ZHCSLO5B December 2020 – December 2021 LM25149
PRODUCTION DATA
Table 9-3 shows the intended input, output, and performance parameters for this design example. Reference the LM25149-Q1EVM-2100 evaluation module.
| DESIGN PARAMETER | VALUE |
|---|---|
| Input voltage range (steady-state) | 8 V to 18 V |
| Min transient input voltage | 5.5 V |
| Max transient input voltage | 36 V |
| Output voltage | 5 V |
| Output current | 8 A |
| Switching frequency | 2.1 MHz |
| Output voltage regulation | ±1% |
| Standby current, no-load | 12 μA |
| Shutdown current | 2.3 μA |
| Soft-start time | 3 ms |
The switching frequency is set at 2.1 MHz by resistor RRT. In terms of control loop performance, the target loop crossover frequency is 60 kHz with a phase margin greater than 50°.
The selected buck regulator powertrain components are cited in Table 9-4, and many of the components are available from multiple vendors. The MOSFETs in particular are chosen for both lowest conduction and switching power loss, as discussed in detail in Section 9.1.1.4. This design uses a low-DCR metal-powder composite inductor and ceramic output capacitor implementation.
| REFERENCE DESIGNATOR | QTY | SPECIFICATION | MANUFACTURER | PART NUMBER |
|---|---|---|---|---|
| CIN | 2 | 10 μF, 50 V, X7S, 1210, ceramic | Taiyo Yuden | UMJ325KB7106KMHT |
| Murata | GCM32EC71H106KA03 | |||
| TDK | CGA6P3X7S1H106K250AB | |||
| CO | 4 | 47 μF, 6.3 V, X7R, 1210, ceramic | Murata | GCM32ER70J476KE19L |
| Taiyo Yuden | JMK325B7476KMHTR | |||
| 47 μF, 10 V, X7S, 1210, ceramic | TDK | CGA6P1X7S1A476M250AC | ||
| LO | 1 | 0.68 μH, 2.9 mΩ, 15.3 A, 6.7 × 6.5 × 3.1 mm | Coilcraft | XGL6030-681MEB |
| 0.56 μH, 3.6 mΩ, 13 A, 6.6 × 6.6 × 4.8 mm | Würth Electronik | 744373490056 | ||
| 0.68 μH, 4.5 mΩ, 22 A, 6.95 × 6.6 × 2.8 mm | Cyntec | VCMV063T-R68MN2T | ||
| Q1 | 1 | 40 V, 4.7 mΩ, 12 nC, SON 5 × 6 | Texas Instruments | CSD18503Q5A |
| Q2 | 1 | 40 V, 2.7 mΩ, 35 nC, SON 5 × 6 | Texas Instruments | CSD18511Q5A |
| RS | 1 | Shunt, 5 mΩ, 0508, 1 W | Susumu |
KRL2012E-M-R005-F-T5 |
| U1 | 1 | LM25149 42-V synchronous buck controller with AEF | Texas Instruments | LM25149RGYR |