Diodes AUR9713 User Manual

1.5MHz, 1A, STEP DOWN DC-DC CONVERTER AUR9713

Data Sheet

General Description

The AUR9713 is a high efficiency step-down DC-DC voltage converter. The chip operation is optimized using constant frequency, peak-current mode architecture with built-in synchronous power MOS switchers and internal compensators to reduce external part counts. It is automatically switching between the normal PWM mode and LDO mode to offer improved system power efficiency covering a wide range of loading conditions.

The oscillator and timing capacitors are all built-in providing an internal switching frequency of

1.5MHz that allows the use only small surface mount inductors and capacitors for portable product implementations. Additional features included integrated Soft Start (SS), Under Voltage Lock OUT (UVLO).

The device is available in adjustable output voltage versions ranging from 1V to 3.3V, and is able to deliver up to 1A.

The AUR9713 is available in TSOT-23-5 package.

Features

• High Efficiency Buck Power Converter

• Low Quiescent Current

• Output Current: 1A

• Adjustable Output Voltage from 1V to 3.3V

• Wide Operating Voltage Range: 2.5V to 5.5V

•

Built-in Power Switches for Synchronous

Rectification with High Efficiency

• Feedback Voltage: 600mV

• 1.5MHz Constant Frequency Operation

• Automatic PWM/LDO Mode Switching Control

• Thermal Shutdown Protection

• Low Drop-out Operation at 100% Duty Cycle

• No Schottky Diode Required

Applications

• Mobile Phone, Digital Camera and MP3 Player

• Headset, Radio and Other Hand-held Instrument

• Post DC-DC Voltage Regulation

• PDA and Notebook Computer

TSOT-23-5

Figure 1. Package Type of AUR9713

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Data Sheet

1.5MHz, 1A, STEP DOWN DC-DC CONVERTER AUR9713

Pin Configuration

H Package

(TSOT-23-5)

EN

GND

LX

Figure 2. Pin Configuration of AUR9713 (Top View)

1

2

34

5

FB

VIN

Pin Description

Pin Number Pin Name Function

1 EN Enable signal input, active high

2 GND

3 LX Connected to inductor

This pin is the GND reference for the NMOS power stage. It must be connected to the system ground

4 VIN Power supply input

5 FB Feedback voltage from the output

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Data Sheet

1.5MHz, 1A, STEP DOWN DC-DC CONVERTER AUR9713

Functional Block Diagram

Figure 3. Functional Block Diagram of AUR9713

Ordering Information

AUR9713

Circuit Type

A: Adjustable Output

Package

TSOT-23-5 -40 to 80°C AUR9713AGH 9713AG Tape & Reel

Temperature

Range

Part Number Marking ID Packing Type

BCD Semiconductor's Pb-free products, as designated with "G" in the part number, are RoHS compliant and green.

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Package H: TSOT-23-5 G: Green

Data Sheet

1.5MHz, 1A, STEP DOWN DC-DC CONVERTER AUR9713

Absolute Maximum Ratings (Note 1)

Parameter Symbol Value Unit

Supply Input Voltage VIN

Enable Input Voltage VEN

Output Voltage V

Power Dissipation (On PCB, TA=30°C) PD

Thermal Resistance (Junction to Ambient, Simulation) θJA

Thermal Resistance (Junction to Case, Simulation) θJC

Operating Junction Temperature TJ

Operating Temperature TO

Storage Temperature TS

ESD (Human Body Model) V

ESD (Machine Model) VMM

Note 1: Stresses greater than those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under “Recommended Operating Conditions” is not implied. Exposure to “Absolute Maximum Ratings” for extended periods may affect device reliability.

OUT

HBM

0 to 6.5

-0.3 to VIN+0.3

0.96

98.4

35.2

160

-40 to 85

-55 to 150

2000

200

V

W

°C/W

°C

V

Recommended Operating Conditions

Parameter Symbol Min Max Unit

Supply Input Voltage VIN 2.5 5.5 V

Junction Temperature Range TJ -20 125 °C

Ambient Temperature Range TA -40 80 °C

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Data Sheet

1.5MHz, 1A, STEP DOWN DC-DC CONVERTER AUR9713

Electrical Characteristics

VIN=3.6V, V

Parameter Symbol Conditions Min Typ Max Unit

Input Voltage Range VIN 2.5 5.5 V

=2.5V, V

OUT

=0.6V, L=2.2µH, CIN=4.7µF, C

REF

=10µF, TA=25°C, I

OUT

MAX

=1A.

Shutdown Current I Regulated1Feedback

Voltage Regulated Output Voltage Accuracy

∆V

Peak Inductor Current

Oscillator Frequency f

PMOSFET RON R

NMOSFET RON R

Quiescent Current IQ I

LX Leakage Current ILX

V

OFF

For Adjustable Output Voltage 0.585 0.6 0.615 V

V

FB

OUT/VOUT

I

OSC

ON(P)

ON(N)

PK

V

VIN=3.6V, I

VIN=2.5V, I

=0 0.1 1 µA

EN

=2.5V to 5.5V;

V

IN

=0 to 1A

I

OUT

V

=3V, VFB=0.5V or

IN

=90%, Duty Cycle＜35%

V

OUT

=3.6V 1.2 1.5 1.8 MHz

IN

=200mA 0.28 Ω

OUT

=200mA 0.38 Ω

OUT

=0mA, VFB=V

LOAD

=5V, VEN=0V, VLX=0V or

V

IN

+5% 100 µA

REF

5V

-3 3 %

1.5 A

0.01 0.1 µA

Feedback Current IFB 30 nA

EN Leakage Current IEN 0.01 0.1 µA EN High-level Input

Voltage EN Low-Level Input Voltage Under Voltage Lock Out

VIN=2.5V to 5.5V 1.5 V

V

EN_H

V

EN_L

=2.5V to 5.5V 0.6 V

IN

1.8 V

Hysteresis 0.1 V

Thermal Shutdown TSD 150 °C

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Data Sheet

1.5MHz, 1A, STEP DOWN DC-DC CONVERTER AUR9713

Typical Performance Characteristics

Figure 4. Efficiency vs. Output Current Figure 5. Efficiency vs. Load Current

Figure 6. Efficiency vs. Load Current Figure 7. LDO Mode Efficiency vs. Load Current

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Data Sheet

1.5MHz, 1A, STEP DOWN DC-DC CONVERTER AUR9713

Typical Performance Characteristics (Continued)

Figure 8. Output Voltage vs. Output Current

Figure 10. Output Voltage vs. Temperature Figure 11. Frequency vs. Temperature

Figure 9. UVLO Threshold vs. Temperature

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Data Sheet

1.5MHz, 1A, STEP DOWN DC-DC CONVERTER AUR9713

Typical Performance Characteristics (Continued)

Figure 12. Frequency vs. Input Voltage Figure 13. Output Current Limit vs. Temperature

V

OUT

200mV/div

VLX

2V/div

VEN

2V/div

Time 400ns/div

Figure 14. Frequency vs. Input Voltage Figure 15. Waveform of V

=4.5V, V

IN

=1.5V, L=2.2µH

OUT

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Data Sheet

1.5MHz, 1A, STEP DOWN DC-DC CONVERTER AUR9713

Typical Performance Characteristics (Continued)

VEN

2V/div

V

OUT

1V/div

V

LX

2V/div

Time 200µs/div

Figure 16. Soft Start

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Data Sheet

1.5MHz, 1A, STEP DOWN DC-DC CONVERTER AUR9713

Application Information

The basic AUR9713 application circuit is shown in Figure 18, external components selection is determined by the load current and is critical with the selection of inductor and capacitor values.

1. Inductor Selection

For most applications, the value of inductor is chosen based on the required ripple current with the range of

2.2µH to 4.7µH.

I −

1

=∆

V

OUTL

Lf

×

The largest ripple current occurs at the highest input voltage. Having a small ripple current reduces the ESR loss in the output capacitor and improves the efficiency. The highest efficiency is realized at low operating frequency with small ripple current. However, larger value inductors will be required. A reasonable starting point for ripple current setting is △I maximum ripple current stays below a specified value, the inductor should be chosen according to the following equation:

=

L

V

[

OUT

MAXIf

∆×

L

The DC current rating of the inductor should be at least equal to the maximum output current plus half the highest ripple current to prevent inductor core saturation. For better efficiency, a lower DC-resistance inductor should be selected.

2. Capacitor Selection

The input capacitance, CIN, is needed to filter the trapezoidal current at the source of the top MOSFET. To prevent large ripple voltage, a low ESR input capacitor sized for the maximum RMS current must be used. The maximum RMS capacitor current is given by:

It indicates a maximum value at V I

RMS=IOUT

commonly used for design because even significant

Mar. 2012 Rev. 1. 1 BCD Semiconductor Manufacturing Limited

II

×=

OMAXRMS

/2. This simple worse-case condition is

V

OUT

)1(

V

IN

=40%I

L

V

1][

)(

V

OUT

−

MAXV

IN

VVV

)]([ −

OUTINOUT

IN

=2V

IN

1

2

MAX

]

)(

OUT

. For a

, where

deviations do not much relieve. The selection of C is determined by the Effective Series Resistance (ESR) that is required to minimize output voltage ripple and load step transients, as well as the amount of bulk capacitor that is necessary to ensure that the control loop is stable. Loop stability can be also checked by viewing the load step transient response as described in the following section. The output ripple, △V

, is determined by:

OUT

[

ESRIV

LOUT

+∆≤∆

8

1

××

]

Cf

OUT

The output ripple is the highest at the maximum input voltage since △I

increases with input voltage.

L

3. Load Transient

A switching regulator typically takes several cycles to respond to the load current step. When a load step occurs, V to △I resistance of output capacitor. △I charge or discharge C signal used by the regulator to return V

immediately shifts by an amount equal

OUT

×ESR, where ESR is the effective series

LOAD

also begins to

LOAD

generating a feedback error

OUT

steady-state value. During the recovery time, V can be monitored for overshoot or ringing that would indicate a stability problem.

4. Output Voltage Setting

The output voltage of AUR9713 can be adjusted by a resistive divider according to the following formula:

VV

REFOUT

R

1

R

2

V

The resistive divider senses the fraction of the output voltage as shown in Figure 17.

VOUT

R1

R2

FB

AUR9713

GND

Figure 17. Setting the Output Voltage

10

R

1

+×=+×=

R

2

OUT

to its

OUT

)1(6.0)1(

+×=

Data Sheet

1.5MHz, 1A, STEP DOWN DC-DC CONVERTER AUR9713

Application Information (Continued)

5. Efficiency Considerations

The efficiency of switching regulator is equal to the output power divided by the input power times 100%. It is usually useful to analyze the individual losses to determine what is limiting efficiency and which change could produce the largest improvement. Efficiency can be expressed as:

Efficiency=100%-L1-L2-…..

Where L1, L2, etc. are the individual losses as a percentage of input power.

Although all dissipative elements in the regulator produce losses, two major sources usually account for most of the power losses: V

2

I

R losses. The VIN quiescent current loss dominates

the efficiency loss at very light load currents and the

2

I

R loss dominates the efficiency loss at medium to

heavy load currents.

5.1 The V

quiescent current loss comprises two

IN

parts: the DC bias current as given in the electrical characteristics and the internal MOSFET switch gate charge currents. The gate charge current results from switching the gate capacitance of the internal power MOSFET switches. Each cycle the gate is switched from high to low, then to high again, and the packet of charge, dQ moves from V resulting dQ/dt is the current out of V typically larger than the internal DC bias current. In

continuous mode,

QQfI +×=

Where Q

and QN are the gate charge of power

P

PMOSFET and NMOSFET switches. Both the DC bias current and gate charge losses are proportional to the V input voltages.

5.2 I

resistance, R

and this effect will be more serious at higher

IN

2

R losses are calculated from internal switch

and external inductor resistance RL.

SW

In continuous mode, the average output current flowing through the inductor is chopped between power PMOSFET switch and NMOSFET switch. Then, the series resistance looking into the LX pin is

quiescent current and

IN

to ground. The

IN

)(

NPGATE

that is

IN

a function of both PMOSFET R

and NMOSFET

DS(ON)

R

Therefore, to obtain the I R

resistance and the duty cycle (D):

DS(ON)

)(

DRDRR

−×

() ()

2

R losses, simply add RSW to

and multiply the result by the square of the

L

1

NONDSPONDSSW

average output current.

Other losses including C

and C

IN

ESR dissipative

OUT

losses and inductor core losses generally account for

less than 2 % of total additional loss.

6. Thermal Characteristics

In most applications, the part does not dissipate much heat due to its high efficiency. However, in some conditions when the part is operating in high ambient temperature with high R

resistance and high

DS(ON)

duty cycles, such as in LDO mode, the heat dissipated may exceed the maximum junction temperature. To avoid the part from exceeding maximum junction temperature, the user should do some thermal analysis. The maximum power dissipation depends on the layout of PCB, the thermal resistance of IC package, the rate of surrounding airflow and the temperature difference between junction and ambient.

7. PCB Layout Considerations

When laying out the printed circuit board, the following checklist should be used to optimize the performance of AUR9713.

1) The power traces, including the GND trace, the LX trace and the VIN trace should be kept direct, short and wide.

2) Put the input capacitor as close as possible to the

VIN and GND pins.

3) The FB pin should be connected directly to the

feedback resistor divider.

4) Keep the switching node, LX, away from the

sensitive FB pin and the node should be kept small area.

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Data Sheet

1.5MHz, 1A, STEP DOWN DC-DC CONVERTER AUR9713

Typical Application

Note 3:

When R2=300kΩ to 60 kΩ, the I component selection.

VV

REFOUT

+×= ;

V

OUT

3.3 450 100 13 2.2

R

1

)1(

R

2

=2µA to 10µA, and R1×C1 should be in the range between 3×10

R2

Figure 18. Typical Application Circuit of AUR9713

Table 1. Component Guide

(V)

R1 (kΩ)R2 (kΩ)

C1 (pF)

L1 (µH)

-6

and 6×10-6 for

2.5 320 100 18 2.2

1.8 200 100 30 2.2

1.2 100 100 56 2.2

1.0 66 100 91 2.2

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Data Sheet

1.5MHz, 1A, STEP DOWN DC-DC CONVERTER AUR9713

Mechanical Dimensions

TSOT-23-5 Unit: mm(inch)

5

°

4

X

7

°

GAUGE PLANE

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