JAJSOR8 September 2024 LM70840 , LM70860 , LM70880
PRODUCTION DATA
Table 7-3 shows the intended input, output, and performance parameters for this design example.
DESIGN PARAMETER | VALUE |
---|---|
Input voltage range (steady-state) | 24V to 60V |
Min transient input voltage (cold crank) | 15V |
Max transient input voltage (load dump) | 72V |
Output voltage | 12V |
Output current | 8A |
Switching frequency | 400kHz |
Output voltage regulation | ±1% |
Active current, no load | 12µA |
Shutdown current | 2.2µA |
Soft-start time | 3ms |
The switching frequency is set at 400kHz by resistor RRT The selected buck regulator powertrain components are cited in Table 7-4, and many of the components are available from multiple vendors. This design uses a low-DCR, metal-powder composite inductor, and ceramic output capacitor implementation.
REFERENCE DESIGNATOR | QTY | SPECIFICATION | MANUFACTURER | PART NUMBER |
---|---|---|---|---|
CIN | 4 | 4.7μF, 100V, X7S, 1210, ceramic | Murata | GCM32DC72A475KE02L |
TDK | CGA6M3X7S2A475K200 | |||
CO | 4 | 22µF, 25V, X7R, 1210, ceramic | Murata | GCM32EC71E226KE36 |
TDK | CGA6P3X7R1E226M | |||
LO | 1 | 6.8µH, 6.2mΩ, 16A, 11.3 × 10 × 10mm | Coilcraft | XGL1010-682MEC |
6.5μH, 10.5mΩ, 13A, 10.5 × 10.0 × 4.5mm | Würth Electronik | 784325065 | ||
RS | 1 | Shunt, 5mΩ, 0508, 1W | Susumu | KRL3216T4A-M-R005 |
U1 | 1 | LM708x0 80V buck converter | Texas Instruments | LM70880RRXR |