Diodes PAM2842 User Manual

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Description

The PAM2842 is a high power LED driver, capable of driving up to 10

high power LEDs in series. The PAM2842 supports buck, boost and

sepic topology.

The PAM2842 features over current protection, over voltage

protection, under voltage lockout and over temperature protection,

which prevent the device from damage.

LED dimming can be done by using a PWM signal to the COMP pin.

The PAM2842 is available in TSSOP-20 packages.

Features

Pin Assignments

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PAM2842

HIGH POWER LED DRIVER

• Output Power up to 30W

• Chip Enable with Soft-start

• Analog and PWM Dimming

• Peak Efficiency up to 97%

• Low Quiescent Current

• Switching Frequency Adjustable

• Support Buck/Boost/Sepic Toplogy

• Over Current Protection

• Over Voltage Protection

• Thermal Protection

• UVLO

• Tiny Pb-Free Packages: 40-Pin QFN6x6 and TSSOP-20

Applications

• Home Lighting

• Automotive Lighting

• Monitor Backlighting

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Typical Applications Circuit

Boost with Low Side Current Sense Boost with High Side Current Sense

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PAM2842

Buck/Boost (Sepic) with Low Side Current Sense Buck/Boost (Sepic) with High Side Current Sense

Buck with High Side Current Sense

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Pin Descriptions

Name

QFN6x6-40 TSSOP-20

Pin Number

PGND 1 – 6 1, 2, 3, 4, 10, 11

HVIN 8 5

EN 9 6

VDD-DR 10 7

RT 12 8

AGND 13 9

Sense- 14 12

Sense+ 15 13

COMP 17 14

VDD_5V 21 15

OV 23 16 SW 25 – 30 17, 18, 19

NC

7, 11, 16, 18-20,

22, 24, 31-40

20

Functional Block Diagram

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PAM2842

Function

Power Ground

Input

Chip Enable, Active High

Internal LDO Output

Frequency Adjustment Pin

Analog Ground

Sense Resistor -

Sense Resistor+

Compensation Node

Internal LDO Output

Over Voltage

Drain of Main Switch

Not Connected

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PAM2842

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

Supply Voltage 40 V

Buck Application Maximum Output Current 3 A

I/O Pin Voltage Range

Maximum Junction Temperature 150

Storage Temperature -40 to +150

Soldering Temperature 300, 5sec

Recommended Operating Conditions (@T

Parameter Rating Unit

Supply Voltage Range 5.5 to 40 V

Operation Temperature Range -40 to +85

Junction Temperature Range -40 to +125

= +25°C, unless otherwise specified.)

A

GND -0.3 to V

A

+0.3

DD

= +25°C, unless otherwise specified.)

V

°C

Thermal Information

Parameter Package Symbol Max Unit

Thermal Resistance (Junction to Case)

Thermal Resistance (Junction to Ambient)

Note: 1. The exposed PAD must be soldered to a thermal land on the PCB.

Electrical Characteristics (@T

Parameter Test Conditions Min Typ Max Units

Input Voltage Range 5.5 40 V

Quiescent Current

Feedback Voltage, Low Side

Feedback Voltage, High Side

LED Current Line Regulation

LED Current Load Regulation 1.0 %

VDD_DR UVLO Hysteresis No Switching 200 mV

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TSSOP-20

QFN6x6-40 7.6 (Note 1)

TSSOP-20

QFN6x6-40 18.1 (Note 1)

= +25°C, VEN = VDD = 24V, 1W x 10 LEDs, unless otherwise specified.)

A

E NA = high (no switching frequency) 1 2 mA

E NA = high (1M switching frequency) 6 mA

E NA = high (500k switching frequency) 3 mA

E NA = high (200k switching frequency) 1.6 mA

E NA = low 5 10 µA

V

= V

FB

V

= V

FB

I

= 350mA

O

SENSE+

-AGND, V

– V

SENSE-

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SENSE-

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θ

JC

θ

JA

= AGND

20

90

95 100 105 mV

°C/W

0.02 %/V

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PAM2842

Electrical Characteristics (cont.) (@T

Parameter Test Conditions Min Typ Max Units

VDD_5V No Switching 4.5 5 5.5 V

VDD_5V Current Limit No Switching 14 74 90 mA

VDD_5V UVLO Threshold No Switching 3.7 4.0 4.3 V

VDD_5V UVLO Hysteresis No Switching 200 mV

VDD_DR No Switching 4.5 5 5.5 V

VDD_DR Current_Limit No Switching 14 50 90 mA

VDD_DR UVLO Threshold No Switching 3.7 4.0 4.3 V

Switch RDS(ON) VDD_5V = 5V 0.1 Ω

Switch Current Limit 3.5 A

Switch Leakage Current 50 µA

RT Voltage

Switching Frequency (Note 2)

Min Duty Cycle

Max Duty Cycle

VC Source Current Feedback Voltage = 0 30 µA

VC Sink Current Feedback Voltage = 0 30 µA

OV Threshold Voltage 1.1 1.2 1.3 V

OV Hysteresis 70 mV

Thermal Shutdown 150 °C

Thermal Shutdown Hysteresis 30 °C

EN High 1.5 V

EN Low 0.4 V

Note: 2. Switching frequency

F

SW

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R

RT

R

RT

RRT = 71kΩ

RRT = 180kΩ

F

SW

FSW = 500kHz

FSW = 200kHz

Low Side Sense 95 %

High Side Sense 100 %

10

=

(x24

R

= +25°C, VEN = VDD = 24V, 1W x 10 LEDs, unless otherwise specified.)

A

LDO Stage

Switch Stage

= 71kΩ

= 30kΩ

= 1MHz

12

+

RT

Fault Protection

Control Interface

, reference value.

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1.1 1.2 1.3 V

800k 1M 1.2M Hz

400 500 600 kHz

160 200 240 kHz

10 %

5 %

2.5 %

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Typical Performance Characteristics

Boost Mode, @TA = +25°C, VEN = VDD = 24V, 3W LEDs, FSW = 200kHz, unless otherwise specified.)

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