Rabbit RabbitCore RCM4400W Product Manual - page 119

OEM User’s Manual

111

C.1.3  Reset Generator

The RCM4400W uses a reset generator to reset the Rabbit 4000 microprocessor when the 

voltage drops below the voltage necessary for reliable operation. The reset occurs between 

2.85 V and 3.00 V, typically 2.93 V.

The RCM4400W has a reset output, pin 3 on header J1.

C.1.4  Onboard Power Supplies

The +3.3 V supplied to the RCM4400W via header J1 powers most of the onboard circuits. 

In addition, there is a +1.8 V DC linear regulator that provides the core voltage to the Rabbit 

4000 microprocessor. Other linear regulators supply the additional voltage levels needed by 

the Wi-Fi circuits. A /DISABLE line from the Rabbit 4000 can be used to disable the Wi-Fi 

linear regulators, essentially turning off the Wi-Fi circuits. The 

POWERDOWN.C

 sample 

program in the 

SAMPLES\RCM4400W\TCPIP\

 folder demonstrates this functionality.

Figure C-3.  RCM4400W Onboard Power Supplies

Voltage

Power Supply Use

+2.90 V DC

VDD_PA

+2.80 V DC

VDD_VCO

VDD_XCVR

+2.50 V DC

FPGA VCCAUX

+1.2 V DC

FPGA VCCINT

+ 1.8 V DC

U2

Regulated

+ 3.3 V DC

+ 2.80 V DC

U3

/DISABLE

Wi-Fi

+ 2.90 V DC

U15

+ 1.2 V DC

U4

+ 2.5 V DC

U16