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Main description:

The S4422 series chip is a special chip for switching color temperature. The chip has a built-in 40V switch tube, which simplifies the peripheral circuit structure. This series of chips adopts the patented technology of Xinfeiling, which can not only simplify the number of peripheral components to the greatest extent, but also ensure the logic consistency when multiple power supplies are applied at the same time.

In order to expand the field of application, the S4422 series can be used in the isolated flyback, Buck or Buck-Boost structure to provide convenience for the design of the power supply.

Features:

? No need for any peripheral circuits

? Built-in 40V switch tube, no need for external switch tube

? There is no problem of logical disorder when multiple power supplies are used at the same time

? Built-in timer to ensure the consistency of time

? Compatible with isolated and non-isolated applications

? Patented technology, stable performance

Application:

? LED power supply for switching color temperature

Logical order:

The logical sequence of S4422 is L1->L2->L1+L2, where L1 and L2 represent the first and second LED light strings respectively

Function Description

1. Power supply

The S4422 is powered by the VCC pin. In the application, VCC is directly connected to the positive end of the output of the power supply, without any external components. Since the maximum withstand voltage of the VCC pin of S4422 is 67V, so

Therefore, in the application, the maximum output voltage of the power supply must be guaranteed to be less than 67V, otherwise the VCC pin of the S4422 will be easily broken down.

2. Detection

The current detection of S4422 is to detect the current flowing through D1 and D2 through the built-in current detection module. When the current flowing through D1 and D2 is lower than 30mA, S4422 considers that the power is off.

lamp.

3. Status control

S4422 detects the currents of D1 and D2 through the built-in current detection module. When it detects that the light is turned off, the internal state of S4422 will not switch to the next state immediately, but is allowed to switch to the next state after a delay of 20ms. If the switch is switched within 20ms, the state will not be switched to the next state, and the previous state will still be maintained.

4. Status retention time

In order to ensure the consistency of the time when the lights are turned off, the S4422 has a built-in timing module. When the S4422 detects that the light is turned off, the timing module starts timing, and the state retention time is about 9S, that is, when the light is turned off.

The state of S4422 can still be maintained within the last 9S, and when the light-off time exceeds 9S, the state of S4422 is reset to the initial state.

The working current of the S4422 during the state holding period is about 2uA, so in order to ensure that the state holding time is 9S, the output capacitor must be selected to be greater than or equal to 4.7uF.