AN2229 STMICROELECTRONICS | Alldatasheet

Document overview

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  • PDF pages: 8

Technical content

Datasheet sections

  • 1 Explanation of 2 possible Startup Behaviors
  • 2 Application example using standby voltage monitoring
  • 3 Proposed initialization sequences for L9903:
  • 4 Proposed initialization sequences L9904:
  • 5 Revision history

Startup Behavior L9903/L9904 Introduction Purpose of the Application Note is to detail the startup behaviour of L9903 and L9904 devices and to explain a correct initialization sequence, possibly being necessary when application configuration is different from the one suggested inside datasheet. In fact, in case an additional, external diagnostic structure is used, it may happen that after a first connection of the supply voltage, and before first enabling of the device, the measurement results of these diagnostic structure is not precise.

1 Explanation of 2 possible Startup Behaviors

Starting condition: the device is disconnected from the battery. a) Gate of high side driver is internally switched to ground (Fig. 1). b) Gate of high side driver is internally switched to CBx (Fig. 2). After the first VS ramp up the outputs will enter one of the explained states. be enabled by the EN pin. The only consequence of entering state 2 is an increased leakage current. initialization is needed (see sections 3 and 4). Figure 1. Startup behavior internal switched Figure 2. Startup behavior internal switch to

2 Application example using standby voltage monitoring AN2229

2 Application example using standby voltage

Figure 3. DC motor driving wi th additional diagnostic (RD1, RD2, RD3) measure a potential short circuit or open load condition. monitoring voltage levels of the resistive network. not influenced. Later standby modes are also not influenced.

3 Proposed initialization sequences for L9903:

Figure 4. Proposed Sequence to Initialize L9903 after V S is applied circuit to setup. A signal change within the 50μs may not be detected.

4 Proposed initialization sequences L9904: AN2229

4 Proposed initialization sequences L9904:

Figure 5. Proposed Sequence to Initialize L9904 after V S is applied

5 Revision history

October 2005 1 Initial release. 23-Sep-2013 2 Updated Disclaimer.