronized with an external clock inserted on the MODE/SYNC pin. When synchronizing the oscillator, the free running frequency must be set to approximately 30% lower than the desired synchronized frequency. Keeping the sync pulse width below 2s will ensure that Burst Mode operation is disabled. Current Sensing. Lossless current sensing converts the peak current signal to a voltage to sum in with the internal slope compensation. This summed signal is compared to
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the error amplifier output to provide a peak current control command for the PWM. The slope compensation in the IC is adaptive to the input and output voltage. Therefore, the converter provides the proper amount of slope compensation to ensure stability and not an excess causing a loss of phase margin in the converter. Error Amp. The error amplifier is a transconductance amplifier with gm = 0.1ms. A simple compensation network is placed from the VC pin to ground. Current Limit. The current limit amplifier will shut the NMOS switch off once the current exceeds its threshold. The current amplifier delay to output is typically 50ns. Zero Current Amp. The zero current amplifier monitors the inductor current to the output and shuts off the synchronous rectifier once the current is below 50mA, preventing negative inductor current. Antiringing Control. The anitringing control will place an impedance across the inductor to damp the ringing on the SW pin during discontinuous mode operation. The LCSW ringing (L = inductor, CSW = capacitance on the switch pin) is low energy, but can cause EMI radiation. Burst Mode Operation Burst Mode operation is when the IC delivers energy to the output until it is regulated and then goes into a sleep mode where the outputs are off and the IC is consuming only 38A. In this mode, the output ripple has a variable frequency component with load current and the steady state ripple will be typically below 3%. During the period where the device is delivering energy to the output, the peak current will be equal to 1/3 the current limit value and the inductor current will terminate at zero current for each cycle. In this mode the maximum output current is given by:
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I OUT(MAXBURST)
VIN Amps 6 * VOUT
Burst Mode operation is user controlled by driving the MODE/SYNC pin high to enable and low to disable. It is recommended that Burst Mode operation be entered after the part has started up.
LTC3401
APPLICATIO S I FOR ATIO
COMPONENT SELECTION Inductor Selection
The high frequency operation of the LTC3401 allows the use of small surface mount inductors. The minimum inductance value is proportional to the operating frequency and is limited by the following constraints: VIN(MIN) * VOUT(MAX) - VIN(MIN) 3 H L > H and L > f * Ripple * VOUT(MAX) f where f = Operating Frequency (Hz) Ripple = Allowable Inductor Current Ripple (A) VIN(MIN) = Minimum Input Voltage (V) VOUT(MAX) = Maximum Output Voltage (V) The inductor current ripple is typically set to 20% to 40% of the maximum inductor current.
(
SHDN Rt MODE VC VIN FB SW VOUT GND PGOOD
VOUT
3401 F01
Figure 1. Recommended Component Placement. Traces Carrying High Current Are Direct. Trace Area FB and VC Pins Are Kept Low. Lead Length to Battery Should be Kept Short
Table 1. Inductor Vendor Information
SUPPLIER Coilcraft Coiltronics Murata Sumida PHONE (847) 639-6400 (516) 241-7876 (814) 237-1431 (800) 831-9172 USA: (847) 956-0666 Japan: 81-3-3607-5111 FAX (847) 639-1469 (516) 241-9339 (814) 238-0490 (847) 956-0702 81-3-3607-5144 WEBSITE www.coilcraft.com www.coiltronics.com www.murata.com www.japanlink.com sumida
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)
For high efficiency, choose an inductor with a high frequency core material, such as ferrite, to reduce core losses. The inductor should have low ESR (equivalent series resistance) to reduce the I2R losses and must be able to handle the peak inductor current at full load without saturating. Molded chokes or chip inductors usually do not have enough core to support the peak inductor currents in the 1A to 2A region. To minimize radiated noise, use a toroid, pot core or shielded bobbin inductor. See Table 1 for a list of component suppliers. Output Capacitor Selection The output voltage ripple has three components. The bulk value of the capacitor is set to reduce the ripple due to charge into the capacitor each cycle. The max ripple due to charge is given by:
VRBULK =
where
IP * VIN V COUT * VOUT * f
IP = Peak Inductor Current The ESR is usually the most dominant factor for ripple in most power converters. The ripple due to capacitor ESR is simply given by: VRCESR = IP * RESR V where RESR = Capacitor Series Resistance Low ESR capacitors should be used to minimize output voltage ripple. For surface mount applications, AVX TPS series tantalum capacitors and Sanyo POSCAP or TaiyoYuden ceramic capacitors are recommended. For throughhole applications Sanyo OS-CON capacitors offer low ESR in a small package size.
9
LTC3401
APPLICATIO S I FOR ATIO
In some layouts it may be required to place a 1F low ESR capacitor as close to the VOUT and GND pins as possible. Input Capacitor Selection The input filter capacitor reduces peak currents drawn from the input source and reduces input switching noise. Since the IC can operate at voltages below 0.5V once the output is regulated, then demand on the input capacitor is much less and in most applications a 3.3F is recommended. Output Diode The Schottky diode across the synchronous PMOS switch is not required, but provides a lower drop during the breakbefore-make time (typically 20ns) of the NMOS to PMOS transition. The addition of the Schottky diode will improve peak efficiency (see graph "Efficiency Loss Without Schottky vs Frequency"). Use of a Schottky diode such as a MBR0520L, 1N5817 or equivalent. Since slow recovery times will compromise efficiency, do not use ordinary rectifier diodes. Operating Frequency Selection There are several considerations in selecting the operating frequency of the converter. The first is determining the sensitive frequency bands that cannot tolerate any spectral noise. For example, in products incorporating RF communications, the 455kHz IF frequency is sensitive to
100 90 80 70 EFFICIENCY (%) 60 50 40 30 20 10 0 0.1 300kHz Burst Mode OPERATION
Figure 2. Converter Efficiency 2.4V to 3.3V
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any noise, therefore switching above 600kHz is desired. Some communications have sensitivity to 1.1MHz. In this case, a 2MHz or 3MHz converter frequency may be employed. The second consideration is the physical size of the converter. As the operating frequency goes up, the inductor and filter caps go down in value and size. The trade off is in efficiency since the switching losses due to gate charge are going up proportional with frequency. For example in Figure 2, for a 2.4V to 3.3V converter, the efficiency at 100mA is 5% less at 2MHz compared to 300kHz. Another operating frequency consideration is whether the application can allow "pulse skipping." In this mode, the minimum on time of the converter cannot support the duty cycle, so the converter ripple will go up and there will be a low frequency component of the output ripple. In many applications where physical size is the main criterion then running the converter in this mode is acceptable. In applications where it is preferred not to enter this mode, then the maximum operating frequency is given by:
fMAX _ NOSKIP = VOUT - VIN Hz VOUT * tON(MIN)
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where tON(MIN) = minimum on time = 120ns
3MHz 1MHz
1 10 100 OUTPUT CURRENT (mA)
1000
3401 G08
LTC3401
APPLICATIO S I FOR ATIO
Closing the Feedback Loop
The LTC3401 uses current mode control with internal adaptive slope compensation. Current mode control eliminates the 2nd order filter due to the inductor and output capacitor exhibited in voltage mode controllers, and simplifies it to a single-pole filter response. The product of the modulator control to output DC gain plus the error amp open-loop gain equals the DC gain of the system. GDC = GCONTROLOUTPUT * GEA
2 * VIN GCONTROL = , GEA 2000 IOUT
The output filter pole is given by:
fFILTERPOLE =
IOUT Hz * VOUT * COUT
where COUT is the output filter capacitor. The output filter zero is given by:
fFILTERZERO =
1 2 * * RESR * COUT
Hz
where RESR is the capacitor equivalent series resistance.
VOUT
ERROR AMP
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A troublesome feature of the boost regulator topology is the right half plane zero (RHP) and is given by:
fRHPZ = VIN RO
2 2LVO 2
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Hz
At heavy loads this gain increase with phase lag can occur at a relatively low frequency. The loop gain is typically rolled off before the RHP zero frequency. The typical error amp compensation is shown in Figure 3. The equations for the loop dynamics are as follows:
fPOLE1 1
Hz 2 * * 20 * 106 * CC1 which is extremelyclose to DC 1 f ZERO1 = Hz 2 * * RZ * CC1 1 fPOLE2 Hz 2 * * RZ * CC2
+ -
1.25V FB 8 VC 9 CC1 RZ
3401 F03
R1
R2
CC2
Figure 3
11
LTC3401
TYPICAL APPLICATIO S
Single Cell to 3V at 50mA, 3MHz Step-Up Converter
L1 2.2H 1 CELL C1 3.3F D1 C1, C2: AVX TPS SERIES D1: CENTRAL SEMICONDUCTOR CMDSH2-3 L1: TAIYO YUDEN LB2016 VOUT 3V C2 50mA 4.7F
CC2 20pF
EFFICIENCY (%)
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CC1 470pF RC 40k Rt 10k
VIN SW PGOOD VOUT LTC3401 VC FB Rt SHDN MODE/SYNC GND
R1 870k R2 620k
3401 TA03a
Efficiency
90 80 70 60 50 40 30 20 10 0 0.1 1 10 100 OUTPUT CURRENT (mA) 1000
3401 TA03b
Burst Mode OPERATION FIXED FREQUENCY
LTC3401
TYPICAL APPLICATIO S
Single Cell to 3V at 100mA, 600kHz Step-Up Converter
1 CELL
CC2 100pF
EFFICIENCY (%)
U
L1 10H C1 3.3F
D1
C1, C2: AVX TPS SERIES D1: MOTOROLA MBR0520L L1: COILCRAFT DO3316P-103
CC1 3000pF RC 40k Rt 50k
VIN SW PGOOD VOUT LTC3401 VC FB SHDN Rt MODE/SYNC GND
R1 870k R2 620k
VOUT 3V C2 200mA 22F
3401 TA04a
Efficiency
100 90 80 70 60 50 40 30 20 10 0 0.1 1 100 10 LOAD CURRENT (mA) 1000
3401 TA04b
Burst Mode OPERATION 1MHz FIXED FREQUENCY
13
LTC3401
TYPICAL APPLICATIO S
Li-Ion to 5V at 300mA, 1MHz Step-Up Converter
2.5V T0 4.2V
CC2 20pF
EFFICIENCY (%)
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L1 10H C1 4.7F
D1
C1, C2: AVX TPS SERIES D1: MOTOROLA MBR0520L L1: COILCRAFT DO3316P-103
CC1 630pF RC 40k Rt 30k
VIN SW PGOOD VOUT LTC3401 VC FB Rt SHDN MODE/SYNC GND
R1 1.85M R2 620k
C2 22F
VOUT 5V 300mA
3401 TA05a
Efficiency
100 90 80 70 60 50 40 30 20 10 0 0.1 1 100 10 LOAD CURRENT (mA) 1000
3401 G10
Burst Mode OPERATION
1MHz FIXED FREQUENCY
LTC3401
PACKAGE DESCRIPTION U
Dimensions in inches (millimeters) unless otherwise noted.
MS10 Package 10-Lead Plastic MSOP
(LTC DWG # 05-08-1661)
0.118 0.004* (3.00 0.102)
10 9 8 7 6
0.193 0.006 (4.90 0.15)
0.118 0.004** (3.00 0.102)
12345
0.040 0.006 (1.02 0.15) 0.007 (0.18) 0.021 0.006 (0.53 0.015) 0 - 6 TYP SEATING PLANE 0.009 (0.228) REF
0.034 0.004 (0.86 0.102)
0.0197 (0.50) BSC
0.006 0.004 (0.15 0.102)
MSOP (MS10) 1098
* DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE ** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
15
LTC3401
TYPICAL APPLICATIO
+
2 CELLS
CC1 470pF CC2 20pF RC 40.2k Rt 15k
C1, C2: AVX TPS SERIES D1: MOTOROLA MBR0520L D2 TO D7: ZETEX FMND7000 DUAL DIODE
RELATED PARTS
PART NUMBER LT1306 LT1308A/LT1308B LT1317/LT1317B LT1610 LT1613 LT1615 LT1949 LT3402 DESCRIPTION Sync, Fixed Frequency, Step-Up DC/DC Converter High Current, Micropower, Single Cell 600kHz DC/DC Converter Micropower 600kHz PWM DC/DC Converter 1.7MHz, Single Cell Micropower DC/DC Converter 1.4MHz, Single Cell DC/DC Converter in SOT-23 Micropower Step-Up DC/DC Converter in SOT-23 600kHz, 1A Switch PWM DC/DC Converter Single Cell, High Current (2A) Micropower, Synchronous 3MHz Step-Up DC/DC Converter COMMENTS Internal 2A Switches, VIN As Low As 1.8V 5V at 1A from Single Li-Ion Cell VIN As Low As 1.5V, IQ = 100A 3V at 30mA from 1V, 5V at 200mA from 3.3V VIN As Low As 1.1V, 3V at 30mA from Single Cell IQ = 20A, 1A Shutdown Current, VIN As Low As 1V 1.1A, 0.5/30V Internal Switch, VIN As Low As 1.8V VIN = 0.7V to 5V, Up to 95% Efficiency Synchronizable Oscillator from 100kHz to 3MHz
16
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408)432-1900 q FAX: (408) 434-0507 q www.linear-tech.com
U
Triple Output Converter
D2 D3 D4 D5 8V 2mA 0.1F L1 4.7H C1 10F 0.1F 0.1F 4.7F D1 VIN SW PGOOD VOUT LTC3401 VC FB SHDN Rt MODE/SYNC GND 0.1F R1 866k R2 619k VOUT 3V C2 500mA 10F D6 4.7F D7 -2.5V 1mA
3401 TA06
3401i LT/TP 0900 4K * PRINTED IN USA
(c) LINEAR TECHNOLOGY CORPORATION 2000

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