ST1CC40 datasheet(16/37 Pages) STMICROELECTRONICS

部件名	ST1CC40

功能描述	3 A monolithic step-down current source with synchronous rectification

PDF	37 Pages

Scroll/Zoom	100%

制造商	STMICROELECTRONICS [STMicroelectronics]

网页	http://www.st.com

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16 / 37 page

Application notes

ST1CC40

16/37

DocID18279 Rev 5

Figure 8 shows the equivalent circuit of the LED constant current generator.

Figure 8. Load equivalent circuit

As a consequence, the LED equivalent circuit gives the

LED(s) term correlating the output

voltage with the high impedance FB input:

Equation 13

6.5

Total loop gain

In summary, the open loop gain can be expressed as:

Equation 14

Example

Design specifications:

VIN = 12 V, VFW_LED = 3.5 V, nLED = 2, rLED = 1.1 , ILED = 700 mA, ILED RIPPLE = 2%

The inductor and capacitor value are dimensioned in order to meet the ILED RIPPLE

specifications (see Section 7.1.2 for output capacitor and inductor selection guidelines):

L = 10

H, COUT = 2.2 F MLCC (negligible ESR)



LED nLED



RSENSE

nLED rLED RSENSE



----------------------------------------------------------



GCO s

 A

0 s

 

LED nLED





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