1.5A Ultra Low Dropout Positive Adjustable or Fixed-mode Regulator

AP1186

Anachip Corp.

www.anachip.com.tw

Rev.1.1 Sep.7, 2004

4/8

Electrical Characteristics

Unless otherwise specified, these specifications apply over, Cin=1uF, Cout=10uF, and Tj=0 to 150

Vout = Vsense.

SYM.

Parameter

Test Condition

Min. Typ. Max. Unit

Thermal

Regulation

30ms Pulse

0.01 0.02 %W

Ripple Rejection

Vctrl =5V, Vin=5V, Io=1.5A, Vadj=0V, Tj=25,

Vripple=1Vpp at 120Hz

60

70

dB

Control Pin

Current

Vadj=0V for all conditions below.

Vctrl=2.75V, Vin=2.05V, Io=1.5A

6

25

mA

Iadj Adjust Pin Current Vctrl=2.75V, Vin=2.05,Vadj=0

50

150

µA

Thermal

Resistance

Junction-to-Case

TO-263: Control Circuitry/Power Transistor

TO-220: Control Circuitry/Power Transistor

2.5

2.5

NOTE:

AP1186-ADJ incorporates an internal thermal shutdown that protects the device when the junction temperature exceeds the allowable

maximum junction temperature.

Package

Max Pd.

TO-263/TO-220 2.4W~4.4W

With heat sink or amount of copper board needed.

Functional Descriptions

Introduction

The AP1186 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 AP1186 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 AP1186-ADJ 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 AP1186 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 AP1186-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: