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AX6608B-V1.4

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600mA High PSRR, Low Noise LDO Regulator

GENERAL DESCRIPTION The AX6608B is a low dropout, high PSRR, low noise linear regulator with very low quiescent. It can supply 600mA output current with low dropout voltage and very low output voltage. The Device includes pass element, error amplifier, band-gap, current-limit and thermal shutdown circuitry. The characteristics of low dropout voltage and less quiescent current make it good for some critical current application, for example, some battery powered devices. The typical quiescent current is approximately 30μA. In the shutdown mode, the maximum supply current is less than 1uA. Due to internal flexible design, result in extensively fixed output voltage versions is 1.0V/1.2V/1.5V/1.8V/2.5V/2.8V/3.0V/3.3V. Built-in current-limit and thermal-shutdown functions prevent any fault condition from IC damage.

FEATURES

- Input voltage range : 2.8V~5.5V - Guaranteed 600mA output current - Low quiescent current is 30μA (typ.)

- Maximum supply current in shutdown mode <1uA

- Fixed Output voltage is 1.0V/1.2V/1.5V/1.8V/2.5V/2.8V/3.0V/3.3V . - High PSRR=-60dB@1KHz

- Low-ESR Ceramic Capacitor for output stability - Fast transient response

- Current limit and thermal shutdown protection

Available in the 5-Pin Pb-Free SOT23 and SC70 Packages BLOCK DIAGRAM

VIN

VOUT

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PIN ASSIGNMENT

The packages of AX6608B are SOT23-5L and SC70-5L; the pin assignment is given by:

Appendix

Identification Code Part Number SOT23 SC70

AX6608B-1.0V

A A AX6608B-1.5V C C AX6608B-1.8V D D AX6608B-2.5V F F AX6608B-2.8V G G AX6608B-3.0V H H AX6608B-3.3V

I I

Name Description

VIN

Voltage input. The input capacitor in the range of 1uF to 10uF is sufficient.

GND Ground

EN Enable pin (Active High) BP Reference Noise Bypass (The Bypass

capacitor ≧1nF

(Top View)SOT23-5L/SC70-5L 3

541VIN GND EN BP VOUT

VOUT Output Voltage, The AX6608B is stable with an output capacitor 1uF for

greater.

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Date Code

1.Year ：The under-line see the IC top marking XX ：2004, 2008, 2012… XX ：2003, 2007, 2011… XX ：2002, 2006, 2010… XX ：2001, 2005, 2009…

2.Week ：See the English word

XX ："A~Z" showed on 1rd position --> week 1 ~ week 26, XX ："A~Z" showed on 2th position --> week 27 ~ week 52. 3. ID Code (internal)：See the number word XX ："1~9" showed on 1rd or 2rd position

ABSOLUTE MAXIMUM RATINGS (at T A =25 °C)

Characteristics

Symbol Rating Unit V IN Pin Voltage V IN GND - 0.3 to GND + 6 V Output Voltage V OUT GND - 0.3 to V IN + 0.3 V Enable Voltage V EN GND - 0.3 to GND + 6 V Power Dissipation

PD 250 mW Storage Temperature Range T ST -40 to +150 °C Operating Temperature Range T OP -40 to +85 °C Junction Temperature

T J -40 to +125 °C Thermal Resistance from Junction to case θJC SOT23=180,SC70=230 °C/W Thermal Resistance from Junction to ambient θJA SOT23=250,SC70=280 °C/W

Note: θJA is measured with the PCB copper area of approximately 1 in 2(Multi-layer). That need connect to V IN pin.

ELECTRICAL CHARACTERISTICS

(V IN =V OUT +1V or V IN =2.8V whichever is greater, C IN =C OUT =1uF, T A =25 °C, unless otherwise noted)

Characteristics Symbol Conditions Min Typ Max Units Input Voltage V IN (Note1) 2.8 - 5.5 V Output Voltage Accuracy ΔV OUT I OUT =1mA -2 - +2 % Quiescent Current I Q I OUT =0mA - 30 60 μA

1.0V ≦V OUT ≦

2.0V - 1000 1600

2.0V ＜V OUT ≦2.8V - 350 600

Dropout Voltage (Note2) V DROP I OUT =600mA 2.8V ＜V OUT ≦3.3V - 250 500

mV Current Limit I LIMIT R LOAD =1? 600 650 - mA

Line Regulation ΔV LINE I OUT =1mA,

V IN =V OUT +1.5V to 5V

- 1 5 mV

Load Regulation (Note 3) ΔV LOAD I OUT =0m~600mA - 50 100 mV

F=1KHz - -60 -

Ripple Rejection PSRR C OUT =1uF,I OUT =1mA F =10K - -40 -

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Characteristics

Symbol Conditions Min Typ Max Units V ENH - 1.4 - -

Enable Input Threshold V ENL - - - 0.4

Enable Pin Current I EH V EN =V IN - - 0.1 μA

Shutdown Current

I SD V IN =3.6V, V EN =0V - - 1 μA

Temperature Coefficient TC I OUT =1mA, V IN =5V - 50 - ppm/

°C Temperature Shutdown TS - - 160 - °C Temperature Shutdown

Hysterisis

TSH - - 25 - °C

Note1. Minimum V IN voltage is defined by output adds a dropout voltage.

Note2. The dropout voltage is defined as V IN -V OUT , which is measured when V OUT drop about 100mV.

Note3. Regulation is measured at constant junction temperature by using pulsed testing with a low ON time.

APPLICATION CIRCUIT

FUNCTION DESCRIPTIONS

A minimum of 1uF capacitor must be connected from V OUT to ground to insure stability. Typically a large storage capacitor is connected from V IN to ground to ensure that the input voltage does not sag below the minimum dropout voltage during the load transient response. This pin must always be dropout voltage higher than V OUT in order for the device to regulate properly.

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APPLICATION INFORMATION

Like any low-dropout regulator, the AX6608B requires input and output decoupling capacitors. The device is specifically designed for portable applications requiring minimum board space and smallest components. These capacitors must be correctly selected for good performance (see Capacitor Characteristics Section). Please note that linear regulators with a low dropout voltage have high internal loop gains which require care in guarding against oscillation caused by insufficient decoupling capacitance.

Capacitor Selection

Normally, use a 1μF capacitor on the input and a 1μF capacitor on the output of the AX6608B. Larger input capacitor values and lower ESR provide better supply-noise rejection and transient response. A large value output capacitor may be necessary if large, fast transients are anticipated and the device is located several inches from the power source. The capacitors is recommended to use 1uF X5R or X7R dielectric ceramic capacitors with 30m ? to 50m ? ESR range between device outputs to ground for transient stability.

Input-Output (Dropout) Voltage

A regulator's minimum input-to-output voltage differential (dropout voltage) determines the lowest usable supply voltage. In battery-powered systems, this determines the useful end-of-life battery voltage. Because the device uses a PMOS, its dropout voltage is a function of drain-to source on-resistance, R DS (ON), multiplied by the load current:

V DROPOUT = V IN -V OUT = R DS (ON) x I OUT

Current Limit and Thermal Shutdown Protection

In order to prevent overloading or thermal condition from damaging the device, AX6608B regulator has internal thermal and current limiting functions designed to protect the device. It will rapidly shut off PMOS pass element during overloading or over temperature condition.

Thermal Considerations

The AX6608B series can deliver a current of up to 300mA over the full operating junction temperature range. However, the maximum output current must be dated at higher ambient temperature to ensure the junction temperature does not exceed 125°C. With all possible conditions, the junction temperature must be within the range specified under operating conditions. Power dissipation can be calculated based on the output current and the voltage drop across regulator.

PD = (V IN - V OUT ) I OUT

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The final operating junction temperature for any set of conditions can be estimated by the following thermal equation:

PD (MAX) = (T J (MAX) - T A ) / θJA

Where T J (MAX) is the maximum junction temperature of the die (125°C ) and T A is the maximum ambient temperature. The junction to ambient thermal resistance (θJA ) for SOT-23-5 package at recommended minimum footprint is 250°C/W .

PCB Layout

An input capacitance of ?1μF is required between the AX6608B input pin and ground (the amount of the capacitance may be increased without limit), this capacitor must be located a distance of not more than 1cm from the input and return to a clean analog ground. Input capacitor can filter out the input voltage spike caused by the surge current due to the inductive effect of the package pin and the printed circuit board’s routing wire. Otherwise, the actual voltage at the V IN pin may exceed the absolute maximum rating. The output capacitor also must be located a distance of not more than 1cm from output to a clean analog ground. Because it can filter out the output spike caused by the surge current due to the inductive effect of the package pin and the printed circuit board’s routing wire.

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TYPICAL CHARACTERISTICS

(Frequency) (Hz)

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PACKAGE OUTLINES (1) SOT23-5L

DETAL A

Dimensions in Millimeters Dimensions in Inches Symbol

Min. Nom. Max. Min. Nom. Max.

A 1.05 - 1.45 0.041 - 0.057 A1 0.05 - 0.15 0.002 - 0.006 A2 0.90 1.10 1.30 0.035 0.043 0.051 b 0.30 - 0.50 0.012 - 0.020 C 0.08 - 0.22 0.003 - 0.009 D 2.70 2.90 3.10 0.106 0.114 0.122 E1 1.40 1.60 1.80 0.055 0.063 0.071 E 2.60 2.80 3.00 0.102 0.110 0.118 L 0.30 - 0.60 0.012 - 0.024 L1 0.50 0.60 0.70 0.020 0.024 0.028 e1 1.80 1.90 2.00 0.071 0.075 0.079 e 0.85 1.00 1.15 0.033 0.039 0.045 θ 0o 4o 8o 0o 4o 8o θ1 5o 10o 15o 5o 10o 15o θ2 5o 10o 15o 5o 10o 15o

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(2) SC70-5L

Dimensions in Millimeters Dimensions in Inches Symbol

Min. Nom. Max. Min. Nom. Max.

A 0.80 - 1.10 0.031 - 0.043 A1 0.00 - 0.10 0.000 - 0.004 A2 0.70 0.90 1.00 0.028 0.035 0.039 b 0.15 - 0.30 0.006 - 0.012 C 0.08 - 0.22 0.003 - 0.009 D 1.80 2.00 2.20 0.071 0.079 0.087 E 1.95 2.10 2.25 0.077 0.083 0.089 E1 1.15 1.25 1.35 0.045 0.049 0.053 e - 0.65 - - 0.026 - e1 - 1.30 - - 0.051 - L 0.26 0.36 0.46 0.010 0.014 0.018 L2 - 0.15 - - 0.006 - y - - 0.10 - - 0.004 θ 0o 4o 8o 0o 4o 8o θ1 4o - 12o 4o - 12o