ZHCSQT7E October 2001 – July 2022 DCR010503 , DCR010505 , DCR011203 , DCR011205 , DCR012403 , DCR012405
PRODUCTION DATA
When more than one DC/DC converter is switching in an application, beat frequencies and other electrical interference can be generated. This interference occurs because of the small variations in switching frequencies between the DC/DC converters.
The DCR01 series of devices overcome this interference by allowing devices to be synchronized to one another. Synchronize up to eight devices by connecting the SYNC pins of each device, taking care to minimize the capacitance of tracking. Stray capacitance (greater than 3 pF) reduces the switching frequency, or can sometimes stop the oscillator circuit. The maximum recommended voltage applied to the SYNC pin is 3 V.
For an application that uses more than eight synchronized devices, use an external device to drive the SYNC pins. The External Synchronization of the DCP01/02 Series of DC/DC Converters application report describes this configuration.
During the start-up period, all synchronized devices draw maximum current from the input simultaneously. If the input voltage falls below approximately 4 V, the devices may not start up. A ceramic capacitor must be connected close to the input pin of each device. Use a 2.2-μF capacitor for 5-V input devices, and a 0.47-μF capacitor for the 12-V and 24-V devices.