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 the 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 centimeters from any other decoupling capacitor. The specified supply voltage range is between 2.7 V and 5.5 V while current consumption is dependent 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 a 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 the 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 push-pull 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.
The MAX7375 is a silicon oscillator, intended as a low-cost improvement replacing ceramic resonators, crystals, and crystal oscillator modules used as the clock source for microcontrollers and UARTs in 3V, 3.3V, and 5V applications.
The MAX7375 is a fully integrated oscillator, supplied at specific factory-trimmed frequencies with a rail-to-rail 50% duty cycle square-wave output. The oscillator frequency is generated directly without the use of a phase-locked loop (PLL). No additional components are used to set or adjust the frequency.