ZHCS547K January 2010 – February 2018 LM27402
PRODUCTION DATA.
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The current limit setpoint in this design is set at 25 A at 25°C, based on resistor RSET and the inductor DCR of 2.34 mΩ. Of course, the current limit setpoint must always be selected such that the operating current level does not exceed the saturation current specification of the chosen inductor. The component values for the DCR sense network (RS and CS in Figure 41) are chosen based on setting the RSCS product approximately equal to L/RDCR, as recommended in the Setting the Current Limit Threshold section. The MOSFETs are chosen for both lowest conduction and switching power loss, as discussed in detail in the Power MOSFETs section.
| DESIGNATOR | TYPE | PARAMETERS | PART NUMBER | QTY | MANUFACTURER |
|---|---|---|---|---|---|
| U1 | IC | Synchronous Buck Voltage-Mode PWM Controller | LM27402 | 1 | TI |
| CBOOT | Capacitor | 0.22 µF, Ceramic, X7R, 25 V, 10% | GRM188R71E224KA88D | 1 | Murata |
| CC1 | Capacitor | 3.9 nF, Ceramic, X7R, 50 V, 10% | GRM188R71H392KA01D | 1 | Murata |
| CC2 | Capacitor | 150 pF, Ceramic, C0G, 50 V, 5% | GRM1885C1H151JA01D | 1 | Murata |
| CC3 | Capacitor | 820 pF, Ceramic, C0G, 50 V, 5% | GRM1885C1H821JA01D | 1 | Murata |
| CVDD | Capacitor | 1 µF, Ceramic, X5R, 25 V, 10% | GRM188R61E105KA12D | 1 | Murata |
| CF | Capacitor | 1 µF, Ceramic, X5R, 25 V, 10% | GRM188R61E105KA12D | 1 | Murata |
| CIN | Capacitor | 22 µF, Ceramic, X5R, 25 V, 10% | GRM32ER61E226KE15L | 5 | Murata |
| COUT | Capacitor | 100 µF, Ceramic, X5R, 6.3 V, 20% | C1210C107M9PACTU | 4 | Kemet |
| CS | Capacitor | 0.22 µF, Ceramic, X7R, 25 V, 10% | GRM188R71E224KA88D | 1 | Murata |
| CSS | Capacitor | 47 nF, Ceramic, X7R, 16 V, 10% | GRM188R71C473KA01D | 1 | Murata |
| CSBY | Capacitor | 100 pF, Ceramic, C0G, 50 V, 5% | GRM1885C1H101JA01D | 1 | Murata |
| DBOOT | Diode | Schottky Diode, Average I = 100 mA, Max Surge I = 750 mA | CMOSH-3 | 1 | Central Semi |
| DSW | Diode | Schottky Diode, Average I = 3A, Max Surge I = 80A | CMSH3-40M | 1 | Central Semi |
| LOUT | Inductor | 0.68 µH, 2.34 mΩ | IHLP5050CEERR68M06 | 1 | Vishay |
| QL | N-CH MOSFET | 30 V, 60 A, 43.5 nC, RDS(on) at 4.5 V = 1.85 mΩ | Si7192DP | 1 | Vishay |
| QH | N-CH MOSFET | 25 V, 40 A, 13 nC, RDS(on) at 4.5 V = 6.2 mΩ | SiR436DP | 1 | Vishay |
| RC1 | Resistor | 8.06 kΩ, 1%, 0.1 W | CRCW06038k06FKEA | 1 | Vishay |
| RC2 | Resistor | 261 Ω, 1%, 0.1 W | CRCW0603261RFKEA | 1 | Vishay |
| RFADJ | Resistor | 45.3 kΩ, 1%, 0.1 W | CRCW060345K3FKEA | 1 | Vishay |
| RFB1 | Resistor | 20.0 kΩ, 1%, 0.1 W | CRCW060320K0FKEA | 1 | Vishay |
| RFB2 | Resistor | 13.3 kΩ, 1%, 0.1 W | CRCW060320K0FKEA | 1 | Vishay |
| RF | Resistor | 2.2 Ω, 5%, 0.1 W | CRCW06032R20JNEA | 1 | Vishay |
| RPGD | Resistor | 51.1 kΩ, 5%, 0.1 W | CRCW060351K1JNEA | 1 | Vishay |
| RS | Resistor | 1.3 kΩ, 1%, 0.1 W | CRCW06031K30FKEA | 1 | Vishay |
| RSET | Resistor | 6.34 kΩ, 1%, 0.1 W | CRCW06036K34FKEA | 1 | Vishay |