LT3501 LINER [Linear Technology], LT3501 Datasheet
LT3501
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LT3501 Summary of contents
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... SHDN pin the entire part can be placed in a low quiescent current shutdown mode. The LT3501 is available in a 20-lead TSSOP package with exposed leadframe for low thermal resistance. , LT, LTC, and LTM are registered trademarks of Linear Technology Corporation. ...
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... T V ......................................................................±1mA C1/2 Operating Junction Temperature Range LT3501EFE (Notes 2, 8) ..................... –40°C to 125°C LT3501IFE (Notes 2, 8) ...................... –40°C to 125°C Storage Temperature Range ................... –65°C to 150°C Lead Temperature (Soldering, 10 sec) .................. 300°C ELECTRICAL CHARACTERISTICS temperature range, otherwise specifi cations are at T unless otherwise specifi ...
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... The LT3501IFE is guaranteed and tested over the full –40°C to 125°C operating junction temperature range. Note 3: Minimum input voltage is defi ned as the voltage where internal ...
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... LT3501 ELECTRICAL CHARACTERISTICS Note 6: The IND to V maximum current is defi ned as the value of OUT current fl owing from the IND pin to the V pin which resets the switch OUT latch when the V pin is at its high clamp. C Note 7: This is the minimum voltage across the boost capacitor needed to guarantee full saturation of the internal power switch ...
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... FREQUENCY 175 170 1000 165 MINIMUM 500 160 SYNCHRONIZATION 155 FREQUENCY 150 0 125 –50 – TEMPERATURE (°C) LT3501 Power Good Threshold Voltage vs Temperature 800 780 760 740 RISING 720 700 FALLING 680 660 640 620 600 100 125 –50 0 ...
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... LT3501 TYPICAL PERFORMANCE CHARACTERISTICS External Sync Duty Cycle Range vs External Sync Frequency 100 90 MAXIMUM CLOCK 80 DUTY CYCLE MINIMUM CLOCK 20 DUTY CYCLE 10 0 250 500 1000 1250 750 1500 FREQUENCY (kHz) 3501 G17 Minimum Boost Voltage vs Temperature 2.5 2.0 1.5 1.0 0.5 0 –50 – ...
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... It is normally used for frequency compensa- tion, but can also be used as a current clamp or control loop override. If the error amplifi er drives V maximum switch current level, a voltage clamp activates. LT3501 Inductor Value vs Frequency for 3A Maximum Load Current 1500 L = 2.2µH 1250 L = 3.3µ ...
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... LT3501 PIN FUNCTIONS This indicates that the output is overloaded and current is pulled from the SS pin, reducing the regulation point. FB1/FB2 (Pins 17, 14): The FB pin is the negative input to the error amplifi er. The output switches regulate this pin to 0.8V, with respect to the exposed ground pad. Bias current fl ...
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... If the SHDN pin is taken below its 1.28V threshold the LT3501 will be placed in a low quiescent current mode. In this mode the LT3501 typically draws 9µA from V and <1µA from shutdown mode the PG is active IN2 with a typical sink capability of 50µ ...
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... LT3501 BLOCK DIAGRAM will be generated at the incoming frequency on the rising edge of the synchronization pulse with switch 1 in phase with the synchronization signal. In addition, the internal slope compensation will be automatically adjusted to pre- vent subharmonic oscillation during synchronization. The two regulators are constant frequency, current mode step-down converters ...
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... V R2 should be 10k or less to avoid bias current errors. Refer- ence designators refer to the Block Diagram in Figure 1. Choosing the Switching Frequency The LT3501 switching frequecy is set by resistor R3 in Figure 1. The R /SYNC pin is internally regulated at 0.975V. T Setting resistor R3 sets the current in the R which determines the oscillator frequency as illustrated in Figure 2 ...
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... MAX ( ) MIN Note that the LT3501 will regulate if the input voltage is taken above the calculated maximum voltage as long as maximum ratings of the V and BST pins are not violated. IN However operation in this region of input voltage will exhibit pulse skipping behavior ...
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... Then use these equations to check that the LT3501 will be able to deliver the required output current. Note again that these equations assume that the inductor current is continuous. ...
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... See Application Note 19 for more information. Input Capacitor Selection Bypass the inputs of the LT3501 circuit with a 4.7µF or higher ceramic capacitor of X7R or X5R type. A lower value or a less expensive Y5V type can be used if there is additional bypassing provided by bulk electrolytic or tantalum capacitors ...
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... The output capacitor fi lters the inductor current to generate an output with low voltage ripple. It also stores energy in order to satisfy transient loads and to stabilize the LT3501’s control loop. The switching frequency of the LT3501 deter- mines the value of output capacitance required. Also, the current mode control loop doesn’ ...
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... For proper start-up, the minimum input voltage is also limited by the boost circuit. If the input voltage is ramped slowly, or the LT3501 is turned on with its SS pin when the output is already in regulation, then the boost capacitor may not be fully charged. Because the boost capacitor is charged ...
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... The LT1375 data sheet contains a more thorough discus- sion of loop compensation and describes how to test the stability using a transient load. Figure 6 shows an equivalent circuit for the LT3501 control loop. The error amp is a transconductance amplifi er with fi nite output impedance. The power section, consisting of the modulator, power switch and inductor, is modeled as a transconductance amplifi ...
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... If the synchronization signal powers undetermined state ( the LT3501 as shown in Figure 7. The circuit as shown will isolate the synchronization signal when the output voltage is below 90% of the regulated output. The LT3501 will start-up with a switching frequency determined by the resistor from the R ...
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... SHDN pin should be bypassed with a 1nF capacitor to prevent coupling problems from the switch node. Soft-Start The output of the LT3501 regulates to the lowest voltage present at either the SS pin or an internal 0.8V reference. A capacitor from the SS pin to ground is charged – ...
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... V Output Tracking/Sequencing Complex output tracking and sequencing between chan- pin is pulled C nels can be implemented using the LT3501’s SS and PG pins. Figure 9 shows several confi gurations for output tracking/sequencing for a 3.3V and 1.8V application. pin is re- C Independent soft-start for each channel is shown in Figure 9a ...
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... V OUT1 + EXTERNAL – SOURCE PG1 1.8V V OUT2 PG2 Figure 9 LT3501 Absolute Start-Up V OUT1 0.5V/DIV PG1 V OUT2 0.5V/DIV PG2 10ms/DIV 3.3V SS1 V OUT1 0.22µF LT3501 PG1 1.8V SS2 V OUT2 PG2 R1 13.7k R2 8.08k (9c) V OUT1 0.5V/DIV PG1 V OUT2 0.5V/DIV SS1/2 10ms/DIV 3.3V SS1 V OUT1 LT3501 PG1 1.8V SS2 ...
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... L V • 4.7µF PMEG4005 V V IN1 IN2 26.7k SHDN FSET BST1 BST2 0.47µF SW1 SW2 B360A LT3501 IND1 IND2 V V OUT1 OUT2 PG1 PG2 FB1 FB2 SS/TRACK1 SS/TRACK2 470pF GND 40.2k 0.1µF Single Step Down: Frequency must be ...
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... Thermal Considerations The PCB must also provide heat sinking to keep the LT3501 cool. The exposed metal on the bottom of the package must be soldered to a ground plane. This ground should be tied to other copper layers below with thermal vias; these layers will spread the heat dissipated by the Figure 12 ...
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... IC sees as ambient temperature. See the LT1767 data sheet’s Thermal Considerations section. Single, Low Ripple 6A Output The LT3501 can generate a single, low ripple 6A output if the outputs of the two switching regulators are tied together and share a single output capacitor. By tying the two FB pins together and the two V two channels will share the load current ...
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... SW1 SW2 B360A LT3501 IND1 IND2 V V OUT1 OUT2 100k PG1 PG2 FB1 FB2 SS/TRACK1 SS/TRACK2 1000pF GND 22pF 17.8k 0.1µF LT3501 26.7k 2.2µH PMEG4005 B360A V OUT2 2.5V 47µF 100k 16.9k 470pF 10pF 40.2k 8.06k 3501 TA02 20.5k 1.5µH 0.47µF B360A PMEG4005 C2 3501 TA03 3501fb 25 ...
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... LT3501 TYPICAL APPLICATIONS PMEG4005 V OUT1 3.3V 6A 47µF 24.9k ×2 8.06k Dual LT3501 Synchronized 3.3V/12A Output, 3MHz Effective Switch Frequency V IN 5.5V TO 24V 10µF PMEG4005 V OUT1 3.3V 26 1.25MHz Single 3.3V/6A Low Ripple Output V 4. 4.7µF 1µ IN1 IN2 SHDN R /SYNC T PMEG4005* BST1 BST2 1.5µH 0.47µ ...
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... BSC 0.195 – 0.30 (.0077 – .0118) 4. RECOMMENDED MINIMUM PCB METAL SIZE FOR EXPOSED PAD ATTACHMENT MILLIMETERS (INCHES) *DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.150mm (.006") PER SIDE LT3501 6.40 – 6.60* (.252 – .260) 4.95 (.195 6.40 2.74 (.252) ( ...
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... LT3501 RELATED PARTS PART NUMBER DESCRIPTION LT1766 60V, 1. 200kHz High Effi ciency Step-Down DC/DC OUT Converter LT1933 500mA (I ), 500kHz Step-Down Switching Regulator in OUT SOT-23 LT1936 36V, 1. 500kHz High Effi ciency Step-Down DC/DC OUT Converter LT1940 Dual 25V, 1. 1.1MHz High Effi ciency Step-Down OUT ...