L9680 datasheet(50/277 Pages) STMICROELECTRONICS

50 / 277 page

Start-up and power control

L9680

50/277

DocID029257 Rev 1

6.12

Oscillators

The device integrates two trimmed oscillators, both of them with spread spectrum capability

selectable via the CLK_CNF register.

The main oscillator runs at 16 MHz typ and is used to provide clock to the internal

synchronous logic. Moreover, this frequency is divided down by factor 8.5 to generate

clocks for the switching regulators (1.882 MHz typ).

The auxiliary oscillator runs at 7.5 MHz typ and is used to monitor the main oscillator. In

case the main oscillator frequency was lower than fOSC_LOW_TH threshold or higher than

fOSC_HIGH_TH threshold, the condition is detected by the frequency monitor circuit and then

latched into the CLKFRERR flag in the FLTSR register and a POR is issued.

6.13

Reset control

The device provides reset logic to safely control system operation in the event of internal

ECU failures. Several internal reset signals are generated depending on the type of failure

detected. In Figure 25 the voltage monitoring diagram is shown.

Figure 25. Internal voltage monitors

An active low pin output (RESET pin) is driven from the L9680 to allow resetting of external

devices such as the microcontroller, sensors, and other ICs within the ECU.

L9680 Datasheet(PDF) 50 Page - STMicroelectronics