AN4243 datasheet(18/29 Pages) STMICROELECTRONICS

18 / 29 page

Designing an application with the L6230

AN4243

18/29

Doc ID 024199 Rev 1

The external RC network, CEN in particular, must be chosen obtaining a reasonable fast

OCD intervention (short tDELAY) and a safe disable time (long tDISABLE).

Figure 15 shows both tDISABLE and tDELAY as a function of CEN: at least 100µs for tDISABLE

are recommended, keeping the delay time about 1 to 2µs at the same time.

Figure 15.

Typical disable time vs. CEN (on varying REN)

Figure 16.

Typical delay time vs. CEN

The internal open-drain can also be turned on if the device experiences an overtemperature

(OVT) condition. The OVT causes the device to shut down when the die temperature

exceeds the OVT threshold (TJ > 165 °C typ.). Since the OVT is also connected directly to

the gate drive circuit (see Figure 1), all the power DMOS shut down, even if DIAG-EN pin

voltage is still over Vth(OFF). When the junction temperature falls below the OVT turn-off

threshold (150 °C typ.), the open-drain turns off, CEN is recharged up to VTH(ON) and then

the power DMOS are turned back on.

2.11

Thermal management

In most applications, the power dissipation in the IC is the main factor that sets the

maximum current that can be delivered by the device in a safe operating condition.

Therefore, it has to be taken into account very carefully. Besides, the available space on the

1 0

100

10 0

1 .10

C EN [n F ]

R EN = 2 2 0

Ω k

R EN = 1 0 0

Ω k

R EN = 47

Ω k

R EN = 33

Ω k

R EN = 10

Ω k

AM16577v1

11 0

1 0 0

0. 1

C EN [n F ]

AM16578v1

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