Maxim (www.maxim-ic.com) has produced a completely self-contained TTLchip in a very small three-pin outline. The MAX7375 family of oscillators operates in the range of 1 MHz up to around 10 MHz, (depending on device suffix) and requires no external components. It may be necessary to fit a 100 nF decoupling capacitor across the supply pins if the chip is sited further than a few centimetres from any other decoupling capacitor. The specified supply voltage range is between 2.7 V and 5.5 V while current consumption is dependant on clock frequency; at 4 MHz the chip takes 4 mA while at 8 MHz this rises to 6.5 mA. The device is available in an SOT23 package outline (MAX7375AUR) or in the even smaller SC70 outline (MAX7375AXR). Note that the pin-out definitions for these two outlines are not identical, the functions of pins 1 and pin 2 are swapped. The accuracy of the output frequency is guaranteed to be within ±2 % of nominal with a supply voltage of 3 V.
Over the entire temperature range this rises to a maximum of ±4 %. This chip is currently available in a range of seven frequencies shown in the table below. The TTL pushpull output stage can sink and source up to 10 mA. The rise and fall times of the oscillator output are in the order of 5 ns while the mark-space ratio lies between 45 % and 57 %. The MAX7375 offers a smaller, more cost-effective and mechanically more robust alternative to the conventional crystal or ceramic filter type of oscillator. The device has a wide operating temperature range of –40 °C to +125 °C and this makes it particularly suitable for automotive applications.