ACE1085G

3A Low Dropout Linear Regulator

VER 1.4

4

Thermal Resistance

Junction

–to-Ambient

(No heat sink ;No air

flow)

98

℃/W

Thermal Resistance

Junction-to-Case

Control Circuitry / Power Transistor

15

℃/W

Note 1: 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 =1/18” from the package.

Note 2: Line and load regulation are guaranteed up to the maximum power dissipation of 15W. Power dissipation is determined by

the difference in input and output and the output current. Guaranteed maximum power dissipation will not be available

over the full input/output range.

Functional Description

Introduction

The ACE1085G adjustable or fixed-mode Low Dropout (LDO) regulator is a 3 terminal device which can

easily be programmed by internal mask change to any voltage within the range of 1.25 to Vin-1.4V. The

ACE1085G only needs 1.4V differential between Vin and Vout to maintain output regulation, in addition,

the output voltage tolerances are also extremely tight and they include the transient response as port of the

specification. For example, Intel VRE specification calls for a total of ±100mV including initial tolerance,

load regulation and 0 to 3A load step. The ACE1085G 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 output capacitors.

Load Regulation

Since the ACE1085G is only a 3 terminal device, it is not possible to provide true remote sensing of the

output voltage at the load. But it can supply good load regulation by internal feedback bypass the external

loss such as adjustable mode.

Stability

The ACE1085G requires the use of an output capacitor as part of the frequency compensation in order to

make the regulator stable .For most applications a minimum of 10uF aluminum electrolytic capacitor

insures both stability and good transient response.

Thermal Design

The ACE1085G incorporates an internal shutdown that protects the device when the junction

temperature exceeds the maximum allowable junction temperatures. Although this device can operate

with junction temperatures in the range of 150℃, it is recommended that the selected heat sink be chosen

such that during maximum continuous load operation the junction temperature is kept below the

temperature.

Layout Consideration

The output capacitors must be located as close to the Vout terminal of the device as possible .It is

recommended to use a section of a layer of the PC board as a plane to connect the Vout pin to the output

capacitors to prevent any high frequency oscillation that may result due to excessive trace inductance.