NanoBoard 3000 - PWM Power Drivers

The NanoBoard 3000 includes circuitry that allows PWM-driven power control systems to be easily realized. Four I/O pins of the User FPGA are wired to N-channel 'enhancement mode' metal-oxide semiconductor field-effect transistors (NMOSFETs) – catering for four independent power control/PWM channels.

Each NMOSFET device (an AO3400) supports a maximum Drain-Source voltage of 30V, with maximum continuous Drain current of 5.8A. In terms of switching, the maximum turn-on delay time is 5ns, with a maximum turn-off delay time of 40ns.

The four output signals ('PWM0' - 'PWM3') are delivered to a 6-way screw terminal block. This terminal block also provides 5V power and ground signals. The former is connected to the motherboard's 5V supply, via a 5A/15V Multifuse® PPTC resettable fuse (an MF-SM250, from Bourns). This fuse has a hold current of 2.5A, tripping at 5A.

PWM interface.

Each signal line from the User FPGA is protected against transient voltages (caused for example by ESD) through use of a TVS diode array device – an SMF05C, from Semtech.

An LED associated with each PWM channel is used to indicate channel activity, lighting (YELLOW – 120mcd) when the corresponding line from the User FPGA is taken High.

Location on Board

The NMOSFET device for each channel (designated Q5, Q1, Q2 and Q3 respectively), the screw terminal block (designated J16) and the SMF05C device for each channel (designated U22, U9, U10 and U11 respectively) are all located on the component side of the board, to the right of the ethernet status LEDs.

The channel activity LEDs (designated LED12, LED8, LED9 and LED10) and labeled '0' to '3' respectively) are located between the main PWM interface and the board's relays.

Channel activity LEDs for
the PWM interface.

The resettable fuse (designated F1) is located on the solder side of the board, below the connectors for the MIDI interface.

Schematic Reference

The PWM circuitry can be found on the following sheets of the motherboard schematics:

• Sheet 41 (PWM_5.8A_30V_X4.SchDoc, entitled PWM x 4)

• Sheet 42 (PWM_5.8A_30V.SchDoc, entitled PWM 30V/4A)

• Sheet 43 (CON_PWMx4_KMRJIO3_5MM_6WAY.SchDoc, entitled Screw Header For Power PWM)

Design Interface Component

Table 1 summarizes the available design interface component that can be placed from the FPGA NB3000 Port-Plugin.IntLib, to access and use the PWM interface.

Further Device Information

For more information on the AO3400 device, refer to the datasheet (AO3400.pdf) available at www.aosmd.com.

For more information on the SMF05C device, refer to the datasheet (SMF05C.pdf) available at www.semtech.com.

For more information on the MF-SM250 device, refer to the datasheet (mfsm.pdf) available at www.bourns.com.