CTRL

8ms Typ.

TPS65138

TPS65138A

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SLVSAV3C – APRIL 2011 – REVISED MAY 2012

DETAIL DESCRIPTION

The TPS65138 consists of a boost converter and an inverting buck boost converter. The positive output is fixed

at 4.62V. Negative output is programmable by a digital interface, and TPS65138 has the range of -2.2V to

approximately -6.2V and TPS65138A has the range of -2.2V to approximately -5.2V. Both TPS65138 and

TPS65138A have -4.9V of the default negative output. The transition time of the negative output is adjustable by

the CT pin capacitor.

SOFT START and START-UP SEQUENCE

The device has soft start to limit in rush current. When the device is enabled by CTRL pin going HIGH, the boost

converter starts with reduced switch current limit. 8 ms after CTRL HIGH, Buck boost converter starts with the

Figure 8. Start-up Sequence

SHORT CIRCUIT PROTECTION

The device is protected against short circuits of the outputs to ground and short circuit of the outputs each other.

above -1 V for more than 3 ms. In either case, the device goes into shutdown and this state is latched. Input and

LOW and HIGH.

During start up, an error condition is detected in the following cases:

For these cases, the device goes into shutdown and this state is latched. Input and outputs are disconnected. To

ENABLE (CTRL PIN)

The CTRL pin serves two functions. One is to enable and disable the device the other is the output voltage

programming of the device. If the digital interface is not required the CTRL pin can be used as a standard enable

the device is enabled. The device is shut down with CTRL low.

DIGITAL INTERFACE (CTRL PIN)

voltage setting is not required then the CTRL pin can also be used as a standard enable pin. The digital output

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Product Folder Links: TPS65138 TPS65138A