MIC28304 Evaluation Board 70V 3A Power Module Hyper Speed Control™ Family General Description Getting Started The Micrel MIC28304 is synchronous step-down regulator module, featuring a unique adaptive ON-time control architecture. The module incorporates a DC-to-DC controller, power MOSFETs, bootstrap diode, bootstrap capacitor, and an inductor in a single package. The MIC28304 operates over an input supply range of 4.5V to 70V and can be used to supply up to 3A of output current. The output voltage is adjustable down to 0.8V with a guaranteed accuracy of ±1%. The device operates with a programmable switching frequency from 200kHz to 600kHz. 1. VIN Supply Connect a supply to the VIN and GND terminals, paying careful attention to the polarity and the supply range (7V < VIN < 70V). Monitor IIN with a current meter and monitor input voltage at VIN and GND terminals with a voltmeter. Do not apply power until step 4. ® The MIC28304-1 has the HyperLight Load architecture, so it can operate in pulse skipping mode at light load. However, it operates in fixed frequency CCM mode from medium load to heavy load. The MIC28304-2 has Hyper Speed Control™ architecture, which operates in fixed frequency CCM mode under all load conditions. The basic parameters of the evaluation board are: • Input: 7V to 70V • Output: 0.8V to 5V at 3A(1) • 600kHz Switching Frequency (Adjustable 200kHz to 600kHz) 2. Connect Load and Monitor Output Connect a load to the VOUT and GND terminals. The load can be either a passive (resistive) or an active (as in an electronic load) type. A current meter may be placed between the VOUT terminal and load to monitor the output current. Ensure the output voltage is monitored at the VOUT terminal. 3. Enable Input The EN pin has an on board 100kΩ pull-up resistor (R16) to VIN, which allows the output to be turned on when PVDD exceeds its UVLO threshold. An EN connector is provided on the evaluation board for users to easily access the enable feature. Applying an external logic signal on the EN pin to pull it low or using a jumper to short the EN pin to GND will shut off the output of the MIC28304 evaluation board. Note: 1. Refer to temperature curves shown in the MIC28304 0.8V to 5V/3A Evaluation Board Typical Characteristics section. Datasheets and support documentation are available on Micrel’s web site at: www.micrel.com. Requirements The MIC28304-1 and MIC28304-2 evaluation board requires only a single power supply with at least 10A current capability. No external linear regulator is required to power the internal biasing of the IC because the MIC28304 has internal PVDD LDO. In the applications with VIN < +5.5V, PVDD should be tied to VIN to bypass the internal linear regulator. The output load can either be a passive or an active load. Precautions The MIC28304 evaluation board does not have reverse polarity protection. Applying a negative voltage to the VIN and GND terminals may damage the device. The maximum VIN of the board is rated at 70V. Exceeding 70V on the VIN could damage the device. 4. Turn Power Turn on the VIN supply and verify that the output voltage is regulated to 5V. Ordering Information Part Number Description MIC28304-1 5V EV MIC28304-1 Evaluation Board up to 5V Output MIC28304-2 5V EV MIC28304-2 Evaluation Board up to 5V Output MIC28304-1 12V EV MIC28304-1 Evaluation Board 12V Output MIC28304-2 12V EV MIC28304-2 Evaluation Board 12V Output Hyper LightLoad is a registered trademark and Hyper Speed Control is a trademark of Micrel, Inc. Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com April 29, 2014 Revision 1.0 Micrel, Inc. MIC28304 Evaluation Board gives a 0.8V output voltage. All other voltages not listed above can be set by modifying RBOTTOM value according to: Features Feedback Resistors The output voltage on the MIC28304 evaluation board, which is preset to 5.0V, is determined by the feedback divider: VOUT R1 = VREF × 1 + RBOTTOM RBOTTOM = R1× VREF VOUT − VREF Eq. 2 Note that the output voltage should not be set to exceed 5V due to the 6.3V voltage rating on the output capacitors. For higher output voltage, use the Ordering Information table. Table 1 gives the typical values of some of the components, for details refer to Bill of Material table. Eq. 1 where VREF = 0.8V, and RBOTTOM is one of R10, or R11, which corresponds to 3.3V, 5V. Leaving the RBOTTOM open Table 1. Typical Values of Some Components VOUT VIN R3 (Rinj) R1 (Top Feedback Resistor) R11 (Bottom Feedback Resistor) C10 (Cinj) C12 (Cff) 0.9V 5V to 70V 16.5kΩ 10kΩ 80.6kΩ 0.1µF 2.2nF 47µF /6.3V or 2 x 22µF 1.2V 5V to 70V 16.5kΩ 10kΩ 20kΩ 0.1µF 2.2nF 47µF /6.3V or 2 x 22µF 1.8V 5V to 70V 16.5kΩ 10kΩ 8.06kΩ 0.1µF 2.2nF 47µF /6.3V or 2 x 22µF 2.5V 5V to 70V 16.5kΩ 10kΩ 4.75kΩ 0.1µF 2.2nF 47µF /6.3V or 2 x 22µF 3.3V 5V to 70V 16.5kΩ 10kΩ 3.24kΩ 0.1µF 2.2nF 47µF /6.3V or 2 x 22µF 5V 7V to 70V 16.5kΩ 10kΩ 1.9kΩ 0.1µF 2.2nF 47µF/6.3V or 2 x 22µF 12V 18V to 70V 23.2kΩ 10kΩ 715Ω 0.1µF 2.2nF 47µF/16V or 2 x 22µF April 29, 2014 2 COUT Revision 1.0 Micrel, Inc. MIC28304 Evaluation Board The short circuit current limit can be programmed by using the following formula: SW Node Test point J1 (VSW) is placed for monitoring the switching waveform, which is one of the most critical waveforms for the converter. R15 = Current Limit The MIC28304 uses the RDS(ON) of the low-side MOSFET and external resistor connected from the ILIM pin to the SW node to decide the current limit. RDS(ON) = On-resistance of low-side power MOSFET, 57mΩ typically VCL = Current-limit threshold (typical absolute value is 14mV per Electrical Characteristics Table in MIC28304 data sheet) BST ICL = Current-limit source current (typical value is 80µA, per the Electrical Characteristics table). SW CS ΔIL(PP) = Inductor current peak-to-peak, since the inductor is integrated use Equation 4 to calculate the inductor ripple current. VIN 2.2µF x2 SW R15 The peak-to-peak inductor current ripple is: ILIM C6 ∆IL(PP) = FB PGND VOUT × (VIN(max) − VOUT ) Eq. 4 VIN(max) × fsw × L The MIC28304 has 4.7µH inductor integrated into the module. The typical value of RWINDING(DCR) of this particular inductor is in the range of 45mΩ. Figure 1. MIC28304 Current Limiting Circuit In case of hard short, the short limit is folded down to allow an indefinite hard short on the output without any destructive effect. It is mandatory to make sure that the inductor current used to charge the output capacitance during soft start is under the folded short limit; otherwise the supply will go in hiccup mode and may not be finishing the soft start successfully. In each switching cycle of the MIC28304, the inductor current is sensed by monitoring the low-side MOSFET in the OFF period. The sensed voltage V(ILIM) is compared with the power ground (PGND) after a blanking time of 150ns. In this way the drop voltage over the resistor R15 (VCL) is compared with the drop over the bottom FET generating the short current limit. The small capacitor (C6) connected from ILIM pin to PGND filters the switching node ringing during the off-time allowing a better short limit measurement. The time constant created by R15 and C6 should be much less than the minimum off time. The MOSFET RDS(ON) varies 30 to 40% with temperature. Therefore, it is recommended to add a 50% margin to ICLIM in the above equation to avoid false current limiting due to increased MOSFET junction temperature rise. The following table shows typical output current limit value for a given R15 with C6 = 10pF. The VCL drop allows programming of short limit through the value of the resistor (R15), If the absolute value of the voltage drop on the bottom FET is greater than VCL. In that case the V(ILIM) is lower than PGND and a short circuit event is triggered. A hiccup cycle to treat the short event is generated. The hiccup sequence including the soft start reduces the stress on the switching FETs and protects the load and supply for severe short conditions. April 29, 2014 Eq. 3 ICL ICLIM = Desired current limit MIC28304 VIN (ICLIM − ∆IL (PP ) × 0.5) × R DS(ON) + VCL 3 R15 Typical Output Current Limit 1.81kΩ 3A 2.7kΩ 6.3A Revision 1.0 Micrel, Inc. MIC28304 Evaluation Board Loop Gain Measurement Resistor R14 is placed in series with the regulator feedback path. The control loop gain can be measured by connecting an impedance analyzer across the resistor and selecting the resistor value in between 20Ω to 50Ω. The following formula gives the estimated switching frequency: Setting the Switching Frequency The MIC28304 switching frequency can be adjusted by changing the value of resistor R19. The top resistor of 100kΩ is internal to module and is connected between VIN and FREQ pin, so the value of R19 sets the switching frequency. The switching frequency also depends on VIN, VOUT and load conditions. Where fO = Switching Frequency when R19 is open. For a more precise setting, it is recommended to use the following graph: fSW _ ADJ = fO × R19 R19 + 100kΩ Eq. 5 Switching Frequency 800 700 VIN = 12V SW FREQ (kHz) 600 MIC28304 BST 500 VIN = 48V 400 300 200 VIN VIN 100 RFREQ 2.2µF x2 FREQ 100kΩ SW CS 0 10.00 VOUT = 5V IOUT = 2A 100.00 1000.00 10000.00 R19 (kΩ) R19 FB Figure 3. Switching Frequency vs. R19 PGND Figure 2. Switching Frequency Adjustment April 29, 2014 4 Revision 1.0 Micrel, Inc. MIC28304 Evaluation Board MIC28304 0.8V to 5V/3A Evaluation Board Typical Characteristics Efficiency (VIN = 12V) vs. Output Current (MIC28304-1) Efficiency (VIN = 18V) vs. Output Current (MIC28304-1) 100 90 90 5.0V 3.3V 2.5V 1.8V 1.2V 0.8V 70 60 90 5.0V 3.3V 2.5V 1.8V 1.2V 0.8V 80 EFFICIENCY (%) 50 40 70 60 50 40 30 30 FSW = 600kHz CCM 10 0.01 0.1 1 10 0.01 0.1 OUTPUT CURRENT (A) Efficiency (VIN =12V) vs. Output Current (MIC28304-2) 90 60 50 Efficiency (VIN = 24V) vs. Output Current (MIC28304-2) 100 FSW = 600kHz 90 5.0V 3.3V 2.5V 1.8V 1.2V 0.8V 80 50 1 1.5 2 2.5 3 3.5 60 50 40 0 4 0.5 1 1.5 2 2.5 3 3.5 30 4 0 Thermal Derating Thermal Derating VOUT = 3.3V FSW = 600kHz MIC28304-2 Tj_MAX = 125°C VIN = 24V 1 LOAD CURRENT (A) VIN = 48V 2 VIN = 18V 55 70 85 MAXIMUM AMBIENT TEMPERATURE (°C) 100 3 3.5 4 VIN = 48V VIN = 24V 1 VIN = 12V 2 VIN =18V VIN = 48V VIN = 24V 1 VIN = 70V VIN = 70V 40 2.5 VOUT = 2.5V FSW = 600kHz MIC28304-2 Tj_MAX = 125°C VIN = 12V 0 0 25 2 Thermal Derating VIN = 70V 0 1.5 3 VIN = 12V VIN = 18V 1 OUTPUT CURRENT (A) 3 3 2 0.5 OUTPUT CURRENT (A) OUTPUT CURRENT (A) VOUT = 5V FSW = 600kHz MIC28304-2 Tj_MAX = 125°C 5.0V 3.3V 2.5V 1.8V 1.2V 0.8V 70 30 0.5 10 Efficiency (VIN = 18V) vs. Output Current (MIC28304-2) 40 0 1 OUTPUT CURRENT (A) 60 30 0.1 OUTPUT CURRENT (A) 70 40 FSW = 600kHz CCM 10 0.01 10 80 EFFICIENCY (%) EFFICIENCY (%) 70 0.8V 40 90 5.0V 3.3V 2.5V 1.8V 1.2V 0.8V 80 1 FSW = 600kHz FSW = 600kHz 1.2V 50 20 100 100 60 30 FSW = 600kHz CCM 20 10 5.0V 3.3V 2.5V 1.8V 70 EFFICIENCY (%) 20 LOAD CURRENT (A) 80 LOAD CURRENT (A) EFFICIENCY (%) 80 100 EFFICIENCY (%) 100 Efficiency (VIN = 24V) vs. Output Current (MIC28304-1) 25 40 55 70 85 MAXIMUM AMBIENT TEMPERATURE (°C) 100 25 40 55 70 85 100 MAXIMUM AMBIENT TEMPERATURE (°C) Die Temperature* : The temperature measurement was taken at the hottest point on the MIC28304 case mounted on a 5 square inch 4 layer, 0.62”, FR-4 PCB with 2oz. finish copper weight per layer. Actual results will depend upon the size of the PCB, ambient temperature and proximity to other heat emitting components. April 29, 2014 5 Revision 1.0 Micrel, Inc. MIC28304 Evaluation Board MIC28304 0.8V to 5V/3A Output Evaluation Board Schematic Figure 4. Schematic of MIC28304 Evaluation Board (J1, J8, J10, J11, J12, J13, R14, R20, and R21 are for testing purposes) April 29, 2014 6 Revision 1.0 Micrel, Inc. MIC28304 Evaluation Board MIC28304 0.8V to 5V/3A Output Evaluation Board Schematic (Continued) Figure 5. Schematic of MIC28304 Evaluation Board (Optimized for Smallest Footprint) April 29, 2014 7 Revision 1.0 Micrel, Inc. MIC28304 Evaluation Board Bill of Materials 0.8V to 5V/3A Output Item C1, C1A Part Number (2) EEU-FC2A101 GRM32ER72A225K C2, C3, C2A(2), (2) C3A C6, C6A(2) 12101C225KAT2A AVX GCM1885C2A100JA16D Murata C10, C17, C10A(2), (2) C17A C1608X5R0J105K TDK C1608X7S2A104K GRM188R72A102KA01D C11, C11A C12, C12A C14, C14A(2) C16, C16A AVX Murata TDK 4 10pF, 100V, 0603, NPO 2 1µF/6.3V Ceramic Capacitor, X7R, Size 0603 2 0.47µF/100V Ceramic Capacitor, X7R, Size 0805 2 4 0.1µF/100V, X7S, 0603 1nF/100V Ceramic Capacitor, X7R, Size 0603 2 2.2nF/100V Ceramic Capacitor, X7R, Size 0603 2 47µF/6.3V Ceramic Capacitor, X5R, Size 1210 2 0.1µF/6.3V Ceramic Capacitor, X7R, Size 0603 2 Murata 06031C222KAT2A AVX C1608X7R2A222K TDK 12106D476MAT2A 2.2µF/100V Ceramic Capacitor, X7R, Size 1210 Murata C1608X7R2A102K GRM31CR60J476ME19K 2 0.1µF/100V Ceramic Capacitor, X7R, Size 0603 TDK AVX GRM188R71H104KA93D (2) Murata 06031C102KAT2A GRM188R72A222KA01D (2) 100µF Aluminum Capacitor, 100V Murata AVX GRM188R72A104KA35D (2) AVX 06036C105KAT2A 08051C474KAT2A Qty Murata (6) GRM21BR72A474KA73 C9, C9A(2) Description (3) (4) TDK(5) GRM188R70J105KA01D C8, C8A Panasonic C3225X7R2A225K 06031A100JAT2A (2) Manufacturer Murata AVX Murata 06035C104KAT2A AVX C1608X7R1H104K TDK C4, C5, C7, C13, C15, C4A(2), C7A(2), (2) C15A DNP Notes: 2. Either reference designator, that is, a reference designator ending with “A” or ending without “A,” can be used as part of customer design. 3. Panasonic: www.panasonic.com. 4. Murata: www.murata.com. 5. TDK: www.tdk.com. 6. AVX: www.avx.com. April 29, 2014 8 Revision 1.0 Micrel, Inc. MIC28304 Evaluation Board Bill of Materials 0.8V to 5V/3A Output (Continued) Item Part Number Manufacturer Description R1, R1A(2) CRCW060310K0FKEA Vishay Dale(7) 10kΩ Resistor, Size 0603, 1% 2 R2, R2A(2) CRCW08051R21FKEA Vishay Dale 1.21Ω Resistor, Size 0805, 5% 2 CRCW06031652F Vishay Dale 16.5kΩ Resistor, Size 0603, 1% 2 CRCW06033K24FKEA Vishay Dale 3.24kΩ Resistor, Size 0603, 1% 1 CRCW06031K91FKEA Vishay Dale 1.91kΩ Resistor, Size 0603, 1% 2 CRCW0603715R0FKEA Vishay Dale 715Ω Resistor, Size 0603, 1% R3, R3A (2) R10, R11, R11A (2) R12 (2) R14, R20, R20A Qty DNP CRCW06030000FKEA Vishay Dale 0Ω Resistor, Size 0603, 5% 3 R15, R15A (2) CRCW04022K70JNED Vishay Dale 2.7kΩ Resistor, Size 0603, 1% 2 R16, R16A (2) CRCW0603100KFKEAHP Vishay Dale 100kΩ Resistor, Size 0603, 1% 2 R18, R18A (2) CRCW060349K9FKEA Vishay Dale 49.9kΩ Resistor, Size 0603, 1% 2 CRCW060349R9FKEA Vishay Dale 49.9Ω Resistor, Size 0603, 1% 1 CRCW06031R21FKEA Vishay Dale 1.21Ω Resistor, Size 0603, 1% 2 R21 R23, R23A (2) R4, R19, R19A (2) U1, U1A(2) DNP MIC28304-1YMP MIC28304-2YMP Micrel. Inc.(8) 70V, 3A Power Module 2 Notes: 7. Vishay: www.vishay.com. 8. Micrel, Inc.: www.micrel.com. April 29, 2014 9 Revision 1.0 Micrel, Inc. MIC28304 Evaluation Board MIC28304 0.8V to 12V/3A Evaluation Board Typical Characteristics Efficiency vs. Output Current (MIC28304-1) Efficiency vs. Output Current (MIC28304-2) 100 18VIN 4 100 95 VOUT = 12V FSW=600kHz MIC28304-2 R3=23.2k Tj_MAX =125°C 85 80 75 70 65 VOUT = 12V FSW = 600kHz CCM R3 = 23.2k 60 55 18VIN 24VIN 36VIN 48VIN 70VIN 90 EFFICIENCY (%) 24VIN 36VIN 48VIN 85 80 75 70 VOUT = 12V FSW = 600kHz R3=23.2kΩ 65 60 0.1 1 3 18VIN 24VIN 2 48VIN 1 70VIN 55 50 50 0.01 LOAD CURRENT (A) 95 90 EFFICIENCY (%) Thermal Derating 10 0 0.6 1.2 1.8 2.4 3 OUTPUT CURRENT (A) OUTPUT CURRENT (A) 3.6 0 25 40 55 70 85 100 MAX. AMBIENT TEMPERATURE (°C) IC Power Dissipation vs. Output Current (MIC28304-2) 9 VOUT = 12V R3 = 23.2kΩ FSW = 600kHz IC POWER DISSIPATION (W) 8 7 70VIN 48VIN 36VIN 24VIN 18VIN 6 5 4 3 2 1 0 0 1 2 3 4 OUTPUT CURRENT (A) Die Temperature* : The temperature measurement was taken at the hottest point on the MIC28304 case mounted on a 5 square inch 4 layer, 0.62”, FR-4 PCB with 2oz. finish copper weight per layer. Actual results will depend upon the size of the PCB, ambient temperature and proximity to other heat emitting components. April 29, 2014 10 Revision 1.0 Micrel, Inc. MIC28304 Evaluation Board MIC28304 12V/3A Output Evaluation Board Schematic Figure 6. Schematic of MIC28304 Evaluation Board (J1, J8, J10, J11, J12, J13, R14, R20 and R21 are for testing purposes) April 29, 2014 11 Revision 1.0 Micrel, Inc. MIC28304 Evaluation Board MIC28304 12V/3A Output Evaluation Board Schematic (Continued) Figure 7. Schematic of MIC28304 Evaluation Board (Optimized for smallest footprint) April 29, 2014 12 Revision 1.0 Micrel, Inc. MIC28304 Evaluation Board Bill of Materials 12V/3A Output Item C1, C1A Part Number (9) EEU-FC2A101 GRM32ER72A225K C2, C3, (9) (9) C2A , C3A C6, C6A(9) 12101C225KAT2A AVX GCM1885C2A100JA16D Murata C10, C17, C10A(9), (9) C17A C1608X5R0J105K TDK C1608X7S2A104K GRM188R72A102KA01D C11, C11A C12, C12A C14, C14A(9) C16, C16A AVX Murata 4 10pF, 100V, 0603, NPO 2 1µF/6.3V Ceramic Capacitor, X7R, Size 0603 2 0.47µF/100V Ceramic Capacitor, X7R, Size 0805 2 0.1µF/100V,X7S,0603 Murata TDK 1nF/100V Ceramic Capacitor, X7R, Size 0603 2 2.2nF/100V Ceramic Capacitor, X7R, Size 0603 2 Murata 06031C222KAT2A AVX C1608X7R2A222K TDK EMK325BJ476MM-T 2.2µF/100V Ceramic Capacitor, X7R, Size 1210 4 C1608X7R2A102K GRM32ER61C476ME15 2 0.1µF/100V Ceramic Capacitor, X7R, Size 0603 TDK AVX GRM188R71H104KA93D (9) Murata 06031C102KAT2A GRM188R72A222KA01D (9) 100µF Aluminum Capacitor, 100V Murata AVX GRM188R72A104KA35D (9) AVX 06036C105KAT2A 08051C474KAT2A Qty Murata (13) GRM21BR72A474KA73 C9, C9A(9) Description (10) (11) TDK(12) GRM188R70J105KA01D C8, C8A Panasonic C3225X7R2A225K 06031A100JAT2A (9) Manufacturer Murata 47µF Ceramic Capacitor, X5R, Size 1210, 16V (14) Taiyo Yuden Murata 06035C104KAT2A AVX C1608X7R1H104K TDK 2 0.1µF/6.3V Ceramic Capacitor, X7R, Size 0603 2 C4, C5, C7, C13, C15, C4A(9), C7A(9), (9) C15A DNP Notes: 9. Either reference designator, that is, a reference designator ending with “A” or ending without “A,” can be used as part of customer design. 10. Panasonic: www.panasonic.com. 11. Murata: www.murata.com. 12. TDK: www.tdk.com. 13. AVX: www.avx.com. 14. Taiyo Yuden: www.taiyo-yuden.com. April 29, 2014 13 Revision 1.0 Micrel, Inc. MIC28304 Evaluation Board Bill of Materials 12V/3A Output (Continued) Item Part Number R1, R1A (9) CRCW060310K0FKEA R2, R2A (9) CRCW08051R21FKEA R3, R3A (9) R12, R11A (9) (9) R14, R20, R20A Manufacturer Vishay Dale (15) Description Qty 10kΩ Resistor, Size 0603, 1% 2 Vishay Dale 1.21Ω Resistor, Size 0805, 5% 2 CRCW060323K2FKEA Vishay Dale 23.2kΩ Resistor, Size 0603, 1% 2 CRCW0603715R0FKEA Vishay Dale 715Ω Resistor, Size 0603, 1% 2 CRCW06030000FKEA Vishay Dale 0Ω Resistor, Size 0603, 5% 3 R15, R15A (9) CRCW04022K70JNED Vishay Dale 2.7kΩ Resistor, Size 0603, 1% 2 R16, R16A (9) CRCW0603100KFKEAHP Vishay Dale 100kΩ Resistor, Size 0603, 1% 2 R18, R18A (9) CRCW060349K9FKEA Vishay Dale 49.9kΩ Resistor, Size 0603, 1% 2 R21 CRCW060349R9FKEA Vishay Dale 49.9Ω Resistor, Size 0603, 1% 1 R23, R23A(9)) CRCW06031R21FKEA Vishay Dale 1.21Ω Resistor, Size 0603, 1% 2 R4, R10, R11, R19, R19A(9) U1, U1A(9) DNP MIC28304-1YMP MIC28304-2YMP Micrel. Inc.(16) 70V, 3A Power Module 2 Notes: 15. Vishay: www.vishay.com. 16. Micrel, Inc.: www.micrel.com. April 29, 2014 14 Revision 1.0 Micrel, Inc. MIC28304 Evaluation Board PCB Layout Recommendations MIC28304 Evaluation Board Top Layer MIC28304 Evaluation Board Mid-Layer 1 (Ground Plane) April 29, 2014 15 Revision 1.0 Micrel, Inc. MIC28304 Evaluation Board PCB Layout Recommendations (Continued) MIC28304 Evaluation Board Mid-Layer 2 MIC28304 Evaluation Board Bottom Layer April 29, 2014 16 Revision 1.0 Micrel, Inc. MIC28304 Evaluation Board MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com Micrel makes no representations or warranties with respect to the accuracy or completeness of the information furnished in this data sheet. This information is not intended as a warranty and Micrel does not assume responsibility for its use. Micrel reserves the right to change circuitry, specifications and descriptions at any time without notice. No license, whether express, implied, arising by estoppel or otherwise, to any intellectual property rights is granted by this document. Except as provided in Micrel’s terms and conditions of sale for such products, Micrel assumes no liability whatsoever, and Micrel disclaims any express or implied warranty relating to the sale and/or use of Micrel products including liability or warranties relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right. Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A 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 indemnify Micrel for any damages resulting from such use or sale. © 2014 Micrel, Incorporated. April 29, 2014 17 Revision 1.0 Micrel, Inc. MIC28304 Evaluation Board Revision History Date 2/15/14 Change Description/Edits by: Rev. New Eval Board literature April 29, 2014 1.0 18 Revision 1.0