LT3505 LINER [Linear Technology], LT3505 Datasheet
LT3505
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LT3505 Summary of contents
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FeaTures Wide Input Range: 3.1V to 25V n Two Switching Regulators with 3A Output Capability n Independent Supply to Each Regulator n Adjustable/Synchronizable Fixed Frequency n Operation from 250kHz to 1.5MHz Antiphase Switching n Outputs Can be Paralleled n Independent, ...
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LT3501 absoluTe MaxiMuM raTings (Note SHDN, PG1/2 ...................................... 25V/–0.3V IN1/2 SW1/2 ....................................................................V BST1/2 ........................................................... 35V/–0.3V BST1/2 Pins Above SW1/2 ........................................25V IND1/2 ......................................................................±5A V ........................................................ V OUT1/2 FB1/2, SS1/2, R /SYNC ............................................5. ...................................................................... ±1mA C1/2 Operating ...
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T unless otherwise specified. PARAMETER Feedback Bias Current Ch 1/Ch 2 Error Amplifier Error Amplifier Gain Ch 1/Ch 2 Error Amplifier to Switch Gain Ch 1/Ch 2 ...
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LT3501 elecTrical characTerisTics Note 4: An internal power-on reset (POR) latch is set on the positive transition of the SHDN pin through its threshold. The output of the latch activates current sources on each SS pin which typically sink 1.5mA, ...
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Typical perForMance characTerisTics Soft-Start to Feedback Offset Voltage vs Temperature –1 –2 –3 –4 –50 – 100 125 TEMPERATURE (°C) 3501 G08 Power Good Sink Current vs Temperature 1000 950 900 ...
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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 0 250 500 750 1000 1250 1500 FREQUENCY (kHz) ...
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Typical perForMance characTerisTics Dropout Operation 6 LOAD = OUT 3.3V OUT 2 FREQUENCY 1 1.5MHz 250kHz 0 4 2.5 3 3.5 4 5.5 6 INPUT VOLTAGE (V) 3501 G27 ...
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LT3501 pin FuncTions V (Pin 1): The V pin powers the internal control IN1 IN1 circuitry for both channels and is monitored by the under- voltage lockout comparator. The V IN1 to the collector of channel 1’s on-chip power NPN ...
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FuncTions the clock signal is detected, with switch 1 in phase with the synchronization signal. Each rising clock edge initiates an oscillator ramp reset. A gain control loop servos the oscillator charging current to maintain a constant oscillator amplitude. ...
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LT3501 block DiagraM R /SYNC IN1 INTERNAL REGULATOR AND REFERENCE 3µA 7µA SHDN + – + SHUTDOWN 1.28V COMPARATOR POR UNDERVOLTAGE TSD SOFT-START GND COMPARATOR Figure 1. Block Diagram (One of Two Switching Regulators Shown) The LT3501 ...
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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 ...
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LT3501 applicaTions inForMaTion Choosing the Output Voltage The output voltage is programmed with a resistor divider between the output and the FB pin. Choose the 1% resis- tors according to: V OUT R1= R2 • – 1 ...
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The duty cycle is the fraction of time that the internal switch is on during a clock cycle. Unlike fixed frequency regulators, the LT3501 will not switch off at the end of each clock cycle if ...
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LT3501 applicaTions inForMaTion and its saturation current should be about 30% higher. To keep efficiency high, the series resistance (DCR) should be less than 0.05Ω. For applications with a duty cycle of about 50%, the induc- tor value should be ...
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For details of maximum output current and discontinuous mode operation, see Linear Technology Application Note 44. Finally, for duty cycles greater than 50% ...
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LT3501 applicaTions inForMaTion either clamp the input voltage or dampen the tank circuit by adding a lossy capacitor in parallel with the ceramic capacitor. For details, see Application Note 88. Output Capacitor Selection Typically step-down regulators are easily compensated with ...
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Table 2 VENDOR TYPE Taiyo Yuden Ceramic X5R, X7R AVX Ceramic X5R, X7R Tantalum Kemet Tantalum TA Organic AL Organic Sanyo TA/AL Organic Panasonic AL Organic TDK Ceramic X5R, X7R Catch Diode The diode D1 conducts current only ...
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LT3501 applicaTions inForMaTion BST LT3501 GND V – BST SW OUT BST(MAX) IN OUT (5a LOWEST > 3V OUT BST ...
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the output capacitor integrates this current, and that the capacitor on the V pin (C ) integrates the error ampli fier output current, resulting in two poles in the loop. ...
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LT3501 applicaTions inForMaTion If the synchronization signal powers high impedance state (Hi-Z), connect a resistor from the R ground. The equivalent resistance seen from the R pin to ground will set the start-up frequency. If the synchronization ...
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At power-up, a reset signal sets the soft-start latch and discharges both SS pins to approximately 0V to ensure proper start-up. When both SS pins are fully discharged the latch is reset and the internal 3.25µA current source ...
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LT3501 applicaTions inForMaTion Independent Start-Up V OUT1 0.5V/DIV PG1 V OUT2 0.5V/DIV PG2 5ms/DIV 3.3V SS1 V OUT1 0.1µF LT3501 PG1 1.8V SS2 V OUT2 0.22µF PG2 (9a) Output Sequencing PG2 10ms/DIV SS1 0.1µF LT3501 SS2 0.1µF (9d) 22 Ratiometric ...
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TO 24V PMEG4005 V OUT1 5V 47µF 42.3k 8.06k 10pF Figure 10. 5V and 1.2V 2-Stage Step-Down Converter with Output Sequencing inductor size by allowing an increase in frequency. A dual step-down application (Figure 10) steps down ...
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LT3501 applicaTions inForMaTion LT3501 GND (11a) Figure 11. Subtracting the Current When the Switch Is On (11a) from the Current When the Switch is Off (11b) Reveals the Path of the High Frequency Switching Current (11c). Keep ...
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Place additional vias near the catch diodes. Adding more copper to the top and bottom layers and tying this copper to the internal planes with vias can further reduce ther- mal resistance. With these steps, the thermal resistance ...
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LT3501 Typical applicaTions V IN 12V 4.7µF PMEG4005 V OUT1 5V 47µF 42.3k 8.06k 16.9k 7.68k 25V IN PMEG4005 V OUT1 3.3V 6A 47µF 24.9k ×2 8.06k 26 5V and 2.5V with Absolute Tracking V V IN1 ...
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Typical applicaTions V 4. 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 V OUT1 3.3V 1.25MHz Single 3.3V/6A Low Ripple Output ...
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LT3501 package DescripTion Please refer to http://www.linear.com/designtools/packaging/ 6.60 ±0.10 4.50 ±0.10 SEE NOTE 4 RECOMMENDED SOLDER PAD LAYOUT 4.30 – 4.50* (.169 – .177) 0.09 – 0.20 0.50 – 0.75 (.0035 – .0079) (.020 – .030) NOTE: 1. CONTROLLING DIMENSION: ...
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Rev D) REV DATE DESCRIPTION D 6/12 Part Marking clarification Solder pad clarification Information furnished by Linear Technology corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. ...
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