NCP5050(2007) 查看數據表（PDF） - ON Semiconductor

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NCP5050
(Rev.:2007)

4.5 W Flash White LED Boost Driver

ON Semiconductor 

NCP5050

PIN FUNCTION DESCRIPTION

Pin

Pin Name

Type

Description

1 PGND

POWER

Power Ground: This pin is the power ground and carries the high switching current. A high quality

ground must be provided to avoid any noise spikes/uncontrolled operation. Cares must be observed to

avoid high-density current flow in a limited PCB copper track.

2

VS

3 CTRL

INPUT

INPUT

Voltage Sense: In order to sense Vout notably for over voltage protection, this input must be

connected to the output bypass capacitor Cout.

Control and Enable: An active high logic level on this pin enables the device. A built-in pulldown

resistor disables the device if the pin is left open. Also in disable condition the device provide a true

cut-off thank to the high impedance on FB input. This pin can also be used to control the average

current into the load by applying a low frequency PWM signal. If a PWM signal is applied, the

frequency should be high enough to avoid optical flicker but be no greater than 50 kHz.

4

CM

INPUT

Current Mode: An active high logic on this input enables the High Current Sense used for flash and

disables the LCS resistor. This pin has a low voltage threshold so it can be driven directly from 1.8 V

logic signals. If this function is not needed, this pin should be grounded. Only when CM pin is high, a

safety function switch off the output if CTRL pin is high longer than 1.2 s

5

PCA

INPUT

Peak Current Adjust: A resistor between this input and ground controls the maximum peak current

allowed in the inductor. The minimum value for this resistor is 2.8 kW and increasing this value

decreases the peak current. This allows the user to adjust the current based on the application needs

and scale the size of the inductor accordingly. See “Switch Current Limit” guidelines in application

section.

6

HCS

INPUT

High Current Sense: This pin is used for Flash Mode. If the user desires two levels of LED current

then a resistor should be connected from this pin to ground. This function is controlled by the CM input.

7

FB

INPUT

Feedback: The reference is 250 mV. This pin provides the feedback voltage by means of the sense

resistors fixed by LCS or HCS pin. When the device is enables and CM low, the LCS resistor is

connected to this pin, thereby the LCS setup the LED current. The tolerance of the LED current is

dependant upon the accuracy of this sense resistor and a $1% metal film resistor, or better, is

recommended for best output accuracy.

8

LCS

INPUT

Low Current Sense: This pin is used for Torch Mode. In order to fix the current when CM logic pin is

low, a resistor should be connected from this pin to ground.

9

PVIN

POWER Power Supply: The external voltage supply is connected to this pin. A 4.7 mF / 6.3 V high quality

capacitor must be connected across this pin and the power ground to achieve the specified output

power parameters. The X5R low DC/C versus DC bias ceramic types are highly recommended.

10

SW

INPUT

Switch: Power switch connection for inductor. Typical application will use a coil from 2.2 mH - 4.7 mH

and must be capable of handling the peak current.

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