Diodes PAM2325 User Manual

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PAM2325

FAST TRANSIENT 3.5A STEP-DOWN CONVERTER

Description

The PAM2325 is a 3.5A step-down synchronous converter. The

1.2MHz switching frequency enables the use of small external

components. The ultra-small 2mm x 2mm footprint and high efficiency

make the PAM2325 an ideal choice for portable applications.

The PAM2325 delivers 3.5A maximum output current while

consuming only 55µA no load quiescent current. Low R integrated

MOSFETs and 100% duty cycle operation make the PAM2325 the

ideal choice for high output voltage, high current applications which

require a low dropout threshold.

The PAM2325 provides excel lent transient response and output

accuracy across the operating range.

The PAM2325 maintains high efficiency throughout the load range.

The PAM2325 automatically optimizes efficiency during light load

mode (PSM) and maintains constant frequency and low output ripple

during PWM mode.

Over-temperature and short circuit protection safeguard the PAM2325

and system components from damage.

The PAM2325 is available in an ultra-small QFN2x2-12 package. The

product is rated over a temperature range of -40°C to +85°C.

Applications

• Cellular Phone

• Digital Cameras

• Hard Disk Drives

• MP3 Players

• PDAs and Handheld Computers

• Portable Media Players

• USB Devices

• Wireless Network Cards

PAM2325

Document number: DSxxxxx Rev. 2 - 0

Pin Assignments

Features

• 3.5A Maximum Output Current

• Tiny 1.0µH Chip Inductor

• Excellent Transient Response

• Input Voltage: 2.5V to 5.5V

• Adjustable Output Voltage: 1.0V to 4.0V

• High Efficiency with 1.2MHz Switching Frequency

• 55µA No Load Quiescent Current

• 100% Duty Cycle Low-Dropout Operation

• Internal Soft Start

• Power Good Indicator

• Over-Temperature and Current Limit Protection

• Hiccup mode for output short protection

• 1µA Shutdown Current

• -40°C to +85°C Temperature Range

• Available in QFN2x2-12 Package

• RoHS/REACH Compliant

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Typical Applications Circuit

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PAM2325

Pin Descriptions

Number

1 PVIN Supply Voltage to power FETs. PVIN is connected to VIN internally.

2, 11 SW Switch Output. Pin 2 and 11 can be connected together.

3, 12 PGND Power Ground. Pin 3 and 12 can be connected together.

4 AGND Quiet ground for controller circuits

5 NC Leave this pin open. Do not connect it to ground.

6 OUT Input sense pin for output voltage

7 FB Feedback. An external resistor divider from the output to GND, tapped to the FB pin, sets the output voltage.

8 EN On/Off Control.

9 PG

10 VIN Supply Voltage to internal control circuitry. VIN is connected to PVIN internally.

Name

Function

Power Good Indicator. The output of this pin is an open drain with internal pull up resistor to VIN. PG is pulled up to VIN when the FB voltage is within 10% of the regulation level, otherwise it is LOW.

Functional Block Diagram

PAM2325

Document number: DSxxxxx Rev. 2 - 0

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PAM2325

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 -0.3 to +6.5 V

EN, FB Pin Voltage

SW Pin Voltage

Junction Temperature 150 °C

Storage Temperature Range -65 to +150 °C

Soldering Temperature 300, 5sec °C

Recommended Operating Conditions (@T

Parameter Rating Unit

Supply Voltage 2.5 to 5.5 V

Operation Temperature Range -40 to +85

Junction Temperature Range -40 to +125

= +25°C, unless otherwise specified.)

A

-0.3 to V

-0.3 to (V

+0.3)

IN

= +25°C, unless otherwise specified.)

A

V

°C

Thermal Information

Parameter Symbol Package Max Unit

Thermal Resistance (Junction to Case)

Thermal Resistance (Junction to Ambient)

θ

JC

θ

JA

PAM2325

Document number: DSxxxxx Rev. 2 - 0

QFN2x2-12 16

QFN2x2-12 80

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°C/W

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PAM2325

Electrical Characteristics

(@TA = +25°C, VIN = 3.3V, V

Parameter Symbol Test Conditions Min Typ Max Units

Input Voltage Range

UVLO Threshold

Output Voltage Accuracy

Regulated Feedback Voltage

PMOS Current Limit

Output Voltage Line Regulation LNR

Output Voltage Load Regulation LDR

Quiescent Current

Shutdown Current

Oscillator Frequency

Drain-Source On-State Resisitance

SW Leakage Current

Start-Up Time

PSM Threshold

EN Threshold High

EN Threshold Low

EN Input Current

Over Temperature Protection OTP 150 °C

OTP Hysteresis OTH 30 °C

Effciency η

Output Ripple Ripple

Output Transient Ripple

PG Pin Trigger Delay 90 µs

PG Pin Threshold (relative to V

PG Open Drain Impedance (PG = PV

)

IN

PG Open Drain Impedance (PG = Low)

PAM2325

Document number: DSxxxxx Rev. 2 - 0

= 1.2V, CIN = 20µF, CO = 20µF, L = 1µH, unless otherwise specified.)

OUT

IN

Rising

V

IN

Hysteresis 400 550 mV

-4.0 +4.0 %

No Load 0.591 0.60 0.609 V

FB

V

= 3.3V to 5.5V

IN

I

= 1mA to 2A

O

No Load 55 100 µA

Q

VEN = 0V

IDS = 100mA

1 µA

250 1000 µs

S

P MOSFET 40 70 mΩ

N MOSFET 30 50 mΩ

VIN = 3.3V, VO = 1.2V

1.2 V

EH

0.4 V

EL

VEN = 2V

= 10mA

I

O

V

f

R

DS(ON)

I

V

UVLO

OUT

V

I

LIM

I

SD

OSC

LSW

t

I

TH

V

I

EN

IO = 500mA to 1A

IO = 1.5A

IO = 2A

I

= 10mA

O

IO ≥ 300mA

= 20mA to 1A

I

O

IO = 20mA to 2A

OUT

V

PK-PK

)

±10 %

250K 500K Ω

100 Ω

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2.5 3.3 5.5 V

2.35 2.5 2.65 V

4.8 A

0.5 1 %/V

2 %

1 µA

1.0 1.2 1.6 MHz

250 mA

1.2 4 µA

75 81

85 90

%

80 89

-5 +5

-2 +2

-10 +10

-12 +12

%

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