LT1913 LINER | Alldatasheet
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25V, 3.5A, 2.4MHz Step-Down Switching Regulator The L T®1913 is an adjustable frequency (200kHz to 2.4MHz) monolithic buck switching regulator that accepts input voltages up to 25V . A high effi ciency 95m switch is included on the die along with a boost Schottky diode and the necessary oscillator , control, and logic circuitry. Current mode topology is used for fast transient response and good loop stability. Shutdown reduces input supply current to less than 1μA while a resistor and capacitor on the RUN/SS pin provide a controlled output voltage ramp (soft-start). A power good fl ag signals when V OUT reaches 91% of the programmed output voltage. The L T1913 is available in 10-Pin 3mm × 3mm DFN packages with ex- posed pads for low thermal resistance. ■ Automotive Battery Regulation ■ Power for Portable Products ■ Distributed Supply Regulation ■ Industrial Supplies ■ Wall T ransformer Regulation ■ Wide Input Range: 3.6V to 25V ■ 3.5A Maximum Output Current ■ Adjustable Switching Frequency: 200kHz to 2.4MHz ■ Low Shutdown Current: IQ < 1μA ■ Integrated Boost Diode ■ Synchronizable Between 250kHz to 2MHz ■ Power Good Flag ■ Saturating Switch Design: 95m On-Resistance ■ 0.790V Feedback Reference Voltage ■ Output Voltage: 0.79V to 25V ■ Thermal Protection ■ Soft-Start Capability ■ Small 10-Pin (3mm × 3mm) DFN Packages 5V Step-Down Converter APPLICATIO SU FEATURES DESCRIPTIO U TYPICAL APPLICATIO U SW FB VC PG RT VIN BD VIN 6.5V TO 25V VOUT 3.5A 10μF 0.47μF 680pF 47μF100k 15k 63.4k 4.7μH 536k GND OFF ON L T1913
1913 TA01a
Effi ciency , L T , L TC and L TM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. OUTPUT CURRENT (A) 0 0.5 EFFICIENCY (%) 100 1 2 2.5
1913 G01
1.5 3 3.5 VIN = 12V VOUT = 5V L = 4.7μH f = 600kHz VIN = 24V
ELECTRICAL CHARACTERISTICS
FB, RT , V (Note 1) PARAMETER CONDITIONS MIN TYP MAX UNITS Minimum Input Voltage ● 3 3.6 V Quiescent Current from VIN VRUN/SS = 0.2V 0.01 0.5 μA VBD = 3V , Not Switching ● 0.45 1.2 mA VBD = 0, Not Switching 1.3 2.3 mA Quiescent Current from BD VRUN/SS = 0.2V 0.01 0.5 μA VBD = 3V , Not Switching ● 0.9 1.8 mA VBD = 0, Not Switching 11 0 μA Minimum Bias V oltage (BD Pin) 2.7 3 V The ● denotes the specifi cations which apply over the full operating temperature range, otherwise specifi cations are at TA = 25°C. VIN = 10V , VRUN/SS = 10V , VBOOST = 15V , VBD = 3.3V unless otherwise noted. (Note 2) ABSOLUTE AXI U RATI GSW WW U Operating Junction Temperature Range (Note 2) TOP VIEW DD PACKAGE 10-LEAD (3mm × 3mm) PLASTIC DFN 3 11 1 RT VC FB PG SYNC BD BOOST SW V IN RUN/SS θJA = 45°C/W , θJC = 10°C/W EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB PIN CONFIGURATION ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE L T1913EDD#PBF L T1913EDD#TRPBF LDJW 10-Lead (3mm × 3mm) Plastic DFN –40°C to 125°C L T1913IDD#PBF L T1913IDD#TRPBF LDJW 10-Lead (3mm × 3mm) Plastic DFN –40°C to 125°C Consult L TC Marketing for parts specifi ed with wider operating temperature ranges. *The temperature grade is identifi ed by a label on the shipping container . Consult L TC Marketing for information on non-standard lead based fi nish parts. For more information on lead free part marking, go to: http://www.linear .com/leadfree/ For more information on tape and reel specifi cations, go to: http://www.linear .com/tapeandreel/
PARAMETER CONDITIONS MIN TYP MAX UNITS Feedback Voltage 780 775 790 790 800 805 mV mV FB Pin Bias Current (Note 3) V FB = 0.8V , VC = 0.4V ● 10 40 nA FB Voltage Line Regulation 4V < V IN < 25V 0.002 0.01 %/V Error Amp gm 525 μMho Error Amp Gain 2000 VC Source Current 60 μA VC Sink Current 60 μA VC Pin to Switch Current Gain 5.3 A/V VC Clamp Voltage 2.0 V Switching Frequency R T = 8.66k RT = 29.4k RT = 187k 2.2 1.0 200 2.45 1.1 230 2.7 1.25 260 MHz MHz kHz Minimum Switch Off-Time ● 60 150 nS Switch Current Limit Duty Cycle = 5% 4.6 5.4 6.0 A Switch V CESAT ISW = 3.5A 335 mV Boost Schottky Reverse Leakage V SW = 10V , VBD = 0V 0.02 2 μA Minimum Boost Voltage (Note 4) ● 1.5 2.0 V BOOST Pin Current I SW = 1A 35 60 mA RUN/SS Pin Current V RUN/SS = 2.5V 5 8 μA RUN/SS Input Voltage High 2.5 V RUN/SS Input Voltage Low 0.2 V PG Threshold Offset from Feedback Voltage V FB Rising 65 mV PG Hysteresis 10 mV PG Leakage V PG = 5V 0.1 1 μA PG Sink Current V PG = 0.4V ● 200 800 μA SYNC Low Threshold 0.5 V SYNC High Threshold 0.8 V SYNC Pin Bias Current V SYNC = 0V 0.1 μA 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 L T1913E is guaranteed to meet performance specifi cations from 0°C to 125°C. Specifi cations over the –40°C to 125°C operating temperature range are assured by design, characterization and correlation with statistical process controls. The L T1913I specifi cations are guaranteed over the –40°C to 125°C temperature range. Note 3: Bias current fl ows out of the FB pin. Note 4: This is the minimum voltage across the boost capacitor needed to guarantee full saturation of the switch. The ● denotes the specifi cations which apply over the full operating temperature range, otherwise specifi cations are at TA = 25°C. VIN = 10V , VRUN/SS = 10V , VBOOST = 15V , VBD = 3.3V unless otherwise noted. (Note 2)
OUTPUT CURRENT (A) 0 0.5 EFFICIENCY (%) 100 1 2 2.5 1.5 3 3.5 VIN = 12V VOUT = 5V L = 4.7μH f = 600kHz VIN = 24V OUTPUT CURRENT (A) 0 0.5 EFFICIENCY (%) 100 1 2 2.5
1913 G02
1.5 3 3.5 VIN = 12V VOUT = 3.3V L = 3.3μH f = 600kHz VIN = 24V Effi ciency Effi ciency INPUT VOL TAGE (V) LOAD CURRENT (A)
1913 G06
4.0 10 20 3.0 2.5 5.5 5.0 4.5 3.5 TYPICAL MINIMUM VOUT = 3.3V TA = 25°C L = 4.7μH f = 600kHz Maximum Load Current DUTY CYCLE (%) SWITCH CURRENT LIMIT(A)
1913 G08
4.5 20 60 3.5 3.0 6.0 5.5 5.0 4.0 80 100 Switch Current Limit TYPICAL PERFOR A CE CHARACTERISTICSUW SWITCH CURRENT (A) BOOST PIN CURRENT (mA) 120
1913 G11
TEMPERATURE (°C) SWITCH CURRENT LIMIT (A) 4.0 4.5 5.5 5.0
1913 G09
3.5 3.0 2.0 2.5 6.5 6.0 DUTY CYCLE = 10 % DUTY CYCLE = 90 % –50 25–25 0 50 75 100 150 125 Switch Current Limit INPUT VOL TAGE (V) LOAD CURRENT (A)
1913 G07
4.5 10 20 3.5 3.0 5.5 5.0 4.0 TYPICAL MINIMUM VOUT = 5V TA = 25°C L = 4.7μH f = 600kHz Maximum Load Current SWITCH CURRENT (A) 400 500 700
1913 G10
600VOL TAGE DROP (mV) Switch Voltage Drop Effi ciency TA = 25°C unless otherwise noted. OUTPUT CURRENT (A) 0 0.5 EFFICIENCY (%) TOTAL POWER LOSS (W) 100 1 2 2.5
1913 G03
0.5 1.5 3.0 1.0 2.5 2.0 1.5 3 3.5 VIN = 12V VOUT = 5V L = 4.7μH f = 600kHz
TEMPERATURE (°C) FEEDBACK VOL TAGE (mV) 800
1913 G12
–50 25–25 0 50 75 100 150 125 Feedback Voltage TEMPERATURE (°C) FREQUENCY (MHz) 1.00 1.10
1913 G13
0.90 0.80 1.20 0.95 1.05 0.85 1.15 –50 25–25 0 50 75 100 150 125 RT = 34.0k Switching Frequency FB PIN VOL TAGE (mV) SWITCHING FREQUENCY (kHz) 800 1000 1200 600
1913 G14
200 400 800500100 300 700 900 200 RT = 34.0k Frequency Foldback TEMPERATURE (°C) MINIMUM SWITCH ON TIME (ns) 100 120
1913 G15
–50 25–25 0 50 75 100 15 0125 Minimum Switch On-Time RUN/SS PIN VOL TAGE (V) SWITCH CURRENT LIMIT (A) 1.5
1913 G16
0.5 1 2 2.5 3 3.5 Soft-Start RUN/SS PIN VOL TAGE (V) RUN/SS PIN CURRENT (μA) 15 25
1913 G17
BOOST DIODE CURRENT (A) BOOST DIODE VF (V) 0.8 1.0 1.2 2.0
1913 G18
0.6 0.4 0.5 1.0 1.5 0.2 1.4 Boost Diode TYPICAL PERFOR A CE CHARACTERISTICSUW TA = 25°C unless otherwise noted. FB PIN ERROR VOL TAGE (mV) –200 –50 VC PIN CURRENT (μA) –20 02 0 0
1913 G19
–40 –100 100 –10 –30 Error Amp Output Current LOAD CURRENT (mA) INPUT VOL TAGE (V)3.0 3.5 10000
1913 G20
2.5 2.0 10 100 1000 5.0 4.5 4.0 VOUT = 3.3V TA = 25°C L = 4.7μH f = 600kHz Minimum Input Voltage
LOAD CURRENT (mA) INPUT VOL TAGE (V) 5.0 5.5
1913 G21
4.5 4.0 6.5 6.0 VOUT = 5V TA = 25 °C L = 4.7μH f = 600kHz Minimum Input Voltage TEMPERATURE (°C) VC VOL TAGE (V) 1.50 2.00 2.50
1913 G22
1.00 0.50 CURRENT LIMIT CLAMP SWITCHING THRESHOLD –50 25–25 0 50 75 100 150 125 TEMPERATURE (°C) THRESHOLD VOL TAGE (%)
1913 G23
–50 25–25 0 50 75 100 150 125
1913 G25
0.2A/DIV VSW 5V/DIV VOUT 10mV/DIV VIN = 12V VOUT = 3.3V ILOAD = 110mA 1μs/DIV Switching Waveforms; Discontinuous Operation Power Good Threshold
1913 G26
0.5A/DIV VSW 5V/DIV VOUT 10mV/DIV VIN = 12V VOUT = 3.3V ILOAD = 1A 1μs/DIV Switching Waveforms; Continuous Operation VC Voltages TYPICAL PERFOR A CE CHARACTERISTICSUW TA = 25°C unless otherwise noted.
BD (Pin 1): This pin connects to the anode of the boost Schottky diode. BD also supplies current to the internal regulator . BOOST (Pin 2): This pin is used to provide a drive voltage, higher than the input voltage, to the internal bipolar NPN power switch. SW (Pin 3): The SW pin is the output of the internal power switch. Connect this pin to the inductor , catch diode and boost capacitor . V IN (Pin 4): The VIN pin supplies current to the L T1913’s internal regulator and to the internal power switch. This pin must be locally bypassed. RUN/SS (Pin 5): The RUN/SS pin is used to put the L T1913 in shutdown mode. Tie to ground to shut down the L T1913. Tie to 2.5V or more for normal operation. If the shutdown feature is not used, tie this pin to the V IN pin. RUN/SS also provides a soft-start function; see the Applications Information section. SYNC (Pin 6): This is the external clock synchronization input. Ground this pin when not used. Tie to a clock source for synchronization. Clock edges should have rise and fall times faster than 1μs. Do not leave pin fl oating. See synchronizing section in Applications Information. PG (Pin 7): The PG pin is the open collector output of an internal comparator . PG remains low until the FB pin is within 9% of the fi nal regulation voltage. PG output is valid when V IN is above 3.6V and RUN/SS is high. FB (Pin 8): The L T1913 regulates the FB pin to 0.790V . Connect the feedback resistor divider tap to this pin. VC (Pin 9): The VC pin is the output of the internal error amplifi er . The voltage on this pin controls the peak switch current. Tie an RC network from this pin to ground to compensate the control loop. RT (Pin 10): Oscillator Resistor Input. Connecting a resistor to ground from this pin sets the switching frequency. Exposed Pad (Pin 11): Ground. The Exposed Pad must be soldered to PCB.
200kHz TO 2.4MHz VC CLAMP SOFT-START SLOPE COMP R VINVIN RUN/SS BOOST SW SWITCH LATCH VC VOUT CF CC RC BD RT GND ERROR AMP FB RT PG 0.7V S Q 1913 BD 11 8 INTERNAL 0.79V REF SYNC
The L T1913 is a constant frequency, current mode step- down regulator . An oscillator , with frequency set by RT , enables an RS fl ip-fl op, turning on the internal power switch. An amplifi er and comparator monitor the current fl owing between the V IN and SW pins, turning the switch off when this current reaches a level determined by the voltage at V C. An error amplifi er measures the output voltage through an external resistor divider tied to the FB pin and servos the V C pin. If the error amplifi er’s output increases, more current is delivered to the output; if it decreases, less current is delivered. An active clamp on the V C pin provides current limit. The VC pin is also clamped to the voltage on the RUN/SS pin; soft-start is implemented by generating a voltage ramp at the RUN/SS pin using an external resistor and capacitor . An internal regulator provides power to the control circuitry. The bias regulator normally draws power from the V IN pin, but if the BD pin is connected to an external voltage higher than 3V bias power will be drawn from the external source (typically the regulated output voltage). This improves effi ciency. The RUN/SS pin is used to place the L T1913 in shutdown, disconnecting the output and reducing the input current to less than 0.5μA. The switch driver operates from either the input or from the BOOST pin. An external capacitor and diode are used to generate a voltage at the BOOST pin that is higher than the input supply. This allows the driver to fully saturate the internal bipolar NPN power switch for effi cient opera- tion. The oscillator reduces the L T1913’s operating frequency when the voltage at the FB pin is low. This frequency foldback helps to control the output current during startup and overload. The L T1913 contains a power good comparator which trips when the FB pin is at 91% of its regulated value. The PG output is an open-collector transistor that is off when the output is in regulation, allowing an external resistor to pull the PG pin high. Power good is valid when the L T1913 is enabled and V IN is above 3.6V . OPERATION
Reference designators refer to the Block Diagram. Figure 1. Switching Frequency vs. RT Value minimum of ~150ns and turn off for a minimum of ~150ns. the inductor and capacitor values small.
be higher than in normal operation. maximum duty cycle (see equation in previous section). switching frequency should be used. and switching frequency will determine the ripple current. must be lower than the L T1913’s switch current limit (ILIM). suffi cient maximum output current (IOUT(MAX)). material should be intended for high frequency applications. Table 1 lists several vendors and suitable types. Table 1. Inductor Vendors
load is lower than 3.5A, then you can decrease the value of the inductor and operate with higher ripple current. This allows you to use a physically smaller inductor , or one with a lower DCR resulting in higher effi ciency. There are several graphs in the Typical Performance Characteristics section of this data sheet that show the maximum load current as a function of input voltage and inductor value for several popular output voltages. Low inductance may result in discontinuous mode operation, which is okay but further reduces maximum load current. For details of maximum output current and discontinuous mode opera- tion, see Linear Technology Application Note 44. Finally, for duty cycles greater than 50% (V OUT/VIN > 0.5), there is a minimum inductance required to avoid subharmonic oscillations. See AN19. Input Capacitor Bypass the input of the L T1913 circuit with a ceramic capacitor of X7R or X5R type. Y5V types have poor performance over temperature and applied voltage, and should not be used. A 10μF to 22μF ceramic capacitor is adequate to bypass the L T1913 and will easily handle the ripple current. Note that larger input capacitance is required when a lower switching frequency is used. If the input power source has high impedance, or there is signifi cant inductance due to long wires or cables, additional bulk capacitance may be necessary. This can be provided with a lower performance electrolytic capacitor . Step-down regulators draw current from the input sup- ply in pulses with very fast rise and fall times. The input capacitor is required to reduce the resulting voltage ripple at the L T1913 and to force this very high frequency switching current into a tight local loop, minimizing EMI. A 10μF capacitor is capable of this task, but only if it is placed close to the L T1913 and the catch diode (see the PCB Layout section). A second precaution regarding the ceramic input capacitor concerns the maximum input voltage rating of the L T1913. A ceramic input capacitor combined with trace or cable inductance forms a high quality (under damped) tank circuit. If the L T1913 circuit is plugged into a live supply, the input voltage can ring to twice its nominal value, possibly exceeding the L T1913’s voltage rating. This situation is easily avoided (see the Hot Plugging Safety section). For space sensitive applications, a 4.7μF ceramic capaci- tor can be used for local bypassing of the L T1913 input. However , the lower input capacitance will result in in- creased input current ripple and input voltage ripple, and may couple noise into other circuitry. Also, the increased voltage ripple will raise the minimum operating voltage of the L T1913 to ~3.7V . Output Capacitor and Output Ripple The output capacitor has two essential functions. Along with the inductor , it fi lters the square wave generated by the L T1913 to produce the DC output. In this role it determines the output ripple, and low impedance at the switching frequency is important. The second function is to store energy in order to satisfy transient loads and stabilize the L T1913’s control loop. Ceramic capacitors have very low equivalent series resistance (ESR) and provide the best ripple performance. A good starting value is: COUT = 100 VOUT fSW where f SW is in MHz, and C OUT is the recommended output capacitance in μF . Use X5R or X7R types. This choice will provide low output ripple and good transient response. T ransient performance can be improved with a higher value capacitor if the compensation network is also adjusted to maintain the loop bandwidth. A lower value of output capacitor can be used to save space and cost but transient performance will suffer . See the Frequency Compensation section to choose an appropriate compen- sation network. When choosing a capacitor , look carefully through the data sheet to fi nd out what the actual capacitance is under operating conditions (applied voltage and temperature). A physically larger capacitor , or one with a higher voltage APPLICATIONS INFORMATION
electrolytic capacitors can be used for the output capacitor . 3 lists several Schottky diodes and their manufacturers. Table 3. Diode Vendors Table 2. Capacitor Vendors
output capacitor has high ESR. transconductance amplifi er with fi nite output impedance. the feedback divider may improve the transient response. rent is stepped from 1A to 3A and back to 1A.
1913 F02
Figure 3. T ransient Load Response of the L T1913 Front Page Application as the Load Current is Stepped from 1A to 3A. Figure 2. Model for Loop Response
1913 F03
Figure 5. The Minimum Input Voltage Depends on
1913 F05
5.5 TO START
1913 FO4
Figure 4. Three Circuits For Generating The Boost Voltage pin quiescent current comes from a lower voltage source. of the BOOST and BD pins are not exceeded.
250kHz and higher , the RT should be chosen for 200kHz. input voltage to maintain regulation. reducing the maximum input current during start-up. up and shut-down waveforms with the soft-start circuit. and peaks that are above 0.8V (up to 6V). Figure 6. To Soft-Start the L T1913, Add a Resisitor
1913 F06
protects against a shorted or reversed input. a local, unbroken ground plane below these components. The SW and BOOST nodes should be as small as possible. traces will shield them from the SW and BOOST nodes. Figure 7. Diode D4 Prevents a Shorted Input from
1913 F07
1913 F08
Figure 8. A Good PCB Layout Ensures Proper , Low EMI Operation board and on the bottom side.
a 5V output at full load operating from 24V . Figure 9. A Well Chosen Input Network Prevents Input Voltage Overshoot and
1913 F09
100 LFPM airfl ow, this resistance can fall by another 25%.
sistance. Because of the large output current capability of the L T1913, it is possible to dissipate enough heat to raise the junction temperature beyond the absolute maximum of 125°C. When operating at high ambient temperatures, the maximum load current should be derated as the ambient temperature approaches 125°C. Power dissipation within the L T1913 can be estimated by calculating the total power loss from an effi ciency measure- ment and subtracting the catch diode loss and inductor loss. The die temperature is calculated by multiplying the L T1913 power dissipation by the thermal resistance from junction to ambient. Other Linear Technology Publications Application Notes 19, 35 and 44 contain more detailed descriptions and design information for buck regulators and other switching regulators. The L T1376 data sheet has a more extensive discussion of output ripple, loop compensation and stability testing. Design Note 100 shows how to generate a bipolar output supply using a buck regulator . APPLICATIONS INFORMATION 5V Step-Down Converter SW FB VC PG RT VIN BD VIN 6.5V TO 25V VOUT 3.5A 10μF 0.47μF 47μF100k f = 600kHz D: ON SEMI MBRA340 L: NEC MPLC0730L4R7 D 15k 63.4k L 4.7μH 536k GND 680pF ON OFF LT1913
1913 TA02
3.3V Step-Down Converter SW FB VC PG RT VIN BD VIN 4.8V TO 25V VOUT 3.3V 3.5A 4.7μF 0.47μF 47μF100k f = 600kHz D: ON SEMI MBRA340 L: NEC MPLC0730L3R3 D 19k 63.4k L 3.3μH GND 680pF ON OFF L T1913
1913 TA03
2.5V Step-Down Converter SW FB VC PG RT VIN BD VIN 4V TO 25V VOUT 2.5V 3.5A 4.7μF 1μF 47μF100k f = 600kHz D1: ON SEMI MBRA340 D2: MBR0540 L: NEC MPLC0730L3R3 15.4k 63.4k L 3.3μH 215k GND 680pF ON OFF L T1913
1913 TA04
3.5A 10μF 0.47μF 47μF50k f = 600kHz D: ON SEMI MBRA340 L: NEC MBP107558R2P D 17.4k 63.4k L 8.2μH GND 680pF ON OFF L T1913
1913 TA06
5V , 2MHz Step-Down Converter SW FB VC PG RT VIN BD VIN 8.6V TO 22V VOUT 2.5A 4.7μF 0.47μF 22μF100k f = 2MHz D: ON SEMI MBRA340 L: NEC MPLC0730L2R2 D 15k 12.7k L 2.2μH GND 680pF ON OFF L T1913
1913 TA05
1.8V Step-Down Converter SW FB VC PG RT VIN BD VIN 3.6V TO 25V VOUT 1.8V 3.5A 4.7μF 0.47μF 47μF100k f = 500kHz D: ON SEMI MBRA340 L: NEC MPLC0730L3R3 D 16.9k 78.7k L 3.3μH 127k GND 680pF ON OFF L T1913
1913 TA08
10-Lead Plastic DFN (3mm × 3mm) (Reference L TC DWG # 05-08-1699) PACKAGE DESCRIPTION 3.00 ±0.10 (4 SIDES) NOTE: 1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-2). CHECK THE LTC WEBSITE DATA SHEET FOR CURRENT STATUS OF VARIATION ASSIGNMENT 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE 0.38 ± 0.10 BOTTOM VIEW—EXPOSED PAD 1.65 ± 0.10 (2 SIDES) 0.75 ±0.05 R = 0.115 TYP 2.38 ±0.10 (2 SIDES) 106 PIN 1 TOP MARK (SEE NOTE 6)
0.200 REF
0.00 – 0.05 (DD) DFN 1103 0.25 ± 0.05 2.38 ±0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS 1.65 ±0.05 (2 SIDES)2.15 ±0.05 0.50 BSC 0.675 ±0.05 3.50 ±0.05 PACKAGE OUTLINE 0.25 ± 0.05
0.50 BSC
Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear .com © LINEAR TECHNOLOGY CORPORATION 2007 LT 1207 • PRINTED IN USA PART NUMBER DESCRIPTION COMMENTS L T1766 60V , 1.2A (I OUT), 200kHz, High Effi ciency Step-Down DC/DC Converter VIN: 5.5V to 60V , VOUT(MIN) = 1.2V , IQ = 2.5mA, ISD = 25μA, TSSOP16/E Package L T1933 500mA (I OUT), 500kHz Step-Down Switching Regulator in SOT-23 V IN: 3.6V to 36V , VOUT(MIN) = 1.2V , IQ = 1.6mA, ISD < 1μA, ThinSOTTM Package L T1936 36V , 1.4A (I OUT), 500kHz, High Effi ciency Step-Down DC/DC Converter VIN: 3.6V to 36V , VOUT(MIN) = 1.2V , IQ = 1.9mA, ISD < 1μA, L T1940 Dual 25V , 1.4A (I OUT), 1.1MHz, High Effi ciency Step-Down DC/DC Converter VIN: 3.6V to 25V , VOUT(MIN) = 1.2V , IQ = 3.8mA, ISD < 30μA, L T1976/L T1967 60V , 1.2A (IOUT), 200kHz/500kHz, High Effi ciency Step-Down DC/DC Converters with Burst Mode Operation VIN: 3.3V to 60V , VOUT(MIN) = 1.2V , IQ = 100μA, ISD < 1μA, L T3434/L T3435 60V , 2.4A (IOUT), 200kHz/500kHz, High Effi ciency Step-Down DC/DC Converters with Burst Mode Operation VIN: 3.3V to 60V , VOUT(MIN) = 1.2V , IQ = 100μA, ISD < 1μA, L T3437 60V , 400mA (I OUT), Micropower Step-Down DC/DC Converter with Burst Mode Operation VIN: 3.3V to 60V , VOUT(MIN) = 1.25V , IQ = 100μA, ISD < 1μA, 3mm × 3mm DFN10 and TSSOP16E Packages L T3480 36V with T ransient Protection to 60V , 2A (I OUT), 2.4MHz, High Effi ciency Step-Down DC/DC Converter with Burst Mode Operation VIN: 3.6V to 38V , VOUT(MIN) = 0.78V , IQ = 70μA, ISD < 1μA, 3mm × 3mm DFN10 and MSOP10E Packages L T3481 34V with T ransient Protection to 36V , 2A (I OUT), 2.8MHz, High Effi ciency Step-Down DC/DC Converter with Burst Mode Operation VIN: 3.6V to 34V , VOUT(MIN) = 1.26V , IQ = 50μA, ISD < 1μA, 3mm × 3mm DFN10 and MSOP10E Packages L T3493 36V , 1.4A (I OUT), 750kHz High Effi ciency Step-Down DC/DC Converter VIN: 3.6V to 36V , VOUT(MIN) = 0.8V , IQ = 1.9mA, ISD < 1μA, 2mm × 3mm DFN6 Package L T3505 36V with T ransient Protection to 40V , 1.4A (I OUT), 3MHz, High Effi ciency Step-Down DC/DC Converter VIN: 3.6V to 34V , VOUT(MIN) = 0.78V , IQ = 2mA, ISD = 2μA, 3mm × 3mm DFN8 and MSOP8E Packages L T3508 36V with T ransient Protection to 40V , Dual 1.4A (I OUT), 3MHz, High Effi ciency Step-Down DC/DC Converter VIN: 3.7V to 37V , VOUT(MIN) = 0.8V , IQ = 4.6mA, ISD = 1μA, 4mm × 4mm QFN24 and TSSOP16E Packages L T3680 36V , 3.5A(I OUT), 2.4MHz High Effi ciency Step-Down DC/DC Converter VIN: 3.6V to 36V , VOUT(MIN) = 0.79V , IQ = 75μA, ISD < 1μA, 3mm × 3mm DFN, MSOP10E L T3684 34V with T ransient Protection to 36V , 2A (I OUT), 2.8MHz, High Effi ciency Step-Down DC/DC Converter VIN: 3.6V to 34V , VOUT(MIN) = 1.26V , IQ = 850μA, ISD < 1μA, 3mm × 3mm DFN10 and MSOP10E Packages L T3685 36V with T ransient Protection to 60V , Dual 2A (I OUT), 2.4MHz, High Effi ciency Step-Down DC/DC Converter VIN: 3.6V to 38V , VOUT(MIN) = 0.78V , IQ = 70μA, ISD < 1μA, 3mm × 3mm DFN10 and MSOP10E Packages TYPICAL APPLICATIO U RELATED PARTS SW FB VC PG RT VIN BD VIN 3.6V TO 25V VOUT 1.2V 3.5A 4.7μF 0.47μF 100μF f = 500kHz D: ON SEMI MBRA340 L: NEC MPLC0730L3R3 D 17k 78.7k L 3.3μH GND 470pF ON OFF L T1913
1913 TA09
52.3k 1.2V Step-Down Converter