TS1582CM5 查看數據表（PDF） - TSC Corporation

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TS1582CM5

3A Dual Input LDO

TSC Corporation 

TS1582

3A Dual Input LDO

Application Information (Continue)

Protection Diode

In normal operation TS1582 family does not need any protection diodes between the Adjust pin and the output and

from the output to the input to prevent die overstress. Internal resistors are limiting the internal current paths on the

Adjust pin. Therefore even with bypass capacitors on the Adjust pin no protection diode is needed to ensure device

safety under short-circuit conditions. The Adjust pin can be driver on a transient basis +/-7V with respect to the output

without any device degradation.

A protection diode between the Output pin and Vpower pin is not usually needed. Microsecond surge currents of 50A

to 100A can be handled by the internal diode between the Output pin and Vpower pin of the device. In normal

operations it is difficult to get those values of surge currents even with the use of large output capacitances. Only with

high value output capacitors, such as 1000uF to 5000uF and the Vpower pin is instantaneously shorted to ground,

damage can occur. A diode from output to input is recommended.

If TS1582 is connected as a single supply device with the control and power input ins shorted together the internal

diode between the output and the power input pin will protect the control input pin.

Thermal Considerations

The TS1582 family have internal power and thermal limiting circuit designed to protect the device under overload

conditions. However maximum junction temperature ratings should not be exceeded under continuous normal load

conditions. Careful consideration must be given to all sources of thermal resistance from junction to ambient, including

junction-to-case, case-to-heat sink interface and heat sink resistance itself. Junction temperature of the Control section

can urn up to125ºC. Junction temperature of the Power section can run up to 150ºC. Due to the thermal gradients

between the power transistor and the control circuitry there is a significant difference in thermal resistance between the

Control and Power sections.

Virtually all the power dissipated by the device is dissipated in the power transistor. The temperature rise in the power

transistor will be greater than the temperature rise in the Control section making the thermal resistance lower in the

Control section. At power levels below 12W the temperature gradient will be less than 25ºC and the maximum ambient

temperature will be determined by the junction temperature of the Control section. This is due to the lower maximum

junction temperature in the Control section. At power levels above 12W the temperature gradient will be greater than

25ºC and the maximum ambient temperature will be determined by the Power section. In both cases the junction

temperature is determined by the total power dissipated in the device. For most low dropout applications the power

dissipation will be less than 12W.

The power in the device is made up of two components: the power in the output transistor and the power in the control

circuit.

The power in the control circuit is negligible.

The power in the control circuit is equal to:

Pcontrol = ( Vcontrol – Vout ) ( Icontrol )

Where Icontrol is equal Iout / 100 (typ)

The power in the out transistor is equal to:

Poutput = ( Vpower – Vout ) ( Iout )

The total power is equal to:

Ptotal = Pcontrol + Poutput

Junction-to-case thermal resistances is specified from the IC junction to the bottom of the case directly below the die.

This is the lowest resistance path for the heat flow. In order to ensure the best possible thermal flow this area of the

package to the heat sink proper mounting is required. Thermal compound at the case-to-heat sink interface is

recommended. A thermally conductive spacer can be used, if the case of the device must be electrically isolated, but

its added contribution to thermal resistance has to be considered.

6/9

Version: A07

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