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AP1184T5

4A ULTRA LOW DROPOUT POSITIVE ADJUSTABLE OR FIXED-MODE REGULATOR

Diodes Incorporated. 

AP1184

4A ULTRA LOW DROPOUT POSITIVE ADJUSTABLE OR

FIXED-MODE REGULATOR

Electrical Characteristics ( Continued )

Unless otherwise specified, these specifications apply over, Cin = 1uF, Cout = 10uF, and Tj = 0 to 150oC. Typical value refer to TA = 25oC.

Vout = Vsense.

Sym. Parameter

Test Condition

Min. Typ. Max. Unit

I adj

Adjust Pin Current

Vctrl = 2.75V, Vin = 2.05,Vadjj = 0

50 150 µA

θJA Thermal Resistance

Junction-to-Ambient

θJC Thermal Resistance

Junction-to-Case

TO263-3L: Control Circuitry/Power Transistor (Note 4)

TO220-3L: Control Circuitry/Power Transistor (Note 4)

SOP-8L: Control Circuitry/Power Transistor (Note 5)

TO263-3L: Control Circuitry/Power Transistor (Note 4)

TO220-3L: Control Circuitry/Power Transistor (Note 4)

SOP-8L: Control Circuitry/Power Transistor (Note 5)

23

OC/W

15

OC/W

118

OC/W

3.5

OC/W

2.5

OC/W

5.4

OC/W

Note:

3. AP1184-ADJ incorporates an internal thermal shutdown that protects the device when the junction temperature exceeds the allowable maximum

junction temperature.

4. Test conditions for TO263-3L and TO220-3L: with copper area of approximately 3in2, 1oz.

5. Test conditions for SOP-8L: mounted on 2oz. copper, minimum recommended pad layout, FR-4 PCB.

Package

Max Pd.

TO263-3L/TO220-3L 2.4W~4.4W

SOP-8L

1W~2W

Remarks

With heat sink or amount of copper board needed.

With heat sink or amount of copper board needed.

Functional Descriptions

Introduction

The AP1184 regulator is a 5 terminal device designed specifically to provide extremely low dropout voltages comparable to the

PNP type without the disadvantage of the extra power dissipation due to the base current associated with PNP regulators. This is done

by bringing out the control pin of the regulator that provides the base current to the power NPN and connecting it to a voltage that is

greater than the voltage present at the Vin pin. This flexibility makes the AP1184 ideal for applications where dual inputs are available

such as a computer motherboard with an ATX style power supply that provides 5V and 3.3V to the board. One such application is the

new graphic chip sets that require anywhere from 2.4V to 2.7V supply. The AP1184 can easily be programmed with the addition of two

external resistors to any voltages within the range of 1.25V to 15.5V. Another major requirement of these graphic chips is the need to

switch the load current from zero to several amps in tens of nanoseconds at the processor pins, which translates to an approximately 300

to 500ns of current step at the regulator. In addition, the output voltage tolerances are also extremely tight and they include the transient

response as part of the specification.

The AP1184 is specifically designed to meet the fast current transient needs as well as providing an accurate initial voltage,

reducing the overall system cost with the need for fewer number of output capacitors. Another feature of the device is its true remote

sensing capability that allows accurate voltage setting at the load rather than at the device.

Output Voltage Setting

The AP1184-ADJ can be programmed to any voltages in the range of 1.25V to 15.5V with the addition of R1 and R2 external

resistors according to the following formula:

AP1184 Rev. 1

5 of 12

www.diodes.com

MARCH 2007

© Diodes Incorporated

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