lm21215a-1 National Semiconductor Corporation, lm21215a-1 Datasheet
lm21215a-1
Related parts for lm21215a-1
lm21215a-1 Summary of contents
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... Fault detection and supply sequencing are possible with the inte- grated power good circuit. The LM21215A-1 is designed to work well in multi-rail power supply architectures. The output voltage of the device can be configured to track an external voltage rail using the SS/TRK pin ...
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... Top View eTSSOP-20 Package NSC Package Drawing Package Marking MYB20A LM21215AMH-1 MYB20A LM21215AMH-1 MYB20A LM21215AMH-1 Description Frequency Synchronization input pin. Applying a clock signal to this pin will force the device to switch at the clock frequency. If left unconnected, the frequency will default to 500 kHz. ...
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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. PVIN(Note 2), AVIN to GND SW(Note 3), EN, FB, COMP, −0.3V to PVIN + 0.3V PGOOD, SS/TRK to GND ...
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Symbol Parameter SYSTEM I Feedback Pin Bias Current FB I COMP Output Source Current COMPSRC I COMP Output Sink Current COMPSINK POWERGOOD V Over Voltage Protection Rising Threshold OVP V Over Voltage Protection Hysteresis OVPHYS V Under Voltage Protection Rising ...
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Typical Performance Characteristics (1.8mΩ 33nF 500 kHz, T DCR SS SW others. Efficiency 100 FSW = 500 kHz FSW = 750 kHz 98 FSW = 1 MHz ...
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Non-Switching I and I AVIN PVIN 1.20 IAVIN IPVIN 1.17 1.14 1.11 1.08 1.05 1.02 0.99 0.96 0.93 0.90 -40 - 100 120 JUNCTION TEMPERATURE (°C) Enable Threshold and Hysteresis vs. Temperature V IHENR V ...
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Minimum On-Time vs. Temperature 160 156 152 148 144 140 136 132 128 124 120 -40 - 100 120 JUNCTION TEMPERATURE (°C) Peak Current Limit vs. Temperature 19.6 19.5 19.4 19.3 19.2 19.1 19.0 18.9 ...
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Output Voltage Ripple 2 µs/DIV Startup with SS/TRK Open Circuit 200 µs/DIV Output Over-Current Condition 10 µs/DIV www.national.com Startup with Prebiased Output 30152164 Startup with applied Track Signal 30152166 30152180 8 30152163 2 ms/DIV 30152167 200 ms/DIV ...
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Block Diagram 9 30152103 www.national.com ...
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... Figure clock signal is present, the LM21215A-1 will default to a switching frequency of 500 kHz. The clock signal can be present on the SYNC pin before the device is powered on with no loading on the clock signal. Al- ternatively clock is present while the device is powered up, it will begin switching at the default frequency of 500 kHz ...
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... FIGURE 2. Current Limit Conditions POWERGOOD FLAG The PGOOD pin provides the user with a way to monitor the status of the LM21215A-1. In order to use the PGOOD pin, the application must provide a pull-up resistor to a desired DC voltage (i.e. Vin). PGOOD will respond to a fault condition by pulling the PGOOD pin low with the open-drain output. ...
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... LIGHT LOAD OPERATION The LM21215A-1 offers increased efficiency when operating at light loads. Whenever the load current is reduced to a point where the peak to peak inductor ripple current is greater than two times the load current, the device will enter the diode em- ulation mode preventing significant negative inductor current. ...
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... FIGURE 4. Modes of Operation for LM21215A-1 13 30152179 www.national.com ...
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... FB1 PRECISION ENABLE The enable (EN) pin of the LM21215A-1 allows the output to be toggled on and off. This pin is a precision analog input. When the voltage exceeds 1.35V, the controller will try to reg- ulate the output voltage as long as the input voltage has exceeded the UVLO voltage of 2 ...
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... This will depend on the impedance between the input voltage supply and the LM21215A-1, as well as the magnitude and slew rate of the output transient. The AVIN pin requires a 1 µF ceramic capacitor to AGND and a 1Ω ...
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There are three main blocks of a voltage mode buck switcher that the power supply designer must consider when designing the control system; the power train, modulator, and the com- pensated error amplifier. A closed loop diagram is shown in ...
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GAIN PHASE -20 100 1k 10k 100k FREQUENCY (Hz) FIGURE 11. Type 3 Compensation Network Bode Plot As seen in Figure 11, the two zeros (f LC sation network give a phase boost. This ...
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... CROSSOVER may help but usually at the expense of phase margin. THERMAL CONSIDERATIONS The thermal characteristics of the LM21215A-1 are specified using the parameter θ , which relates the junction tempera- JA ture to the ambient temperature. Although the value of θ dependant on many variables, it still can be used to approxi- mate the operating junction temperature of the device ...
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... The inductor can be placed on the bottom side of the PCB relative to the LM21215A-1, but care must be taken to not allow any coupling of the magnetic field of the inductor into the sensitive feedback or compensation traces. ...
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Bill of Materials (V = 3.3V - 5.5V DESCRIPTION C CAP, CERM, 1 uF, 10V, +/-10%, F X7R, 0603 CAP, CERM, 100 uF, 6.3V, IN1 IN2 IN3 +/-20%, X5R, 1206 C ...
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Bill of Materials (V = 4.0V - 5.5V DESCRIPTION C CAP, CERM, 1 uF, 10V, +/-10%, F X7R, 0603 CAP, CERM, 100 uF, 6.3V, IN1 O1 O2 +/-20%, X5R, 1206 C CAP, ...
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Physical Dimensions www.national.com inches (millimeters) unless otherwise noted 20-Lead eTSSOP Package NS Package Number MYB20 22 ...
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Notes 23 www.national.com ...
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... National Semiconductor and the National Semiconductor logo are registered trademarks of National Semiconductor Corporation. All other brand or product names may be trademarks or registered trademarks of their respective holders. ...