Diodes PAM2804 User Manual

A

f

Description

Product Line o

Diodes Incorporated

PAM2804

1A STEP-DOWN CONSTANT CURRENT, HIGH EFFICIENCY LED DRIVER

Pin Assignments

The PAM2804 is a step-down constant current LED driver. When the

input voltage down to lower than LED forward voltage, then PAM2804

run into LDO mode.

The PAM2804 supports a range of input voltages from 2.5V to 6.0V,

allowing the use of a single Li+/Li-polymer cell, 3AA or 4AA cell, USB,

and other standard power sources.

The FB voltage is only 0.1V to achieve high efficiency.

PAM2804 employ internal power switch and synchronous rectifier to

minimize external part count and realize high efficiency.

During shutdown, the input is disconnected from the output and the

shutdown current is less than 1µA. Other key features include under-

voltage lockout to prevent deep battery discharge of the Li+ battery.

Features

• Efficiency up to 93%

• 180µA(typ) Quiescent Current

• Output Current: Up to 1A

• Internal Synchronous Rectifier

• 1.5MHz Switching Frequency

• Soft-Start

• Under-Voltage Lockout

• Short LED Protection

• Open LED Protection

• Thermal Shutdown

• 5-Pin Small TSOT25 Packages

• Pb-Free Package

Typical Applications Circuit

Top View

TSOT25

Applications

• 3AA or 4AA Batteries Powered Flashlight

• 1 Cell Li-Ion Battery Powered Flashlight

I

= 0.1/RS

PAM2804

Document number: DSxxxxx Rev. 2 - 0

LED

1 of 10

www.diodes.com

January 2013

A

f

Pin Description

Number

1

2 3 4

5 FB Feedback voltage to internal error amplifier, the threshold voltage is 0.1V.

Name

EN

GND Ground

SW The drains of the internal main and synchronous power MOSFET.

VIN Chip main power supply pin.

Enable control input. Force this pin voltage above 1.5V, enables the chip, and below 0.3V shuts down the device.

Function

Block Diagram

Product Line o

Diodes Incorporated

PAM2804

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 Pin Voltage -0.3 to +6.5

EN, FB Pin Voltage

SW Pin Voltage

Junction Temperature Range 150

Storage Temperature Range -65 to +150

Soldering Temperature 300, 5sec

PAM2804

Document number: DSxxxxx Rev. 2 - 0

= +25°C, unless otherwise specified.)

A

-0.3 to V

-0.3 to (V

IN

+0.3)

IN

2 of 10

www.diodes.com

V

°C

January 2013

A

f

Product Line o

Diodes Incorporated

PAM2804

Recommended Operating Conditions (@T

Parameter Rating Unit

Supply Voltage 2.5 to 6.0

Operation Temperature Range -40 to +85

Junction Temperature Range -40 to +125

= +25°C, unless otherwise specified.)

A

°C

Thermal Information

Parameter Symbol Package Max Unit

Thermal Resistance (Junction to Case)

Thermal Resistance (Junction to Ambient)

Internal Power Dissipation

Note: 1. The maximum output current for TSOT25 package is limited by internal power dissipation capacity as described in Application Information herein after.

θ

JC

θ

JA

P

D

TSOT25 (Note 1) 130

TSOT25 250

TSOT25 400 mW

°C/W

Electrical Characteristics

(@TA = +25°C, VIN = 4.2V, Real WLED load, L = 4.7µH, CIN = 10µF, CO = 10µF, unless otherwise specified.)

Parameter Symbol Test Conditions Min Typ Max Units

Input Voltage Range

Regulated Feedback Voltage

Peak Inductor Current

Quiescent Current

Shutdown Current

Oscillator Frequency

Drain-Source On-State Resistance

SW Leakage Current

High Efficiency η 93 %

EN Threshold High

EN Threshold Low

EN Leakage Current

Over Temperature Protection OTP 150 °C

OTP Hysteresis OTH 30 °C

V

f

R

DS(ON)

I

V

I

OSC

LSW

I

PAM2804

Document number: DSxxxxx Rev. 2 - 0

IN

0.095 0.100 0.105 V

FB

VIN = 5V

PK

No Load

I

Q

VEN = 0V

SD

VO = 100%

IDS = 100mA

±0.01 1 µA

1.5 V

EH

0.3 V

EL

±0.01 µA

EN

www.diodes.com

P MOSFET 0.30 0.45 Ω N MOSFET 0.35 0.50 Ω

3 of 10

2.5 6.0 V

1.5 A

180 µA

1 µA

1.2 1.5 1.8 MHz

January 2013