STOD03A datasheet(17/22 Pages) STMICROELECTRONICS

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DocID17785 Rev 3

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STOD03A

Application information

are in an OFF state so the load is electrically disconnected from the input, this avoids

unwanted current leakage from the input to the load.

When the EN is pulled high, the P1B switch is turned on for 100 µs. In normal operation,

during this time, apart from a small drop due to parasitic resistance, VMID reaches VIN.

If, after this 100 µs, VMID stays below VIN, the P1B is turned off and stays off until a new

pulse is applied to the EN. This mechanism avoids STOD03A starting if a short-circuit is

present on VMID.

7.3.3

Soft-start and inrush current limiting

After the EN pin is pulled high, or after a suitable voltage is applied to VINP, VINA, and EN,

the device initiates the startup phase.

As a first step, the CMID capacitor is charged and the P1B switch implements a current

limiting technique in order to keep the charge current below 400 mA. This avoids the battery

overloading during startup.

After VMID reaches VINP voltage level, the P1B switch is fully turned on and the soft-start

procedure for the step-up is started. After about 2 ms the soft-start for the inverting is

started. The positive and negative voltage is under regulation by around 6 ms after the EN

pin is asserted high.

7.3.4

Undervoltage lockout

The undervoltage lockout function avoids improper operation of STOD03A when the input

voltage is not high enough. When the input voltage is below the UVLO threshold the device

is in shutdown mode. The hysteresis of 50 mV avoids unstable operation when the input

voltage is close to the UVLO threshold.

7.3.5

Overtemperature protection

An internal temperature sensor continuously monitors the IC junction temperature.

If the IC temperature exceeds 140 °C, typical, the device stops operating. As soon as the

temperature falls below 125 °C, typical, normal operation is restored.

7.3.6

Fast discharge

When ENABLE turns from high to low level, the device goes into shutdown mode and LX1

and LX2 stop switching. Then, the discharge switch between VMID and VIN and the switch

between VO2 and GND turn on and discharge the positive output voltage and negative

output voltage. When the output voltages are discharged to 0 V, the switches turn off and

the outputs are high impedance.

STOD03A Datasheet(PDF) 17 Page - STMicroelectronics