The devices, branded Chorus, include a MEMS resonator, oscillator and safety mechanisms into a single package that operates across -40 to 125°C and provides up to four configurable differential, or up to eight single-ended, low skew outputs.
“It is PCI Express Generation 1 to 6 compliant, with spread-spectrum options and on-chip regulators for power supply noise rejection, and is phase-configurable with programmable skew outputs”, said SiTime.
Monitored sub-systems include the MEMS oscillator, bandgap, PLL lock, clocks, Vdd and die temperature.
The external safety manager MCU is alerted via configurable GPIO pins, and a serial interface (I2C or SPI) is available to read internal internal monitoring status via internal registers – the serial bus also allows in-system re-configuration.
Packaged in a 4 x 4mm QFN, frequency is programmable over 1 to 700MHz, with typically 70fs phase jitter across 12kHz to 20MHz in the high specification SiT91283 version.
Stability is ±50ppm across the full operating temperature range, which improves to ±20ppm if maximum temperature is kept below 105°C.
Output choice is LVPECL, FlexSwing, LVDS, HCSL or LPHCSL in differential interfaces, or LVCMOS for single-ended options.
| Device | Output count |
Serial interface | Output types |
Jitter (rms typ) | Output range |
|---|---|---|---|---|---|
| SiT91281 | 8 single 4 diff |
I2C or SPI | LVDS, FlexSwing, LPHCSL,LVPECL, HCSL, LVCMOS |
150fs | 1 to 700MHz (diff) 1 to 220MHz (LVCMOS) |
| SiT91283 | 8 single 4 diff |
I2C or SPI | LVDS, FlexSwing, LPHCSL, LVPECL, HCSL, LVCMOS |
70fs | 1 to 700MHz (diff) 1 to 220MHz (LVCMOS) |
| SiT91288 | 8 single 4 diff PLL bypass |
I2C or SPI | LVDS, FlexSwing, LPHCSL, LVPECL, HCSL, LVCMOS |
150fs | 1 to 700MHz (diff) 1 to 220MHz (LVCMOS) |
| SiT91285 | 8 single 4 diff |
– | LVCMOS, HCSL, LPHCSL | 200fs | 24, 25, 38.4, 40, 48, 50, 100, 125, or 156.25MHz |
Supply can be 1.8V, 2.5V, or 3.3V.
Find the SiT91283 on this web page
