Technical data

Host interface 20/72

netRAPID Chip Carrier | Design Guide

4.2 General signals

4.2.1 Supply voltage

Only a single 3.3 V operation voltage is needed to operate the netRAPID. The voltage must be

regulated and can have a tolerance of ±5% (3.15 - 3.45 V) and must be connected twice to the

netRAPID chip carrier. The power has to be supplied between pins +3V3 and GND. To avoid EMI

problems use bypass capacitors in the power supply path. All other special voltages required on

the netRAPID are generated by onboard DC/DC converters.

A voltage supervisor circuit on all netRAPID devices supervises the voltage and the

microprocessor. If the voltage decreases below the voltage reset level of typically 2.93 V (2.85 -

3.00 V) the netRAPID is held in reset state. If the voltage exceeds the reset voltage threshold, the

netRAPID will begin with the power up sequence. To avoid problems with the power supply we

recommend using a voltage of 3.3 V. The operation will thus be in the safe range of the voltage

operation area, ensuring that short voltage drops, spikes and noise will not cause any reset

conditions.

The maximum power consumption depends on the netRAPID type. For power consumption values

see section Technical data on page 54.

4.2.2 Reset signal

It is possible to reset the netRAPID by the global power-on reset signal DPM_RESETn. As long as

the signal DPM_RESETn has high level, the netRAPID stays in operating mode.

The netRAPID is in reset mode when the signal DPM_RESETn has a static low level. To reset the

netRAPID the DPM_RESETn signal must be low for more than 10 µs. Afterwards, the netRAPID

starts the initialization and program execution. This power up time is different for each netRAPID

and loaded firmware.

Important:

During reset all signals of the dual-port memory are configured as inputs! The output

level could be floating.

If the host system needs a stable level, a pull-up or pull-down resistor is required on the

host system.

For details about the circuit for the host system see Figure 21: Schematic NRPEB-CCS and

NRPEB-DPS (Part 1) on page 62 or see Figure 23: Schematic NRPEB-RE2 (Part 1) on page 64.

Recommendation: Always add a push button to your

host system connected to the netRAPID

device to reset the netRAPID device. This reset button together with the mandatory push button (or

switch or an equivalent device) to activate the serial boot mode is important for your production,

because the serial boot mode is needed to load the Second Stage Boot Loader into the netRAPID

device.