lm2648mtd National Semiconductor Corporation, lm2648mtd Datasheet
lm2648mtd
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lm2648mtd Summary of contents
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... The FAULT_DELAY pin allows delayed shut off time for the IC during an under-voltage or PROT-IN2 fault. The LM2648 also features an adjustable UVLO feature. Block Diagram © 2004 National Semiconductor Corporation Features n Four synchronous buck regulators n Channel 3: Two-phase, current mode controller n 4.5V to 18V input range n Built in sequential startup n Channels 1 and 2: Independent, 180˚ ...
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... NC (Pin 4): All NC pins should be connected to SGND. www.national.com TOP VIEW 20059602 56-Lead TSSOP (MTD) Order Number LM2648MTD See NS Package Number MTD56 COMP1 (Pin 5): Compensation pin for Channel 1. This is the output of the internal error amplifier. The compensation net- work should be connected between this pin and the feed- back pin, FB1 (PIN 6) ...
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Pin Descriptions (Continued) Thresholds are 1.2V and 1.9V typical for shutdown and UVLO respectively. Connect to Vin through a voltage divider to set the external UVLO threshold. VLIN5 (Pin 13): The output of the internal 5V LDO regulator derived from ...
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Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Voltages from the indicated pins to SGND/PGND: VIN, ILIMx, KS3a, KS3b SWx, RSNSx FB1, FB2, FB3x, VDDx,ON/UVLO COMPx, FAULT_DELAY, ...
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Electrical Characteristics Unless otherwise specified 12V, SGND = PGND = 0V, VLIN5 = VDD1 = VDD2 = VDD3x. Limits appearing in boldface IN type apply over the full operating junction temperature range. Specifications appearing in plain type are ...
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Electrical Characteristics Unless otherwise specified 12V, SGND = PGND = 0V, VLIN5 = VDD1 = VDD2 = VDD3x. Limits appearing in boldface IN type apply over the full operating junction temperature range. Specifications appearing in plain type are ...
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... Note 3: For detailed information on soldering plastic small-outline packages, refer to the Packaging Databook available from National Semiconductor Corporation. Note 4: For testing purposes, ESD was applied using the human-body model, a 100pF capacitor discharged through a 1.5kΩ resistor. ...
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Typical Performance Characteristics Efficiency vs Load Current Ch.1 = 5V, Ch.2 = 3.3V 12V, Ch.1/2/ Voltage vs Temperature Input Supply Current vs V Shutdown Mode IN Efficiency vs Load Current Ch.3 = 1.9V, V 20059664 ...
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Typical Performance Characteristics TD1 2-3 Source Current vs Temperature VIN - VLIN5 Saturation Voltage vs Temperature Ch.2 Load Transient Response 3.3V , 12V (20µsec/div) OUT IN www.national.com (Continued) TD1 2-3 Threshold Voltage vs Temperature 20059670 Ch.1 Load Transient Response 5V ...
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Typical Performance Characteristics Prot-in1 Shutdown (10ms/div) Softstart 1 and 2 (1ms/div) Ch.3 Softstart (10ms/div) (Continued) Prot-in2 Startup (40ms/div) 20059683 Ch.3 Sequential Startup (20ms/div) 20059685 Overcurrent UVP Shutdown (100ms/div) 20059687 13 20059684 20059686 20059688 www.national.com ...
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Typical Performance Characteristics Operating Frequency vs Temperature www.national.com (Continued) Ch.3 Error Amplifier Gain vs Temperature 20059678 14 20059679 ...
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Operation Descriptions ON and UVLO The ON/UVLO pin provides a dual threshold shutdown and under voltage lock out function. When this pin is pulled above 1.2V, the internal bias circuitry starts up and the device enters standby mode. The ON/UVLO ...
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Operation Descriptions ACTIVE OUTPUT DISCHARGE Each channel has an embedded MOSFET with the drain connected to the SWx pin to provide a smooth controlled shutdown ramp. Each MOSFET will discharge the output capacitor of its channel if the device enters ...
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Operation Descriptions Channel 3 Dual Phase Operation Channel 3 consists of two 180˚ out of phase converters operating in parallel to provide a single output voltage. In high current demand applications, current sharing between the two switching channels greatly reduces ...
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Component Selection ture as well as the maximum input voltage. Input RMS ripple current can be approximately calculated with the equation below: Where D1 is the duty cycle of channel 1 or 3a, whichever is larger, and D2 is the ...
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Component Selection transient requirements should be considered induc- tance value larger than Lmin is selected, make sure that the Cmin requirement is not violated. Since inductor ripple current is often the criterion for select- ing an output inductor, ...
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Component Selection FIGURE 6. Output-Control Transfer Function The control-output corner frequencies, and thus the desired compensation corner frequencies, can be determined ap- proximately by the following equations: Since fp is determined by the output network, it will shift with loading ...
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Component Selection FIGURE 7. Ch.3 Compensation Network Channel 1 and 2 Because the loop characteristics for channels 1 and 2 do not change with loading, the compensation network is somewhat more straightforward than for channel 3. As shown in Figure ...
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Component Selection Zero1: >> Zero2: ( fb2 c2 www.national.com PROCEDURE (Continued) The following procedure will create a 20dB/decade loop gain roll-off. First set fz2 approximately one half decade above fdp. Since this zero is set using one ...
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... Deutsch Tel: +49 (0) 69 9508 6208 English www.national.com Français Tel: +33 ( 8790 56-Lead TSSOP Package Order Number LM2648MTD NS Package Number MTD56 2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system affect its safety or effectiveness ...