SwitchBlox Nano 5V Output Performance

Introduction

SwitchBlox Nano contains a 5V output that can be used for powering downstream devices. This page details basic characterisation tests that will be useful if you plan to use this 5V output in your application.

These tests relate to SwitchBlox Nano Revision C, D and E (current revision).

Test setup

• Ambient temperature = 20°C
• Airflow = 0 LPM
• SwitchBlox operation = Idle, no networking
• Input Voltage = 24V

0A Output Current

DC Level

Mean voltage = 4.91V

AC Coupled (to show ripple)

Peak to peak ripple = 135.2mV (2.7% of DC level)
Ripple frequency = 546.42Khz

Heat on board

Maximum heat after 3 minutes = 36°C (16°C rise from ambient)

1A Output Current

DC Level
Unchanged

AC Coupled (to show ripple)

Peak to peak ripple = 120mV (2.4% of DC level)
Ripple frequency = 546.42Khz

Heat on board

Maximum heat after 3 minutes = 79°C (59°C rise from ambient)

Summary of Results

The output ripple at both the 1A appears less than the ripple at 0A. This is likely because no-load conditions can cause higher oscillations on the output of a switching regulator. Ultimately the ripple seems bounded to around 140mV-200mV.

The frequency of the ripple is around 546KHz. This makes sense as the stated switching frequency of the onboard regulator is 555KHz.

Loads above around 1.1A resulted in the regulator voltage output dropping, causing SwitchBlox Nano to power off.

The temperature increase at 1A is significant, at around 59°C. This is one of the tradeoffs with the small size of this board, and is probably not easy to mitigate without external cooling (either a heatsink or increased airflow).