LT1959CS8#PBF Linear Technology, LT1959CS8#PBF Datasheet
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LT1959CS8#PBF
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LT1959CS8#PBF Summary of contents
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... There is the optional function of shutdown or synchronization. A shutdown signal reduces supply current Synchronization allows an external logic level sig- nal to increase the internal oscillator from 580kHz to 1MHz. , LTC and LT are registered trademarks of Linear Technology Corporation OUTPUT 1 ...
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LT1959 ABSOLUTE MAXIMUM Input Voltage .......................................................... 16V BOOST Voltage ........................................................ 30V BOOST Pin Above Input Voltage ............................. 15V SHDN Pin Voltage ..................................................... 7V FB Pin Voltage ....................................................... 3.5V FB Pin Current ....................................................... 1mA U PACKAGE/ORDER INFORMATION FRONT ...
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ELECTRICAL CHARACTERISTICS temperature range, otherwise specifications are at T otherwise noted. PARAMETER Switch On Resistance (Note 7) Maximum Switch Duty Cycle Switch Frequency Switch Frequency Line Regulation Frequency Shifting Threshold on FB Pin Minimum Input Voltage (Note 3) Minimum Boost ...
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LT1959 W U TYPICAL PERFORMANCE CHARACTERISTICS Minimum Input Voltage with 3.3V Output 4.7 4.5 4.3 4.1 3.9 3.7 3.5 3 100 1000 LOAD CURRENT (mA) 1959 G01 Shutdown Pin Bias Current –500 AT 0.37V SHUTDOWN THRESHOLD. AFTER SHUTDOWN, ...
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W U TYPICAL PERFORMANCE CHARACTERISTICS Frequency Foldback 500 SWITCHING FREQUENCY 400 300 200 100 FEEDBACK PIN CURRENT 0 0 0.2 0.4 0.6 0.8 1.0 1.2 FEEDBACK PIN VOLTAGE (V) 1959 • G10 Maximum Load Current 3.3V OUT ...
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LT1959 PIN FUNCTIONS FB: The feedback pin is used to set output voltage using an external voltage divider that generates 1.21V at the pin with the desired output voltage. Three additional functions are performed by the FB ...
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W BLOCK DIAGRAM The LT1959 is a constant frequency, current mode buck converter. This means that there is an internal clock and two feedback loops that control the duty cycle of the power switch. In addition to the normal error ...
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LT1959 U U APPLICATIONS INFORMATION FEEDBACK PIN FUNCTIONS The feedback (FB) pin on the LT1959 is used to set output voltage and provide several overload protection features. The first part of this section deals with selecting resistors to set output ...
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U U APPLICATIONS INFORMATION The internal circuitry which forces reduced switching frequency also causes current to flow out of the feedback pin when output voltage is low. The equivalent circuitry is shown in Figure completely off during ...
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... After making an initial choice, consider the secondary things like output voltage ripple, second sourcing, etc. Use the experts in the Linear Technology’s applica- tions department if you feel uncertain about the final choice. They have experience with a wide range of inductor types and can tell you about the latest devel- opments in low profile, surface mounting, etc ...
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U U APPLICATIONS INFORMATION Table 2 SERIES VENDOR/ VALUE DC CORE RESIS- PART NO (Amps) TYPE TANCE( ) Coiltronics CTX2-1 2 4.1 Tor 0.011 CTX5-4 5 4.4 Tor 0.019 CTX8-4 8 3.5 Tor 0.020 CTX2-1P 2 3.4 Tor ...
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LT1959 U U APPLICATIONS INFORMATION Ceramic Capacitors Higher value, lower cost ceramic capacitors are now available in smaller case sizes. These are ideal for input bypassing because of their high ripple rating and tolerance to turn-on surges. As output capacitors, ...
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U U APPLICATIONS INFORMATION and does not fall to less than 1/3 of nominal output voltage, foldback will not take effect. With the overloaded condi- tion, output current will increase to a typical value of 5.7A, determined by peak switch ...
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LT1959 U U APPLICATIONS INFORMATION INPUT Keep the connections from the resistors to the shutdown pin short and make sure that interplane or surface capaci- tance to the switching nodes are minimized. If high resistor ...
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U U APPLICATIONS INFORMATION from the switch node. Also note that the high current ground path of the catch diode and input capacitor are kept very short and separate from the analog ground line. The high speed switching current path ...
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LT1959 U U APPLICATIONS INFORMATION PARASITIC RESONANCE Resonance or “ringing” may sometimes be seen on the switch node (see Figure 7). Very high frequency ringing following switch rise time is caused by switch/diode/input capacitor lead inductance and diode capacitance. Schot- ...
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U U APPLICATIONS INFORMATION The term inside the radical has a maximum value of 0.5 when input voltage is twice output, and stays near 0.5 for a relatively wide range of input voltages common practice therefore to simply ...
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LT1959 U U APPLICATIONS INFORMATION formulas show how to calculate each of these losses. These formulas assume continuous mode operation, so they should not be used for calculating efficiency at light load currents. Switch loss ...
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U U APPLICATIONS INFORMATION 40 GAIN 20 0 PHASE –20 –40 10 100 1k 10k FREQUENCY (Hz) Figure 10. Response from V C Error amplifier transconductance phase and gain are shown in Figure 11. The error amplifier can be modeled ...
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LT1959 U U APPLICATIONS INFORMATION G = Transconductance of power stage = 5.3A Error amplifier transconductance = 2(10 MA ESR = Output capacitor ESR 1.21 = Reference voltage With and ESR = 0.03 , ...
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U U APPLICATIONS INFORMATION ADJUSTABLE INPUT SUPPLY 10mV/DIV 5A/DIV 0.2ms/DIV Figure 14. Loop Stability Check The output of the regulator contains both the desired low frequency transient information and a reasonable amount of high frequency (500kHz) ripple. The ripple makes ...
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LT1959 U U APPLICATIONS INFORMATION converters 120 out of phase with each other reduces input and output ripple currents. This reduces the ripple rating, size and cost of filter capacitors. Current Sharing/Split Input Supplies Current sharing is accomplished by joining ...
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... Figure 16. Buck Converter with Adjustable Soft Start 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 represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights. ...
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... Synchronous Step-Down Switching Regulator Controller High Efficiency, Low Ripple LTC1735 High Efficiency Step-Down Converter LT1775 High Power NoR SENSE trademark of Linear Technology Corporation SENSE Linear Technology Corporation 24 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 www.linear-tech.com U Dimensions in inches (millimeters) unless otherwise noted. ...