DAC12.TXT MVS Box 850 Merrimack,NH 4/1/93 INTRODUCTION ------------ The DAC12 card is a 2 channel 12-bit Digital to Analog Converter with a maximum sample rate of 100 khz. Both channels have sharp cutoff low-pass filters for signal conditioning and noise reduction. A 5 volt precision voltage reference is available for use with external circuitry. The DAC12 output voltage range is -5v to +5v when the filter is bypassed. Voltages at the filter outputs are -10 to +10v. These ranges can be altered with external resistive dividers or amplifiers. Output voltage is determined by the value written to each channel. The lowest value occurs when 000h is written and the highest with FFFh. The DACs are double buffered so writing to the lower and upper bytes have no effect until the Load DAC register is written to. This way all 12 bits on both channels are updated at once. Dual sharp-cutoff active filters improve playback quality of stereo audio. They provide overshoot damping in precision servo control applications. The frequency rolls off at approximately 10hkz and they have a gain of 2. SPECIFICATIONS -------------- Block Diagram: PC BUS : ---- -5 to +5V DAC OUT A : : : 5V ------ : ------ : REF----------------: DAC : : : FILT : : : : CH A :---------: A :-- -10 to +10V FILT OUT A :---------:-----------: : ------ : : ------ : : : : ---- -5 to +5V DAC OUT B : : : : : ------ : ------ : -----------: DAC : : : FILT : : : CH B :---------: B :-- -10 to +10V FILT OUT B :---------------------: : ------ : ------ : I/O Connector pinout: 1 Ground 2 NC I/O Registers: 3 Ground 4 NC 160h = DAC Chan A LSB (D7-0) 5 Ground 6 DAC OUT A 161h = DAC Chan A MSB (D11-8)* 7 Ground 8 DAC OUT B 162h = DAC Chan B LSB (D7-0) 9 Ground 10 NC 163h = DAC Chan B MSB (D11-8)* 11 NC 12 FILT OUT B 164H = Load DAC register 13 NC 14 FILT OUT A *lower 4 bits only, upper don't care 15 NC 16 NC 17 NC 18 NC 19 NC 20 NC 21 NC 22 NC Base Address Jumpers: 23 NC 24 NC J1 J2 J3 J4 160h= 1-5 2-6 3-7 4-8* 25 NC 26 10V REF OUT o o o o 1A0h= 1-6 2-5 3-7 4-8 27 Ground 28 NC o o o o 260h= 1-5 2-6 3-8 4-7 29 NC 30 NC J5 J6 J7 J8 2A0h= 1-6 2-5 3-8 4-7 31 Ground 32 +5V OUT 320h= 1-8 2-6 3-7 4-5 33 -12V OUT 34 +12V OUT *default The DAC12 is often used with inexpensive PC motherboards and the MVS ROM Drive for embedded applications or portable computers. Using a right angle PC Bus Expander (part number BP4) allows cards to lie down flat. Everything can now fit into a compact low-profile case. The DAC12 has the same form factor as the MVS Single Board Computer. Corner holes are in the same position which simplifies mounting with standoffs. The PC Bus ends of the DAC12 and the SBC are connected with a passive backplane. This is constructed using 62 pin IDC connectors (part number MVCON1) and a short length of ribbon cable. Other PC adapter cards can be added on in the same way. LIMITED WARRANTY MVS will repair free of charge product suffering from manufacturing defects for a period of 5 years after shipping. This will be done only if it has been determined by MVS that the product has not been misused (improper voltages, physical alteration, etc.). Otherwise a minimum service charge is required. In either case it is necessary to contact MVS for a Returned Merchandise Authorization (RMA) number before shipping the unit.