SNVSCU3 October 2025 LM5137
PRODMIX
Table 8-6 shows the intended input, output, and performance parameters for this automotive circuit example.
| DESIGN PARAMETER | VALUE |
|---|---|
| Input voltage range (steady state) | 8V to 18V |
| Minimum transient input voltage | 6V |
| Maximum transient input voltage | 36V |
| Output voltage | 5V |
| Output current | 20A |
| Switching frequency | 2.1MHz |
| Output voltage regulation | ±1% |
| No-load sleep current with phase 2 disabled | < 20μA |
| Shutdown current | 4μA |
Resistor RRT of 10.5kΩ sets the switching frequency at 2.1MHz. In terms of control loop performance, the target loop crossover frequency is 80kHz with a phase margin greater than 50°. Leaving the RSS pin open sets the output voltage soft-start time to 6.5ms.
Table 8-7 cites the selected buck regulator powertrain components, with many of the components available from multiple vendors. Similar to circuit example 1, this design uses 40V logic-level MOSFETs, shielded buck inductors, shunt resistors with wide aspect ratio for low ESL, and an all-ceramic input and output capacitor implementation.
| REFERENCE DESIGNATOR | QTY | SPECIFICATION(1) | MANUFACTURER | PART NUMBER |
|---|---|---|---|---|
| CIN1, CIN2 | 4 | 10μF, 50V, X7R, 1210, ceramic | TDK | CNA6P1X7R1H106K |
| 10μF, 50V, X7S, 1210, ceramic | Murata | GCM32EC71H106KA03 | ||
| TDK | CGA6P3X7S1H106M | |||
| COUT1, COUT2 | 8 | 47μF, 6.3V, X7R, 1210, ceramic | Murata | GCM32ER70J476KE19L |
| Taiyo Yuden | JMK325B7476KMHTR | |||
| 47μF, 6.3V, X7S, 1210, ceramic | TDK | CGA6P1X7S0J476M | ||
| LO1, LO2 | 2 | 0.47μH, 2.2mΩ, 26.5A, 6.71 × 6.51 × 3.1mm | Coilcraft | XGL6030-471MEC |
| 0.47μH, 3mΩ, 25A, 6.95 × 6.6 × 4.3mm | Cyntec | VCUW064ER47MS5 | ||
| 0.47μH, 3.1mΩ, 20A, 7 × 6.9 × 3.8mm | Würth Electronik | 744311047 | ||
| 0.56μH, 3mΩ, 29A, 6.6 × 6.4 × 2.8mm | Bourns | SRP6030CA-R56M | ||
| Q1, Q3 | 2 | 40V, 4.7mΩ, 7nC, SON 5 × 6 | Infineon | IAUC60N04S6L039ATMA |
| Q2, Q4 | 2 | 40V, 3.6mΩ, 9nC, SON 5 × 6 | Infineon | IAUCN04S7L028ATMA |
| RS1, RS2 | 2 | Shunt, 4mΩ ±1%, ±50ppm/°C, 0612, 1.5W | Susumu | KRL3216E-C-R004-F |
| U1 | 1 | LM5137 80V two-phase synchronous buck controller | Texas Instruments | LM5137RHAR |