The LTC6903/LTC6904 are low power self contained digital frequency sources providing a precision frequency from 1kHz to 68MHz, set through a serial port. The LTC6903/LTC6904 require no external components other than a power supply bypass capacitor, and they operate over a single wide supply range of 2.7V to 5.5V. The LTC6903/LTC6904 feature a proprietary feedback loop that linearizes the relationship between digital control setting and frequency, resulting in a very simple frequency setting equation. The LTC6903 is controlled by a convenient SPI compatible serial interface. The LTC6904 uses an industry standard I2C compatible interface.
The LTC6903 and LTC6904 are low‑power, self‑contained digital frequency sources that generate square‑wave outputs from 1 kHz to 68 MHz. They operate from a single 2.7 V‑5.5 V supply and require only a bypass capacitor besides the power pins. Frequency is set via a serial interface – SPI for the LTC6903 and I²C‑compatible for the LTC6904.
Typical applications include precision timing, power‑management clocks, DDS replacement, and switched‑capacitor filter clocks. The devices feature a proprietary feedback loop that linearizes the digital‑to‑frequency relationship, providing 0.5 % typical initial frequency accuracy and low jitter across the range.
| Frequency range | 1 kHz – 68 MHz |
|---|---|
| Supply voltage | 2.7 V – 5.5 V |
| Typical supply current (f < 1 MHz, Vs = 2.7 V) | 1.7 mA |
| Initial frequency accuracy (typ) | 0.5 % |
| Frequency error over all settings | < 1.1 % |
| Frequency drift over temperature | 10 ppm/°C |
| High‑level output voltage (4 mA load) | 5.5 V |
The devices generate square‑wave outputs from 1 kHz up to 68 MHz.
They operate from a single supply of 2.7 V to 5.5 V.
Typical supply current is about 1.7 mA for frequencies below 1 MHz with a 2.7 V supply.