Functional description

L5954

10/15

Doc 17717 Rev 1

3

Functional description

The three high side drivers are a 2.0 A output (HSD1), and two 450 mA outputs (HSD2 and

3). The five regulator outputs are a 10 V at 350 mA (REG1), an 8.5 V at 175 mA (REG2), a

5 V at 350 mA (REG3), an 8 V/1 0V at 1 A (REG4), and 5 V at 250 mA (REG5). The

regulators are low dropout. The regulators will operate with output capacitors with ESR of

0.1

Ω to 5 Ω.

REG3 is referenced from the VREF input not the internal bandgap. This is done to minimize

the voltage offset between individual 5 V supplies.

The REG2 and REG3 outputs are turned on and off with the Enable input, a '1' turns the

outputs on and a '0' turns them off. When Enable is "1", the other outputs can be

guaranteed to be lower than 0.2 V. The output voltage of REG4 is selected via bit 5 of the

run at a clock speed range of 100 kHz to 400 kHz. This device should be capable of

operating at any frequency within this range.

3.1

Protection

The L5954 can survive under the following conditions: shorting the outputs to BAT and GND,

loss of BAT, loss of IC GND, double battery, ESD, 34V load dump. L5954 will not handle a

reverse battery condition. External components must be implemented for reverse battery

protection.

3.1.1

Thermal shutdown

REG1, REG2, REG3, REG4, REG5 outputs shutdown at 160 °C and return to normal

operation at 130 °C. The HSD2 and HSD3 shutdown at 160 °C and return to normal

operation at 130 °C. The HSD1 with go into thermal shutdown at 170 °C and returns to

operation at 120 °C.

3.1.2

Current limiting

Each voltage regulator will contain its own current protection.

3.1.3

Short circuit

If the outputs are short circuited, the IC will go into current limiting and eventually the

thermal shutdown will kick in. Current limiting will not disable the outputs.

Obsolete

Product(s)

- Obsolete

Product(s)