Diodes PAM2863 User Manual

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PAM2863

2A LED DRIVER with INTERNAL SWITCH

Description

The PAM2863 is a continuous mode inductive step-down converter, designed for driving single or multiple series connected LEDs efficiently from a voltage source higher than the LED voltage. The device operates from an input supply between 4.5V and 40V and provides an externally adjustable output current of up to 2A. Depending upon supply voltage and external components, this can provide up to 30 watts of output power.

The PAM2863 includes the output switch and a high-side output current sensing circuit, which uses an external resistor to set the nominal average output current.

Output current can be adjusted below the set value, by applying an external control signal to the VSET pin.

The VSET pin will accept either a DC voltage or a PWM waveform.

The soft-start time can be increased using an external capacitor from the VSET pin to ground. Applying a voltage of 0.2V or lower to the VSET pin turns the output off and switches the device into a low current standby state.

Features

• Simple Low Parts Count

• Internal 40V NDMOS Switch

• 2A Output Current

• Single Pin On/Off and Brightness Control Using DC Voltage or

PWM

• Soft-Start

• High Efficiency (up to 97%)

• Wide Input Voltage Range: 4.5V to 40V

• Output Shutdown

• Open LED Protection

• Short LED Protection

• Up to 1MHz Switching Frequency

• Typical 5% Output Current Accuracy

• Pb-Free SOP-8(EP) Packages

Pin Assignments

Applications

• High End LED Flashlight

• LED Light Bar

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Typical Applications Circuit

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PAM2863

Pin Descriptions

Number

5, 6 LX Drain of NDMOS switch.

3, 7, 8 GND Ground (0V)

4 VSET

2 ISENSE Connect resistor RS from this pin to VIN to define nominal average output current IOUTnom = 0.1/Rs 1 VIN Input voltage (6V to 40V). Decouple to ground with 10F or higher X7R ceramic capacitor close to device.

PAM2863

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Name

Function

• Multi-function On/Off and brightness control pin:

• Leave floating for normal operation.

• Drive to voltage below 0.2V to turn off output current

• Drive with DC voltage (0.3V < VSET< 2.5V) to adjust output current from 12% to 100% of I

• Drive with PWM signal from open-collector or open-drain transistor, to adjust output current. Adjustment range 1% to 100% of I

• Connect a capacitor from this pin to ground to increase soft-start time. (Default soft-start time = 0.1ms. Additional soft-start time is approx.1.5ms/1nF)

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OUTnom

2 of 11

for f < 500Hz

OUTnom

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Functional Block Diagram

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PAM2863

Absolute Maximum Ratings (@T

These are stress ratings only and functional operation is not implied. Exposure to absolute maximum ratings for prolonged time periods may affect device reliability. All voltages are with respect to ground.

Parameter Rating Unit

Input Voltage Range -0.3 to +40

LX, I

VSET Pin Voltage -0.3 to +6.0

Maximum Junction Temperature 170

Storage Temperature -65 to +170

Soldering Temperature 300, 5sec

SENSE

Pin Voltage

Recommended Operating Conditions (@T

Parameter Rating Unit

Input Voltage Range 4.5 to 40 V

Ambient Temperature Range -40 to +85 °C

Junction Temperature Range -40 to +125 °C

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= +25°C, unless otherwise specified.)

A

-0.3 to +40

= +25°C, unless otherwise specified.)

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V

°C

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PAM2863

Thermal Information

Parameter Package Symbol Max Unit

Thermal Resistance (Junction to Ambient) SOP-8(EP)

Thermal Resistance (Junction to Case) SOP-8(EP)



JA



JC

Electrical Characteristics (@T

= +25°C, VIN = 16V, unless otherwise specified.)

A

Parameter Symbol Test Conditions Min Typ Max Units

Inout Voltage

Output Current

Shutdown Current

Quiescent Current without Switching

Mean Current Sense Threshold Voltage

Sense Threshold Hysteresis

ISENSE Pin Input Current

VSET Range on VSET Pin

DC Voltage on VSET Pin to Enable

DC Voltage on VSET Pin to Disable

LX Switch on Resistance

LX Switch Leakage Current

Soft-Start Time

Operating Frequency

Recommended Minimum Switch ON Time

Recommended Maximum Switch Frequency

V

IN

I

LED

I

SD

I

VSET Pin Floating, VIN = 16V

Q

V

SENSE

V

SENSE_HYS

I

SENSE

V

EN

V

EN(ON)

V

EN(OFF)

R

LX

I

LX(LEAK)

T

SS

F

LX

T

ON_REC

F

LX(MAX)

= 0.1

R

S

RS = 0.05

VSET Pin Grounded 20 40 µA

Measured on I Respect to V

±13 %

V

SENSE

IN

= VIN -0.1

For DC Dimming 0.3 2.5 V

VEN Rising

VEN Falling

@ILX = 100mA

5 µA

V

= 16V, CEN = 1nF

IN

V

= 16V, VO = 9.6V (3 LEDs),

IN

L = 47µH, I = 0.25A (I

For 4% Accuracy 500 Ns

1.0 MHz

Max Duty Circle 98 %

Recommended Duty Cycle Range

Internal Comparator Propagation Delay

Over Temperature Protection

Temp Protection Hysteresis

Current Limit

Note: 1. V Parameters are not tested at production, but guaranteed by design.

: LevelA: 95mV to 100mV; level B: 100mV to 105mV

SENSE

T

PD

T

I

D

LX

(Note 1)

T

OTP

OTP_HYS

XL(MAX)

25 75 %

45 Ns

150 °C

40 °C

Peak Inductor Current 2.5 A

90

11

Pin with

= 1A)

LED

°C/W

4.5 40 V

1 A

2 A

0.6 mA

95 100 105 mV

8 µA

0.25 V

0.2 V

0.3 

1.5 Ms

233 kHz

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