CS1500 datasheet(11/22 Pages) CIRRUS

11 / 22 page

CS1500

DS849A7

Jul ?$shortyear>

CONFIDENTIAL

greater than the peak of the line voltage (Vrect(pk)). The

maximum response time of open/short loop protection for RFB

is about 150

μs in the CS1500.

If the PFC input sense resistor RAC fails (open or short to

GND), the current reference signal supplied to the IC on pin

IAC falls to zero. This failure is equivalent to a brownout

condition and will be handled by the brownout protection

mechanism described in Section 3.8.

3.12 Overcurrent Limiting

Boost inductor saturation is a fatal condition for a PFC

converter. To prevent inductor current saturation conditions,

the IC utilizes a proprietary digital algorithm that keeps the

boost inductor current away from its saturation current. The

boost inductor should be designed for full load, minimal line

voltage, maximum switching frequency, and with enough

margin to prevent saturation in normal operation mode.

3.13 Standby (STBY) Function

The standby (STBY) pin provides a means by which an

external signal can cause the CS1500 to enter into a non-

operating, low-power state. The STBY input is intended to be

driven by an open-collector/open-drain device. Internal to the

pin, there is a pull-up resistor connected to the VDD pin as

shown in Figure 20. Since the pull-up resistor has a high

impedance, the user may need to provide a filter capacitor (up

to 1000 pF) on this pin.

Figure 20. STBY Pin Connection

When the STBY pin is not used, it is recommended that the pin

be tied to VDD (pulled high).

<1 nF

600 k

See Text

VDD

STBY

GND

CS1500

CS1500 Datasheet(PDF) 11 Page - Cirrus Logic