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Final Electrical Specifications
LT1930 1.2MHz Boost DC/DC Converter in SOT-23
June 2000
FEATURES
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DESCRIPTIO
1.2MHz Switching Frequency High Output Voltage: Up to 34V Wide Input Range: 2.6V to 16V Low VCESAT Switch: 400mV at 1A Uses Small Surface Mount Components 5V at 480mA from 3.3V Input 12V at 300mA from 5V Input Low Shutdown Current: < 1A 5-Lead SOT-23 Package Pin-for-Pin Compatible with the LT1613
The LT(R)1930 is the industry's highest power SOT-23 switching regulator. Its internal 1A, 36V switch allows high current outputs to be generated in a small footprint. Intended for space-conscious applications, the LT1930 switches at 1.2MHz, allowing the use of tiny, low cost capacitors and inductors 2mm or less in height. Multiple output power supplies can now use a separate regulator for each output voltage, replacing cumbersome quasiregulated approaches using a single regulator and custom transformers. A constant frequency, internally compensated, current mode PWM architecture results in low, predictable output noise that is easy to filter. Low ESR ceramic capacitors can be used on the output, further reducing noise to the millivolt level. The high voltage switch on the LT1930 is rated at 36V, making the device ideal for boost converters up to 34V as well as for single-ended primary inductance converter (SEPIC) and flyback designs. The device can generate 5V at up to 480mA from a 3.3V supply or 5V at 300mA from four alkaline cells in a SEPIC design. The LT1930 is available in the 5-lead SOT-23 package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
APPLICATIO S
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Digital Cameras Cordless Phones Battery Backup LCD Bias Medical Diagnostic Equipment Local 5V or 12V Supply External Modems PC Cards xDSL Power Supply
TYPICAL APPLICATIO
VIN 5V C1 2.2F SHDN 4 L1 10H 5 VIN LT1930 SHDN GND 2 C1: TAIYO-YUDEN X5R LMK212BJ225MG C2: TAIYO-YUDEN X5R EMK316BJ475ML D1: ON SEMICONDUCTOR MBR0520 L1: SUMIDA CR43-100 *OPTIONAL FB 3 1 SW D1
90
VOUT 12V 300mA
85 VIN = 3.3V 80
EFFICIENCY (%)
R1 113k
C3* 10pF C2 4.7F
75 70 65 60
R2 13.3k
1930 F01
55 50 0 200 100 300 LOAD CURRENT (mA) 400
1930 TA01
Figure 1. 5V to 12V, 300mA Step-Up DC/DC Converter
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 represenThis Material Copyrighted By Its Respective tation that the interconnection of its circuits as described herein will not infringe on existing patent rights. Manufacturer
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Efficiency
VIN = 5V
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LT1930
ABSOLUTE
(Note 1)
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RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW SW 1 GND 2 FB 3 4 SHDN 5 VIN
VIN Voltage .............................................................. 16V SW Voltage ................................................- 0.4V to 36V FB Voltage .............................................................. 2.5V Current Into FB Pin .............................................. 1mA SHDN Voltage ......................................................... 10V Maximum Junction Temperature ......................... 125C Operating Temperature Range (Note 2) .. - 40C to 85C Storage Temperature Range ................. - 65C to 150C Lead Temperature (Soldering, 10 sec).................. 300C
ORDER PART NUMBER LT1930ES5
S5 PACKAGE 5-LEAD PLASTIC SOT-23
S5 PART MARKING LTKS
TJMAX = 125C, JA = 256C/ W
Consult factory for Industrial and Military grade parts.
ELECTRICAL CHARACTERISTICS
The q denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25C. VIN = 3V, VSHDN = VIN unless otherwise noted. (Note 2)
PARAMETER Minimum Operating Voltage Maximum Operating Voltage Feedback Voltage
q
CONDITIONS
MIN
TYP 2.45
MAX 2.6 16 1.270 1.280 360 6 1 0.05 1.4 1.6 2 500 1 0.5
UNITS V V V V nA mA A %/V MHz MHz % A mV A V V A A
1.240 1.230
1.255 120 4.2 0.01 0.01
FB Pin Bias Current Quiescent Current Quiescent Current in Shutdown Reference Line Regulation Switching Frequency VSHDN = 1.5V, Not Switching VSHDN = 0V, VIN = 3V 2.6V VIN 16V
q
q
1 0.85 82 1
1.2 90 1.2 350 0.01
Maximum Duty Cycle Switch Current Limit Switch VCESAT Switch Leakage Current SHDN Input Voltage High SHDN Input Voltage Low SHDN Pin Bias Current VSHDN = 3V VSHDN = 0V (Note 3) ISW = 900mA VSW = 5V
q
2.4 16 0.01 32 0.1
Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: The LT1930ES5 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. Note 3: Current limit guaranteed by design and/or correlation to static test.
This Material Copyrighted By Its Respective Manufacturer
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LT1930 TYPICAL PERFOR A CE CHARACTERISTICS
Quiescent Current
4.6 4.5 QUIESCENT CURRENT (mA) 4.4 4.3 4.2 4.1 4.0 3.9 3.8 3.7 3.6 -50 -25 50 0 25 TEMPERATURE (C) 75 100
1930 G01
VFB = 1.3V NOT SWITCHING
SHUTDOWN PIN CURRENT (A)
FEEDBACK VOLTAGE (V)
VIN = 3.3V
Current Limit
1.6 1.4 0.45 0.40
CURRENT LI MIT (A)
1.2 VCESAT (V) 1.0 0.8 0.6 0.4 0.2 0 10 20 30 40 50 60 70 DUTY CYCLE (%) 80 90
0.30 0.25 0.20 0.15 0.10
FREQUENCY (MHz)
PI FU CTIO S
SW (Pin 1): Switch Pin. Connect inductor/diode here. Minimize trace area at this pin to reduce EMI. GND (Pin 2): Ground. Tie directly to local ground plane. FB (Pin 3): Feedback Pin. Reference voltage is 1.255V. Connect resistive divider tap here. Minimize trace area at FB. Set VOUT according to VOUT = 1.255V(1 + R1/R2). SHDN (Pin 4): Shutdown Pin. Tie to 2.4V or more to enable device. Ground to shut down. VIN (Pin 5): Input Supply Pin. Must be locally bypassed.
This Material Copyrighted By Its Respective Manufacturer
UW
VIN = 5V
1930 G04
Feedback Pin Voltage
1.28 1.27 1.26 1.25 1.24 1.23 1.22 -50
Shutdown Pin Current
40 35 30 TA = 25C 25 20 15 10 5 TA = 100C
-25
0 25 50 TEMPERATURE (C)
75
100
1930 G02
0
0
1
2 4 5 3 SHUTDOWN PIN VOLTAGE (V)
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1930 G03
Switch Saturation Voltage
1.35 1.30
0.35
Oscillator Frequency
1.25 1.20 1.15 1.10
0.05 0 0 0.2 0.4 0.6 0.8 SWITCH CURRENT (A) 1.0 1.2
1.05 -50 -30 -10 10 30 50 70 TEMPERATURE (C)
90
110
1930 G05
1930 G06
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LT1930
BLOCK DIAGRA
VIN 5
A1
-
VOUT R1 (EXTERNAL) FB R2 (EXTERNAL)
RC CC
-
RAMP GENERATOR
SHUTDOWN
4 SHDN
FB 3 1.2MHz OSCILLATOR
Figure 2. Block Diagram
OPERATIO
The LT1930 uses a constant frequency, current mode control scheme to provide excellent line and load regulation. Operation can be best understood by referring to the Block Diagram in Figure 2. At the start of each oscillator cycle, the SR latch is set, turning on the power switch Q1. A voltage proportional to the switch current is added to a stabilizing ramp and the resulting sum is fed into the positive terminal of the PWM comparator, A2. When this voltage exceeds the level at the negative input of A2, the SR latch is reset, turning off the power switch. The level at the negative input of A2 is set by error amplifier A1, and is simply an amplified version of the difference between
the feedback voltage and the reference voltage of 1.255V. In this manner, the error amplifier sets the correct peak current level to keep the output in regulation. If the error amplifier's output increases, more current is delivered to the output; if it decreases, less current is delivered. One function present in the LT1930 but not shown in Figure 2 is current limit. The switch current is constantly monitored and not allowed to exceed the nominal value of 1A. If the switch current reaches 1A, the SR latch is reset regardless of the state of comparator A2. This current limit protects the power switch as well as the external components connected to the LT1930.
APPLICATIONS INFORMATION
Inductor Selection Several inductors that work well with the LT1930 are listed in Table 1, although there are many other manufacturers and devices that can be used. Consult each manufacturer for more detailed information and for their entire selection of related parts, as many different sizes and shapes are available. Ferrite core inductors should be used to obtain the best efficiency, as core losses at 1.2MHz are much lower for ferrite cores than for the cheaper powdered-iron cores. Choose an inductor that can handle at least 1A without saturating, and ensure that the inductor has a low DCR (copper wire resistance) to minimize I2R power losses. A 4.7H or 10H inductor will be the best choice for most LT1930 designs. Note that in some applications, the current handling requirements of the inductor can be lower, such as in the SEPIC topology where each inductor only carries one-half of the total switch current.
This Material Copyrighted By Its Respective Manufacturer
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1.255V REFERENCE
+
1 SW COMPARATOR DRIVER A2 R S Q Q1
+
0.01
2 GND
1939 BD
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LT1930
APPLICATIONS INFORMATION
Table 1. Recommended Inductors
L (H) 4.1 10 4.7 10 4.7 10 4.7 10 MAX DCR m 57 124 109 182 60 75 84 137 HEIGHT (mm) 2.0 2.0 3.5 3.5 2.9 2.9 2.0 2.0
PART CDRH5D18-4R1 CDRH5D18-100 CR43-4R7 CR43-100 DS1608-472 DS1608-103 D52LC-4R7M D52LC-100M
VENDOR Sumida (847) 956-0666 www.sumida.com Coilcraft (847) 639-6400 www.coilcraft.com Toko (408) 432-8282 www.tokoam.com
Capacitor Selection Low ESR (equivalent series resistance) capacitors should be used at the output to minimize the output ripple voltage. Multilayer ceramic capacitors are an excellent choice, as they have extremely low ESR and are available in very small packages. X5R dielectrics are preferred, followed by X7R, as these materials retain the capacitance over wide voltage and temperature ranges. A 4.7F to 10F output capacitor is sufficient for most applications, but systems with very low output current may need only a 1F or 2.2F output capacitor. Solid tantalum or OS-CON capacitors can be used, but they will occupy more board area than a ceramic and will have a higher ESR. Always use a capacitor with a sufficient voltage rating. Ceramic capacitors also make a good choice for the input decoupling capacitor, and should be placed as close as possible to the LT1930. A 1F to 4.7F input capacitor is sufficient for most applications. Table 2 shows a list of several ceramic capacitor manufacturers. Consult the manufacturers for detailed information on their entire selection of ceramic parts.
Table 2. Ceramic Capacitor Manufacturers
Taiyo-Yuden AVX Murata (408) 573-4150 (803) 448-9411 (714) 852-2001 www.t-yuden.com www.avxcorp.com www.murata.com
The decision to use either low ESR (ceramic) capacitors or the higher ESR (tantalum or OS-CON) capacitors can
This Material Copyrighted By Its Respective Manufacturer
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affect the stability of the overall system. The ESR of any capacitor, along with the capacitance itself, contributes a zero to the system. For the tantalum and OS-CON capacitors, this zero is located at a lower frequency due to the higher value of the ESR, while the zero of a ceramic capacitor is at a much higher frequency and can generally be ignored. A phase lead zero can be intentionally introduced by placing a capacitor (C3) in parallel with the resistor (R1) between VOUT and VFB as shown in Figure 1. The frequency of the zero is determined by the following equation. Z = 1 2 * R1 * C3
By choosing the appropriate values for the resistor and capacitor, the zero frequency can be designed to slightly improve the phase margin of the overall converter. The typical target value for the zero frequency is between 50kHz to 150kHz. Figure 3 shows the transient response of the step-up converter from Figure 1 without the phase lead capacitor C3. The phase margin is reduced as evidenced by more ringing in both the output voltage and inductor current. A 10pF capacitor for C3 results in better phase margin, which is revealed in Figure 4 as a more damped response and less overshoot. Figure 5 shows the transient response when a 33F tantalum capacitor with no phase lead capacitor is used on the output. The higher output voltage ripple is revealed in the upper waveform as a set of double lines. The transient response is not greatly improved which implies that the ESR zero frequency is too high to increase the phase margin.
VOUT 0.2V/DIV AC COUPLED ILI 0.5A/DIV AC COUPLED LOAD 250mA CURRENT 150mA 50s/DIV
1930 F03
Figure 3. Transient Response of Step-Up Converter Without Phase Lead Capacitor
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LT1930
APPLICATIONS INFORMATION
VOUT 0.2V/DIV AC COUPLED ILI 0.5A/DIV AC COUPLED LOAD 250mA CURRENT 150mA 50s/DIV
1930 F04
Figure 4. Transient Response of Step-Up Converter with 10pF Phase Lead Capacitor
VOUT 0.2V/DIV AC COUPLED
D1 VOUT L1 C1
ILI 0.5A/DIV AC COUPLED LOAD 250mA CURRENT 150mA 200s/DIV
1930 F04
Figure 5. Transient Response of Step-Up Converter with 33F Tantalum Output Capacitor and No Phase Lead Capacitor
Diode Selection A Schottky diode is recommended for use with the LT1930. The ON Semiconductor MBR0520 is a very good choice. Where the input to output voltage differential exceeds 20V, use the MBR0530 (a 30V diode). These diodes are rated to handle an average forward current of 0.5A. In applications where the average forward current of the diode exceeds 0.5A, a Microsemi UPS5817 rated at 1A is recommended. Setting Output Voltage To set the output voltage, select the values of R1 and R2 (see Figure 1) according to the following equation:
V R1 = R2 OUT - 1 1.255V
A good value for R2 is 13.3k which sets the current in the resistor divider chain to 1.255V/13.3k = 94.4A.
This Material Copyrighted By Its Respective Manufacturer
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Layout Hints The high speed operation of the LT1930 demands careful attention to board layout. You will not get advertised performance with careless layout. Figure 6 shows the recommended component placement. Make the ground pin copper area large. This helps to lower the die temperature.
+
VIN
+
C2 R2 SHUTDOWN
GND
R1
C3
1930 F06
Figure 6. Suggested Layout
Driving SHDN Above 10V The maximum voltage allowed on the SHDN pin is 10V. If you wish to use a higher voltage, you must place a resistor in series with SHDN. A good value is 121k. Figure 7 shows a circuit where VIN = 16V and SHDN is obtained from VIN. The voltage on the SHDN pin is kept below 10V.
VIN 16V C1 121k 4 L1 5 VIN LT1930 SHDN GND 2
1930 F07
D1 VOUT 1 SW 3 R2 R1 C2
FB
Figure 7. Keeping SHDN Below 10V
LT1930
TYPICAL APPLICATIO S
Efficiency 4-Cell to 5V SEPIC Converter
4V TO 6.5V 5 C1 2.2F 4-CELL BATTERY SHDN 4 VIN LT1930 SHDN GND 2
40 80 75 VIN = 4V VIN = 6.5V
EFFICIENCY (%)
L1 10H 1 SW
C1: TAIYO-YUDEN X5R LMK212BJ225MG C2: TAIYO-YUDEN X5R JMK316BJ106ML D1: ON SEMICONDUCTOR MBR0520 C3: TAIYO-YUDEN X5R LMK212BJ105MG L1: MURATA LQH3C100K24
4V TO 6.5V 5 C1 2.2F 4-CELL BATTERY SHDN 4 VIN
PACKAGE DESCRIPTIO
2.60 - 3.00 (0.102 - 0.118) 1.50 - 1.75 (0.059 - 0.069) 0.00 - 0.15 (0.00 - 0.006) 0.90 - 1.45 (0.035 - 0.057) 2.80 - 3.00 (0.110 - 0.118) (NOTE 3)
0.35 - 0.55 (0.014 - 0.022)
0.09 - 0.20 (0.004 - 0.008) (NOTE 2)
NOTE: 1. DIMENSIONS ARE IN MILLIMETERS 2. DIMENSIONS ARE INCLUSIVE OF PLATING 3. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR 4. MOLD FLASH SHALL NOT EXCEED 0.254mm 5. PACKAGE EIAJ REFERENCE IS SC-74A (EIAJ)
This Material Copyrighted By Its Respective Manufacturer
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C3 1F
D1
70
VOUT 5V 300mA
65 60 55 50 45 0 100 200 400 300 LOAD CURRENT (mA) 500
243k FB 3 82.5k L2 10H C2 10F
1930 TA02a
1930 TA02b
4-Cell to 5V SEPIC Converter with Coupled Inductors
L1 10H C3 1F 1 SW LT1930 SHDN GND 2 C1: TAIYO-YUDEN X5R LMK212BJ225MG C2: TAIYO-YUDEN X5R JMK316BJ106ML C3: TAIYO-YUDEN X5R LMK212BJ105MG D1: ON SEMICONDUCTOR MBR0520 L1, L2: SUMIDA CLS62-100
1930 TA03
*
D1
VOUT 5V 300mA
243k FB 3 82.5k
*
L2 10H C2 10F
Dimensions in inches (millimeters) unless otherwise noted. S5 Package 5-Lead Plastic SOT-23
(LTC DWG # 05-08-1633)
0.35 - 0.50 0.90 - 1.30 (0.014 - 0.020) (0.035 - 0.051) FIVE PLACES (NOTE 2)
1.90 (0.074) REF
0.95 (0.037) REF
S5 SOT-23 0599
7
LT1930
TYPICAL APPLICATIO S
5V to 28V Boost Converter
L1 10H 5 C1 4.7F SHDN 4 VIN LT1930 SHDN GND 2 C1: TAIYO-YUDEN X5R EMK316BJ475ML C2: TAIYO-YUDEN X5R GMK325BJ225MN D1: ON SEMICONDUCTOR MBR0530 L1: SUMIDA CR43-100 FB 3 R2 75k 1 SW R1 1.58M C2 2.2F D1 VOUT 28V 100mA
VIN 3V to 6V
M1 C1 2.2F 5 VIN
RELATED PARTS
PART NUMBER LT1307 LT1316 LT1317 LT1610 LT1611 LT1613 LT1615 LT1617 LTC 1624
(R)
DESCRIPTION Single Cell Micropower 600kHz PWM DC/DC Converter Burst Mode Operation DC/DC Converter with Programmable Current Limit 2-Cell Micropower DC/DC Converter with Low-Battery Detector Single Cell Micropower DC/DC Converter Inverting 1.4MHz Switching Regulator in 5-Lead SOT-23 1.4MHz Switching Regulator in 5-Lead SOT-23 Micropower Constant Off-Time DC/DC Converter in 5-Lead SOT-23 Micropower Inverting DC/DC Converter in 5-Lead SOT-23 High Efficiency, N-Channel Switching Regulator Controller
TM
Burst Mode is a trademark of Linear Technology Corporation.
This Material Copyrighted By Its q Respective Manufacturer q
8
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408)432-1900 FAX: (408) 434-0507 www.linear-tech.com
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VIN 5V
1930 TA04
Boost Converter with Reverse Battery Protection
L1 4.7H 1 SW LT1930 SHDN 4 SHDN GND 2 C1: TAIYO-YUDEN X5R LMK432BJ226MM C2: TAIYO-YUDEN X5R LMK212BJ225MG D1: ON SEMICONDUCTOR MBR0520 L1: SUMIDA CR43-4R7 M1: SILICONIX Si6433DQ FB 3 R2 11.3k R1 60.4k D1 C3 47pF VOUT 8V 520mA AT VIN = 6V 240mA AT VIN = 3V
C2 22F
1930 TA05
COMMENTS 3.3V at 75mA from Single Cell, MSOP Package 1.5V Minimum, Precise Control of Peak Current Limit 3.3V at 200mA from 2 Cells, 600kHz Fixed Frequency 3V at 30mA from 1V, 1.7MHz Fixed Frequency - 5V at 150mA from 5V Input, Tiny SOT-23 Package 5V at 200mA from 3.3V Input, Tiny SOT-23 Package 20V at 12mA from 2.5V, Tiny SOT-23 Package -15V at 12mA from 2.5V Input, Tiny SOT-23 Package 95% DC, 3.5V to 36V VIN Range, SO-8
1930i LT/TP 0600 4K * PRINTED IN USA
(c) LINEAR TECHNOLOGY CORPORATION 2000

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