On-chip voltage regulator (VREG)

AN2871

10/25

Doc ID 15304 Rev 3

Note:

The BC817-16 variant is also compatible with the SPC560Px voltage regulator.

BCX68-25 NPN bipolar 0.5 A SOT89

This transistor is available from several semiconductor makers.

Note:

BCX68-16 and BCX68-10 variants are also compatible with the SPC560Px voltage

regulator.

Summary of proposed ballast transistors

The transistors list of Table 1 has been validated by simulations. To offer several options to

ECU designers, various packages are proposed:

●

SOT223 for BCP68

●

SOT89 for BCX68-25, BCX68-16, and BCX68-10

●

SOT23 for BC817-25 and BC817-16

Please note that the SOT23 package has a high thermal resistance and is not suited for the

full automotive temperature range.

BC817-25 is also offered in the SC74 package, which has a better thermal resistance but

that still does not allow using this transistor in the full temperature range.

The SOT23 and SC74 packages should be considered for applications such as airbags.

Figure 4.

Example of temperature response from NXP BC817-25

Table 4.

Zetex datasheet: BCX68-25 electrical characteristics at 25 °C

Symbol

Parameter

Min

Typ

Max

Unit

—

DC current gain

160

—

400

—