PRODUCT SPECIFICATION

ILC7280

REV. 1.0.5 6/3/02

7

Application Information

These pins are connected internally through a galvanic

connection. For maximum power from each regulator, both

Enable/Shutdown

enables the regulator(s). These inputs are CMOS logic

compatible gates. If this feature is not required, connect

connected internally. To minimize the effect of imbalanced

should also be connected externally.

Input Capacitor

there is more than 10 inches of wire between the input and

the ac filter capacitor or if a battery is used as the input.

Reference Bypass Capacitor

tor’s A and B.

mended. Value higher than 1nF will lead to minimum

improvement of output noise, but it will substantially

faster start –up. If a slow or delayed start up time is desired,

times or instant-on applications will require smaller values

off of noise to response time should be considered.

Output Capacitor

GND to prevent oscillation and minimize the effect of load

transient currents. The minimum size of the output capaci-

Larger values of output capacitance will slightly slow the

regulator’s response during power up. The ILC7280 remains

stable even with ESR values as low as 10m

Ω.

If the system design calls for smaller load currents, lower

capacitance may be used. Below 10mA the capacitance may

be reduced to 0.33µF.

No-load Stability

The ILC7280 will remain stable and in regulation with no

load current. These are desirable performance features for

applications such as keep-alive modes in CMOS systems.

Split-Supply Operation

When using the ILC7280 in a system requiring that the load

be returned to the negative voltage source, the output(s) must

be diode clamped to inhibit significant voltage excursions

below ground. A simple external diode clamp to ground will

protect the device from damage.

Thermal Considerations

In order to minimize thermal resistance (

mounted on conventional FR4 PCB material should be

surrounded as much ground copper ground plane as

possible. In a worst case application with minimum trace

widths and no ground plane, the MSOP-8 package exhibits a

thermal resistance of 200 °C/W. The maximum allowable

power dissipation is calculated in the following examples.

Thermal Evaluation Examples

The maximum allowed package power dissipation is:

For an ambient temperature of 50°C

If the intent is to operate from a 4V power source with a

150mA load current from both outputs at a 50°C ambient

temperature, the expected power dissipation is found in the

following calculation:

In this example the total power dissipated is 300mW which

is below the 500mW maximum package consideration and

therefore safe to operate. It should be noted that it is not

always possible to operate both regulators at the maximum

output current.