ADSP-CM41x Power Supply Transistor Selection Guidelines (EE-390)
Technical guidelines for selecting external transistors and diodes for the integrated voltage regulator in Analog Devices ADSP-CM41x mixed-signal control processors.
Overview
This Engineer-to-Engineer Note (EE-390) provides design requirements for the external components used by the ADSP-CM41x processor's on-chip linear voltage regulator. The regulator generates a 1.21V core supply (VDD_INT) from a 3.3V input. The document specifies criteria for the external PNP bipolar junction transistor, including a recommended minimum Beta of 150 and power handling capabilities for current loads up to 400 mA. It also details Schottky diode selection to maintain proper voltage differentials and decoupling capacitor requirements (10 uF – 220 uF) with specific ESR for stability. Example components discussed include the DXTP19020DP5 transistor and VS-30BQ015PbF diode, alongside thermal calculation methods for various operating environments.
Use Cases
- Selecting external pass transistors for ADSP-CM41x internal regulators
- Designing power management circuits for ARM Cortex-M4/M0 control processors
- Calculating thermal dissipation for power supply components
- Ensuring voltage regulator stability through ESR management
Referenced Parts
DXTP19020DP5
Diodes Incorporated
With the above criteria, the DXTP19020DP5 transistor[3], with the following specifications, is selected
VS-30BQ015PbF
Vishay Semiconductors
VS-30BQ015PbF Schottky Rectifier, 3.0 A, Data Sheet.
ADSP-CM413F
Analog Devices
ADSP-CM411F/412F/413F/416F/417F/418F/419F Mixed-Signal Dual-Core Processor
| ADSP-CM411F | Analog Devices | ADSP-CM411F/412F/413F/416F/417F/418F/419F Mixed-Signal Dual-Core Processor |
| ADSP-CM412F | Analog Devices | ADSP-CM411F/412F/413F/416F/417F/418F/419F Mixed-Signal Dual-Core Processor |
| ADSP-CM416F | Analog Devices | ADSP-CM411F/412F/413F/416F/417F/418F/419F Mixed-Signal Dual-Core Processor |
| ADSP-CM417F | Analog Devices | ADSP-CM411F/412F/413F/416F/417F/418F/419F Mixed-Signal Dual-Core Processor |
| ADSP-CM418F | Analog Devices | ADSP-CM411F/412F/413F/416F/417F/418F/419F Mixed-Signal Dual-Core Processor |
| ADSP-CM419F | Analog Devices | ADSP-CM411F/412F/413F/416F/417F/418F/419F Mixed-Signal Dual-Core Processor |
| DXTP19020DP5 | Diodes Incorporated | With the above criteria, the DXTP19020DP5 transistor[3], with the following specifications, is selected |
| VS-30BQ015PbF | Vishay Semiconductors | VS-30BQ015PbF Schottky Rectifier, 3.0 A, Data Sheet. |
| ADSP-CM413F | Analog Devices | ADSP-CM411F/412F/413F/416F/417F/418F/419F Mixed-Signal Dual-Core Processor |