AMS2905-2.5 - Advanced Monolithic Systems

Advanced Monolithic Systems, Inc. 6680B Sierra Lane, Dublin, CA 94568 Phone (925) 556-9090 Fax (925) 556-9140

Advanced AMS2905

Monolithic 500mA LOW DROPOUT VOLTAGE REGULATOR

Systems

FEATURES APPLICATIONS

•• Three Terminal Adjustable or Fixed Voltages* •• High Efficiency Linear Regulators

1.5V, 2.5V, 2.85V, 3.3V and 5.0V •• Post Regulators for Switching Supplies

•• Output Current of 500mA •• 5V to 3.3V Linear Regulator

•• Operates Down to 1V Dropout •• Battery Chargers

•• Line Regulation: 0.2% Max. •• Sound Cards

•• Load Regulation: 0.4% Max. •• Power Management for Notebook

•• TO-252, SOT-223 and SOT-89 packages •• Battery Powered Instrumentation

GENERAL DESCRIPTION

The

The AMS2905 series of adjustable and fixed voltage regulators are designed to provide 500mA output current and to operate

down to 1V input-to-output differential. The dropout voltage of the device is guaranteed maximum 1.3V at maximum output

current, decreasing at lower load currents.

On-chip trimming adjusts the reference voltage to 1%. Current limit is also trimmed, minimizing the stress under overload

conditions on both the regulator and power source circuitry.

The AMS2905 devices are pin compatible with other three-terminal regulators and are offered in the low profile surface

mount TO-252(DPAK), SOT-223 and SOT-89 packages.

ORDERING INFORMATION:

PACKAGE TYPE OPERATING JUNCTION

SOT-89 TO-252 SOT-223 TEMPERATURE

RANGE

AMS2905CL AMS2905CD AMS2905 0 to 125° C

AMS2905CL-1.5 AMS2905CD-1.5 AMS2905-1.5 0 to 125° C

AMS2905CL-2.5 AMS2905CD-2.5 AMS2905-2.5 0 to 125° C

AMS2905CL-2.85 AMS2905CD-2.85 AMS2905-2.85 0 to 125° C

AMS2905CL-3.3 AMS2905CD-3.3 AMS2905-3.3 0 to 125° C

AMS2905CL-5.0 AMS2905CD-5.0 AMS2905-5.0 0 to 125° C

*For additional available fixed voltages contact factory.

PIN CONNECTIONS

FIXED VERSION ADJUSTABLE VERSION

1- VIN

2- Ground

3- VOUT

1- VIN

2- Adjust

3- VOUT

SOT-89 Top View

321

SOT-223 Top View

123

TO-252 Front View

Advanced Monolithic Systems, Inc. 6680B Sierra Lane, Dublin, CA 94568 Phone (925) 556-9090 Fax (925) 556-9140

AMS2905

ABSOLUTE MAXIMUM RATINGS (Note 1)

Power Dissipation Internally limited Thermal Resistance

Input Voltage 15V SOT-89 package ϕ

= 110°C/W

Operating

Junction Temperature Range

TO-252 package ϕ

= 80°C/W

Control Section 0°C to 125°C SOT-223 package ϕ

= 90°C/W*

Power Transistor 0°C to 150°C

Storage temperature - 65°C to +150°C

Soldering information

Lead Temperature (10 sec) 300°C

* With package soldering to copper area over backside

ground plane or internal power plane ϕ JA can vary from

46°C/W to >90°C/W depending on mounting technique and

the size of the copper area.

ELECTRICAL CHARACTERISTICS

Electrical Characteristics at IOUT = 0 mA, and TJ = +25°C unless otherwise specified.

Parameter Device Conditions Min Typ Max Units

Reference Voltage

(Note 2) AMS2905 IOUT = 10 mA

10mA ≤ IOUT ≤ 500mA, 1.5V≤ (VIN - VOUT) ≤ 12V 1.238

1.225 1.250

1.250 1.262

1.270 V

Output Voltage

(Note 2) AMS2905-1.5 0 ≤ IOUT ≤ 500mA , 4.35V≤ VIN ≤ 12V 1.485

1.476 1.500

1.500 1.515

1.524 V

AMS2905-2.5 0 ≤ IOUT ≤ 500mA , 4.35V≤ VIN ≤ 12V 2.475

2.460 2.500

2.500 2.525

2.560 V

AMS2905-2.85 0 ≤ IOUT ≤ 500mA , 4.35V≤ VIN ≤ 12V 2.82

2.79 2.850

2.850 2.88

2.91 V

AMS2905-3.3 0 ≤ IOUT ≤ 500mA , 4.75V ≤ VIN ≤ 12V 3.267

3.235 3.300

3.300 3.333

3.365 V

AMS2905-5.0 0 ≤ IOUT ≤ 500mA , 6.5V ≤ VIN ≤ 12V 4.950

4.900 5.000

5.000 5.050

5.100 V

Line Regulation AMS2905 ILOAD = 10 mA , 1.5V≤ (VIN - VOUT) ≤ 12V 0.015

0.035 0.2

0.2 %

AMS2905-1.5 3.0V≤ VIN ≤ 12V 0.3

0.6 5

6mV

AMS2905-2.5 4.0V≤ VIN ≤ 12V 0.3

0.6 6

6mV

AMS2905-2.85 4.35V≤ VIN ≤ 12V 0.3

0.6 6

6mV

AMS2905-3.3 4.75V≤ VIN ≤ 12V 0.5

1.0 10

10 mV

AMS2905-5.0 6.5V≤ VIN ≤ 12V 0.5

1.0 10

10 mV

Load Regulation

(Notes 2, 3)

AMS2905 (VIN - VOUT) =3V, 10mA ≤ IOUT ≤ 500mA 0.1

0.2 0.3

0.4 %

AMS2905-1.5 VIN = 5V, 0 ≤ IOUT ≤ 500mA 3

610

20 mV

AMS2905-2.5 VIN = 5V, 0 ≤ IOUT ≤ 500mA 3

612

20 mV

AMS2905-2.85 VIN = 5V, 0 ≤ IOUT ≤ 500mA 3

612

20 mV

AMS2905-3.3 VIN = 5V, 0 ≤ IOUT ≤ 500mA 3

715

25 mV

AMS2905-5.0 VIN = 8V, 0 ≤ IOUT ≤ 500mA 5

10 20

35 mV

Advanced Monolithic Systems, Inc. 6680B Sierra Lane, Dublin, CA 94568 Phone (925) 556-9090 Fax (925) 556-9140

AMS2905

ELECTRICAL CHARACTERISTICS

Electrical Characteristics at IOUT = 0 mA, and TJ = +25°C unless otherwise specified.

Parameter Device Conditions Min Typ Max Units

Dropout Voltage

(VIN - VOUT)AMS2905-1.5/-2.5/-2.85/

-3.3/-5.0 ∆VOUT , ∆VREF = 1%, IOUT = 500mA (Note 4) 1.1 1.3 V

Current Limit AMS2905-1.5/-2.5/-2.85/

-3.3/-5.0

(VIN - VOUT) = 5V 1,000 mA

Minimum Load

Current AMS2905 (VIN - VOUT) = 12V (Note 5) 5 10 mA

Quiescent Current AMS2905-1.5/-2.5/-2.85/

-3.3/-5.0 VIN ≤ 12V 5 10 mA

Ripple Rejection AMS2905 f =120Hz , COUT = 25µF Tantalum, IOUT = 500mA,

(VIN-VOUT ) = 3V, CADJ =25µF60 75 dB

AMS2905-1.5 f =120Hz , COUT = 25µF Tantalum, IOUT = 500mA,

VIN = 6V 60 72 dB

AMS2905-2.5 f =120Hz , COUT = 25µF Tantalum, IOUT = 500mA,

VIN = 6V 60 72 dB

AMS2905-2.85 f =120Hz , COUT = 25µF Tantalum, IOUT = 500mA,

VIN = 6V 60 72 dB

AMS2905-3.3 f =120Hz , COUT = 25µF Tantalum, IOUT = 500mA

VIN = 6.3V 60 72 dB

AMS2905-5 f =120Hz , COUT = 25µF Tantalum, IOUT = 500mA

VIN = 8V 60 68 dB

Thermal Regulation AMS2905 TA = 25°C, 30ms pulse 0.008 0.04 %W

Adjust Pin Current AMS2905 10mA ≤ IOUT ≤ 500mA , 1.5V≤ (VIN - VOUT) ≤ 12V 55 120 µA

µA

Adjust Pin Current

Change AMS2905 10mA ≤ IOUT ≤ 500mA , 1.5V≤ (VIN - VOUT) ≤ 12V 0.2 5µA

Temperature Stability 0.5 %

Long Term Stability TA =125°C, 1000Hrs 0.3 1%

RMS Output Noise

(% of VOUT ) TA = 25°C , 10Hz ≤ f ≤ 10kHz 0.003 %

Thermal Resistance

Junction-to-Case 15 °C/W

Parameters identified with boldface type apply over the full operating temperature range.

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. For guaranteed specifications and test conditions, see the

Electrical Characteristics. The guaranteed specifications apply only for the test conditions listed.

Note 2: Line and Load regulation are guaranteed up to the maximum power dissipation of 1.2W for SOT-223 package and 0.9W for SOT-89 package. Power

dissipation is determined by the input/output differential and the output current. Guaranteed maximum power dissipation will not be available over the full

input/output range.

Note 3: See thermal regulation specifications for changes in output voltage due to heating effects. Line and load regulation are measured at a constant junction

temperature by low duty cycle pulse testing. Load regulation is measured at the output lead ~1/8” from the package.

Note 4: Dropout voltage is specified over the full output current range of the device.

Note 5: Minimum load current is defined as the minimum output current required to maintain regulation. When 1.5V ≤ (VIN - VOUT) ≤ 12V the device is

guaranteed to regulate if the output current is greater than 10mA.

Advanced Monolithic Systems, Inc. 6680B Sierra Lane, Dublin, CA 94568 Phone (925) 556-9090 Fax (925) 556-9140

AMS2905

APPLICATION HINTS

The AMS2905 series of adjustable and fixed regulators are easy

to use and are protected against short circuit and thermal

overloads. Thermal protection circuitry will shut-down the

regulator should the junction temperature exceed 165°C at the

sense point.

Pin compatible with older three terminal adjustable regulators,

these devices offer the advantage of a lower dropout voltage,

more precise reference tolerance and improved reference stability

with temperature.

Stability

The circuit design used in the AMS2905 series requires the use of

an output capacitor as part of the device frequency compensation.

The addition of 150µF aluminum electrolytic or a 22µF solid

tantalum on the output will ensure stability for all operating

conditions.

When the adjustment terminal is bypassed with a capacitor to

improve the ripple rejection, the requirement for an output

capacitor increases. The value of 22µF tantalum or 150µF

aluminum covers all cases of bypassing the adjustment terminal.

Without bypassing the adjustment terminal smaller capacitors can

be used with equally good results.

To ensure good transient response with heavy load current

changes capacitor values on the order of 100µF are used in the

output of many regulators. To further improve stability and

transient response of these devices larger values of output

capacitor can be used.

Protection Diodes

Unlike older regulators, the AMS2905 family does not need any

protection diodes between the adjustment pin and the output and

from the output to the input to prevent over-stressing the die.

Internal resistors are limiting the internal current paths on the

AMS2905 adjustment pin, therefore even with capacitors on the

adjustment pin no protection diode is needed to ensure device

safety under short-circuit conditions.

Diodes between the input and output are not usually needed.

Microsecond surge currents of 50A to 100A can be handled by the

internal diode between the input and output pins of the device. In

normal operations it is difficult to get those values of surge

currents even with the use of large output capacitances. If high

value output capacitors are used, such as 1000µF to 5000µF and

the input pin is instantaneously shorted to ground, damage can

occur. A diode from output to input is recommended, when a

crowbar circuit at the input of the AMS2905 is used (Figure 1).

AMS2905

IN OUT

ADJ +COUT

150µF

VOUT

CADJ

10µF

VIN

Figure 1.

Output Voltage

The AMS2905 series develops a 1.25V reference voltage

between the output and the adjust terminal. Placing a resistor

between these two terminals causes a constant current to flow

through R1 and down through R2 to set the overall output

voltage. This current is normally the specified minimum load

current of 10mA. Because I

ADJ

is very small and constant it

represents a small error and it can usually be ignored.

AMS2905

IN OUT

ADJ R1

VOUT

VREF

VIN

IADJ

50µA

VOUT = VREF (1+ R2/R1)+IADJR2

Figure 2. Basic Adjustable Regulator

Load Regulation

True remote load sensing it is not possible to provide, because

the AMS2905 is a three terminal device. The resistance of the

wire connecting the regulator to the load will limit the load

regulation. The data sheet specification for load regulation is

measured at the bottom of the package. Negative side sensing is a

true Kelvin connection, with the bottom of the output divider

returned to the negative side of the load.

The best load regulation is obtained when the top of the resistor

divider R1 is connected directly to the case not to the load. If R1

were connected to the load, the effective resistance between the

regulator and the load would be:

RP x ( R2+R1 ) , RP = Parasitic Line Resistance

Advanced Monolithic Systems, Inc. 6680B Sierra Lane, Dublin, CA 94568 Phone (925) 556-9090 Fax (925) 556-9140

AMS2905

APPLICATION HINTS

Connected as shown , RP is not multiplied by the divider ratio

AMS2905

IN OUT

ADJ

R1*

R2*

VIN

PARASITIC

LINE RESISTANCE

*CONNECT R1 TO CASE

CONNECT R2 TO LOAD

Figure 3. Connections for Best Load Regulation

In the case of fixed voltage devices the top of R1 is connected

Kelvin internally, and the ground pin can be used for negative

side sensing.

Thermal Considerations

The AMS2905 series have internal power and thermal limiting

circuitry designed to protect the device under overload conditions.

However maximum junction temperature ratings of 125°C should

not be exceeded under continuous normal load conditions.

Careful consideration must be given to all sources of thermal

resistance from junction to ambient. For the surface mount

package SOT-223 additional heat sources mounted near the

device must be considered. The heat dissipation capability of the

PC board and its copper traces is used as a heat sink for the

device. The thermal resistance from the junction to the tab for the

AMS2905 is 15°C/W. Thermal resistance from tab to ambient

can be as low as 30°C/W.

The total thermal resistance from junction to ambient can be as

low as 45°C/W. This requires a reasonable sized PC board with

at least on layer of copper to spread the heat across the board and

couple it into the surrounding air.

Experiments have shown that the heat spreading copper layer

does not need to be electrically connected to the tab of the device.

The PC material can be very effective at transmitting heat

between the pad area, attached to the pad of the device, and a

ground plane layer either inside or on the opposite side of the

board. Although the actual thermal resistance of the PC material

is high, the Length/Area ratio of the thermal resistance between

layers is small. The data in Table 1, was taken using 1/16” FR-4

board with 1 oz. copper foil, and it can be used as a rough

guideline for estimating thermal resistance.

For each application the thermal resistance will be affected by

thermal interactions with other components on the board. To

determine the actual value some experimentation will be

necessary.

The power dissipation of the AMS2905 is equal to:

PD = ( VIN - VOUT )( IOUT )

Maximum junction temperature will be equal to:

TJ = TA(MAX) + PD(Thermal Resistance (junction-to-ambient))

Maximum junction temperature must not exceed 125°C.

Ripple Rejection

The ripple rejection values are measured with the adjustment pin

bypassed. The impedance of the adjust pin capacitor at the ripple

frequency should be less than the value of R1 (normally 100Ω to

200Ω) for a proper bypassing and ripple rejection approaching

the values shown. The size of the required adjust pin capacitor is

a function of the input ripple frequency. If R1=100Ω at 120Hz

the adjust pin capacitor should be >13µF. At 10kHz only 0.16µF

is needed.

The ripple rejection will be a function of output voltage, in

circuits without an adjust pin bypass capacitor. The output ripple

will increase directly as a ratio of the output voltage to the

reference voltage (VOUT / VREF).

Table 1.

COPPER AREA THERMAL RESISTANCE

TOP SIDE* BACK SIDE BOARD AREA (JUNCTION-TO-AMBIENT)

2500 Sq. mm 2500 Sq. mm 2500 Sq. mm 45°C/W

1000 Sq. mm 2500 Sq. mm 2500 Sq. mm 45°C/W

225 Sq. mm 2500 Sq. mm 2500 Sq. mm 53°C/W

100 Sq. mm 2500 Sq. mm 2500 Sq. mm 59°C/W

1000 Sq. mm 1000 Sq. mm 1000 Sq. mm 52°C/W

1000 Sq. mm 01000 Sq. mm 55°C/W

* Tab of device attached to topside copper.

Advanced Monolithic Systems, Inc. 6680B Sierra Lane, Dublin, CA 94568 Phone (925) 556-9090 Fax (925) 556-9140

AMS2905

TYPICAL PERFORMANCE CHARACTERISTICS

Minimum Operating Current

(Adjustable Device) Short-Circuit Current

Load Regulation Ripple Rejection vs. Current

Adjust Pin CurrentTemperature Stability

0 5 10 15 20

INPUT/OUTPUT DIFFERENTIAL (V)

0 5 10 15

MINIMUM OPERATING CURRENT (mA)

INPUT/OUTPUT DIFFERENTIAL

0.25

0.50

0.75

1.00

1.25

SHORT CIRCUIT CURRENT (A)

-50 -25 0 25 50 75 100 125

-0.20

-0.15

-0.10

-0.05

0.05

0.10

TEMPERATURE (°C)

OUTPUT VOLTAGE DEVIATION (%)

00.15 0.3 0.45 0.6

100

OUTPUT CURRENT (A)

RIPPLE REJECTION (dB)

-50 -25 0 25 50 75 100 125 150

-2.0

-1.0

1.0

2.0

TEMPERATURE (°C)

OUTPUT VOLTAGE CHANGE (%)

TEMPERATURE (°C)

-50 -25 0 25 50 75 100 125 150

100

ADJUST PIN CURRENT (µA)

TJ = 125°C

TJ = 25°C

fRIPPLE = 120Hz

fRIPPLE = 20Hz

VRIPPLE≤3Vp-p

VRIPPLE≤0.5Vp-p

∆ ILOAD = 500mA

VOUT = 5V

CADJ = 25µF

COUT = 25µF

TJ = 125°C

TJ = 25°C

Advanced Monolithic Systems, Inc. 6680B Sierra Lane, Dublin, CA 94568 Phone (925) 556-9090 Fax (925) 556-9140

AMS2905

PACKAGE DIMENSIONS inches (millimeters) unless otherwise noted.

TO-252 PLASTIC PACKAGE (D)

3 LEAD SOT-223 PLASTIC PACKAGE

0.030

(0.762)

TYP

0.085-0.095

(2.159-2.413) 0.030-0.034

(0.762-0.863)

0.024±0.002

(0.610±0.0508)

0.018-0.022

(0.451-0.558)

0.038

(0.965)

TYP

D (D3) AMS DRW# 042891

0.038-0.042

(0.965-1.066)

0.038-0.042

(0.965-1.066)

0.235-0.245

(5.969-6.223)

0.088-0.092

(2.235-2.336)

0.099-0.103

(2.514-2.615)

0.175-0.180

(4.191-4.445)

0.023-0.027

(0.584-0.685)

0.020-0.030

(0.508-0.762)

0.258-0.262

(6.553-6.654)

0.033-0.037

(0.838-0.939)

0.020-0.030

(0.508-0.762)

0.208-0.212

(5.283-5.384)

0.025

(0.635)

TYP

0.057-0.067

(0.144-0.170)

DIA

45.0° 7.0°

0.130-0.146

(3.30-3.71)

0.248-0.264

(6.30-6.71)

0.116-0.124

(2.95-3.15)

0.264-0.287

(6.71-7.29)

0.090

(2.29)

NOM

0.071

(1.80)

MAX

0.033-0.041

(0.84-1.04)

0.025-0.033

(0.64-0.84)

0.181

(4.60)

NOM

0.012

(0.31)

MIN

0.025-0.033

(0.64-0.84)

10°

MAX

10°-16°

0.010-0.014

(0.25-0.36)

(SOT-223 ) AMS DRW# 042292

Advanced Monolithic Systems, Inc. 6680B Sierra Lane, Dublin, CA 94568 Phone (925) 556-9090 Fax (925) 556-9140

AMS2905

PACKAGE DIMENSIONS inches (millimeters) unless otherwise noted (Continued).

SOT-89 PLASTIC PACKAGE (L)

0.090-0.102

(2.29-2.60)

0.173-0.181

(4.40-4.60)

0.064-0.072

(1.62-1.83)

0.155-0.167

(3.94-4.25)

0.059

(1.50)

BSC

0.035-0.047

(0.89-1.20)

L (SOT-89 ) AMS DRW# 042392

0.118

(3.00)

BSC

0.014-0.019

(0.36-0.48)

0.017-0.022

(0.44-0.56)

0.084-0.090

(2.13-2.29)

0.055-0.063

(1.40-1.60) 0.014-0.017

(0.35-0.44)