MIC26950 MICREL, MIC26950 Datasheet
MIC26950
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MIC26950 Summary of contents
Page 1
... This digitally modified adaptive t ON combines the advantages of fixed-frequency operation and fast transient response in a single device. The MIC26950 offers a full suite of protection features to ensure protection of the IC during fault conditions. These include undervoltage lockout to ensure proper operation under power-sag conditions, internal soft-start to reduce inrush current, fold-back current limit, “ ...
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... A 2.2µF ceramic capacitor from the VDD pin-to-PGND is recommended for clean operation. Power Ground. PGND is the ground path for the MIC26950 buck converter power stage. The PGND pin connects to the sources of low-side N-Channel internal MOSFETs, the negative terminals of input ...
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... VDD pin and the BST pin. A boost capacitor of 0.1μF is connected between the BST pin and the SW pin 10, Switch Node (Output): Internal connection for the high-side MOSFET source and low-side MOSFET SW 11, 12 drain. 23 VIN Power Supply Voltage (Input): Requires bypass capacitor to SGND Connect. www.DataSheet4U.com September 2010 3 MIC26950 M9999-091710-C ...
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... See “Applications Information.” ( )............................... 4.5V to 26V IN IN )........................... 0.8V to 5.5V OUT )............................................ 4. ................................................. ........................ −40°C to +125°C J (4) ® 5mm x 6mm MLF (θ ) .....................................36°C/W JA ≤ +125°C. J Min. Typ. 4.5 5 4.5 2.7 2.4 50 1.4 0.7 0.8 0.792 0.8 0.788 0.2 0.1 5 0.85 1.2 0.78 50 MIC26950 DD Max. Units 5 0.808 V 0.812 % % 0.4 µA M9999-091710-C ...
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... 26V 0V 0V Rising J of typically 360ns. OFF 5 ≤ +125°C. J Min. Typ. 300 225 87 0 360 31.5 V BST = 31.5V BST 155 10 MIC26950 Max. Units kHz 375 % % mΩ mΩ µA 60 µA 25 °C °C M9999-091710-C ...
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... V Operating Supply Current DD vs. Input Voltage INPUT VOLTAGE (V) Current Limit vs. Input Voltage INPUT VOLTAGE ( MIC26950 V = 1.2V OUT SWITCHING 1.2V OUT M9999-091710-C ...
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... TEMPERATURE (°C) Line Regulation vs. Temperature 0.5% = 12V 0. 12A 0.3% 0.2% 0.1% 0.0% 70 100 130 -50 -20 10 TEMPERATURE (° 12V 1.2V OUT 100 130 MIC26950 Rising Falling V = 12V 100 130 40 70 100 130 V =6V to 26V 1.2V OUT 100 130 M9999-091710-C ...
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... OUTPUT CURRENT (A) Die Temperature* : The temperature measurement was taken at the hottest point on the MIC26950 case mounted square inch PCB; see Thermal Measurement section. Actual results will depend upon the size of the PCB, ambient temperature and proximity to other heat emitting components. ...
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... Micrel, Inc. Functional Characteristics www.DataSheet4U.com September 2010 9 MIC26950 M9999-091710-C ...
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... Micrel, Inc. Functional Characteristics (Continued) www.DataSheet4U.com September 2010 10 MIC26950 M9999-091710-C ...
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... Micrel, Inc. Functional Characteristics (Continued) www.DataSheet4U.com September 2010 11 MIC26950 M9999-091710-C ...
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... Micrel, Inc. Functional Diagram www.DataSheet4U.com September 2010 Figure 1. MIC26950 Block Diagram 12 MIC26950 M9999-091710-C ...
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... Theory of Operation Figure 1 illustrates the block diagram for the control loop of the MIC26950. The output voltage is sensed by the MIC26950 feedback pin FB via the voltage divider R1 and R2, and compared to a 0.8V reference voltage V at ...
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... Micrel, Inc. Figure 3 shows the operation of the MIC26950 during a load transient. The output voltage drops due to the sudden load increase, which causes the V than V . This will cause the error comparator to trigger REF an ON-time period. At the end of the ON-time period, a minimum OFF-time t ...
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... DD DIODE . Diode D1. An approximate 30ns delay between the high-side and low-side driver transitions is used to prevent current from simultaneously flowing unimpeded through both MOSFETs. 15 MIC26950 is recharged through BST , which is in series with C G supply voltage where V is the voltage drop across ...
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... September 2010 Maximizing efficiency requires the proper selection of core material and minimizing the winding resistance. The high frequency operation of the MIC26950 requires the use of ferrite materials for all but the most cost sensitive applications. Lower cost iron powder cores may be used but the increase in core loss will reduce the efficiency of the power supply ...
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... If the feedback voltage ripple is so small that the g the MIC26950 will lose control and the output voltage is not regulated. In order to have some amount of V ripple, a ripple injection method is applied for low output voltage ripple applications ...
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... FB(pp × K div × − obtained as: inj 1 = × R (R1//R2) ( inj K div as 100nF, which could be considered inj MIC26950 (20) (21) is 1nF to ff τ (22) D) − 1) (23) M9999-091710-C ...
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... The clamped V reduces the line regulation INJ because it is reflected back error on the FB terminal. Therefore, the maximum output voltage of the MIC26950 should be limited to 5.5V to avoid this line regulation problem. www.DataSheet4U.com September 2010 Thermal Measurements Measuring the IC’s case temperature is recommended to ensure it is within its operating limits ...
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... PCB Layout is critical to achieve reliable, stable and efficient performance. A ground plane is required to control EMI and minimize the inductance in power, signal and return paths. The following guidelines should be followed to insure proper operation of the MIC26950 converter. IC • The 2.2µF ceramic capacitor, which is connected to the V terminal, must be located right at the IC ...
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... Micrel, Inc. Evaluation Board Schematic www.DataSheet4U.com September 2010 Figure 8. Schematic of MIC26950 Evaluation Board (J13, R13, R15 are for testing purposes) 21 MIC26950 M9999-091710-C ...
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... Central Semi 5.6V Zener Diode (9) Cooper Bussmann 2.2µH Inductor, 15A Saturation Current ZETEX 50V NPN Transistor Vishay Dale 4.75Ω Resistor, Size 0603, 1% Vishay Dale 1.21Ω Resistor, Size 0805, 1% Vishay Dale 10kΩ Resistor, Size 0603 MIC26950 Qty ...
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... Resistor, Size 0603, 1% Vishay Dale 1.91kΩ Resistor, Size 0603, 1% Vishay Dale 0Ω Resistor, Size 0603, 5% Vishay Dale 5.23kΩ Resistor, Size 0603, 1% Vishay Dale 49.9Ω Resistor, Size 0603, 1% (10) Micrel. Inc. 26V/12A Synchronous Buck DC-DC Regulator 23 MIC26950 Qty ...
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... Micrel, Inc. PCB Layout www.DataSheet4U.com Figure 10. MIC26950 Evaluation Board Mid-Layer 1 (Ground Plane) September 2010 Figure 9. MIC26950 Evaluation Board Top Layer 24 MIC26950 M9999-091710-C ...
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... Micrel, Inc. PCB Layout (Continued) www.DataSheet4U.com September 2010 Figure 11. MIC26950 Evaluation Board Mid-Layer 2 Figure 12. MIC26950 Evaluation Board Bottom Layer 25 MIC26950 M9999-091710-C ...
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... Micrel, Inc. Recommended Land Pattern www.DataSheet4U.com September 2010 26 MIC26950 M9999-091710-C ...
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... Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk and Purchaser agrees to fully September 2010 28-Pin 5mm x 6mm MLF indemnify Micrel for any damages resulting from such use or sale. © 2010 Micrel, Incorporated. 27 ® (YJL) MIC26950 M9999-091710-C ...