Positive Charge Pump

Negative Charge Pump

Linear Regulator Controller

Soft Start

Fault Protection

Thermal Shutdown

TPS65140-Q1

TPS65145-Q1

If the enable pin (EN) is pulled high, the device starts its power-on sequencing. The main boost converter starts

up first with its soft start. If the output voltage has reached 91.25% of its output voltage, the negative charge

pump comes up next. The negative charge pump starts with a soft start and when the output voltage has

reached 91% of the nominal value, the positive charge pump comes up with the soft start.

Pulling the enable pin low shuts down the device. Dependent on load current and output capacitance, each of

the outputs comes down.

The TPS65140/45 has a fully regulated integrated positive charge pump generating Vo3. The input voltage for

the charge pump is applied to the SUP pin that is equal to the output of the main boost converter Vo1. The

charge pump is capable of supplying a minimum load current of 20 mA. Higher load currents are possible

depending on the voltage difference between Vo1 and Vo3. See Figure 13 and Figure 14.

The TPS65140/45 has a regulated negative charge pump using two external Schottky diodes. The input voltage

for the charge pump is applied to the SUP pin that is connected to the output of the main boost converter Vo1.

The charge pump inverts the main boost converter output voltage and is capable of supplying a minimum load

current of 20 mA. Higher load currents are possible depending on the voltage difference between Vo1 and Vo2.

See Figure 12.

The TPS65140/45 includes a linear regulator controller to generate a 3.3-V rail which is useful when the system

is powered from a 5-V supply. The regulator is independent from the other voltage rails of the device and has its

own enable (ENR).

The main boost converter as well as the charge pumps and linear regulator have an internal soft start. This

avoids heavy voltage drops at the input voltage rail or at the output of the main boost converter Vo1 during

start-up caused by high inrush currents. See Figure 10 and Figure 11.

All of the outputs of the TPS65140/45 have short-circuit detection and cause the device to go into shutdown. The

main boost converter has overvoltage and undervoltage protection. If the output voltage Vo1 rises above the

overvoltage protection threshold of typically 5% of Vo1, then the device stops switching, but remains operational.

When the output voltage falls below this threshold, the converter continues operation. When the output voltage

falls below the undervoltage protection threshold of typically 8.75% of Vo1, because of a short-circuit condition,

the TPS65140/45 goes into shutdown. Because there is a direct pass from the input to the output through the

diode, the short-circuit condition remains. If this condition needs to be avoided, a fuse at the input or an output

disconnect using a single transistor and resistor is required. The negative and positive charge pumps have an

undervoltage lockout (UVLO) to protect the LCD panel of possible latch-up conditions due to a short-circuit

condition or faulty operation. When the negative output voltage is typically above 9.5% of its output voltage

(closer to ground), then the device enters shutdown. When the positive charge pump output voltage, Vo3, is

below 8% typical of its output voltage, the device goes into shutdown. See the fault protection thresholds in the

electrical characteristics table. The device is enabled by toggling the enable pin (EN) below 0.4 V or by cycling

the input voltage below the UVLO of 1.7 V. The linear regulator reduces the output current to 20 mA typical

under a short-circuit condition when the output voltage is typically < 1 V. See the Functional Block Diagram. The

linear regulator does not go into shutdown under a short-circuit condition.

A thermal shutdown is implemented to prevent damage due to excessive heat and power dissipation. Typically,

the thermal shutdown threshold is 160

°C. If this temperature is reached, the device goes into shutdown. The

device can be enabled by toggling the enable pin to low and back to high or by cycling the input voltage to GND

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Product Folder Link(s): TPS65140-Q1 TPS65145-Q1