TPS65130, TPS65131

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SLVS493C – MARCH 2004 – REVISED JUNE 2015

Feature Description (continued)

7.3.2 Control

The controller circuits of both converters employ a fixed-frequency, multiple-feedforward controller topology. The

circuits monitor input voltage, output voltage, and voltage drop across the switches. Changes in the operating

conditions of the converters directly affect the duty cycle and must not take the indirect and slow way through the

output voltage control loops. Measurement errors in this feedforward system are corrected by a self-learning

control system. An external capacitor damps the output to avoid output-voltage steps due to output changes of

this selflearning control system.

The voltage loops, determined by the error amplifiers, must only handle small signal errors. The error amplifiers

feature internal compensation. Their inputs are the feedback voltages on the FBP and FBN pins. The device

uses a comparison of these voltages with the internal reference voltage to generate an accurate and stable

output voltage.

7.3.3 Enable

Both converters can be enabled or disabled individually. Applying a logic HIGH signal at the enable pins (ENP for

the boost converter, ENN for the inverting converter) enables the corresponding output. After enabling, internal

circuitry, necessary to operate the specific converter, then turns on, followed by the Soft-Start.

AApplying a low signal at the enable ENP or ENN pin shuts down the corresponding converter. When both

enable pins are low, the device enters shutdown mode, where all internal circuitry turns off. The device now

consumes shutdown current flowing into the VIN pin. The output loads of the converters can be disconnected

from the input, see Load Disconnect.

7.3.4 Load Disconnect

The device supports completely disconnecting the load when the converters are disabled. For the inverting

converter, the device turns off the internal PMOS switch. If the inverting converter is turned off, no DC current

path remains which could discharge the battery or supply.

This is different for the boost converter. The external rectifying diode, together with the boost inductor, form a DC

current path which could discharge the battery or supply if any load connects to the output. The device has no

internal switch to prevent current from flowing. For this reason, the device offers a PMOS gate control output

(BSW) to enable and disable a PMOS switch in this DC current path, ideally directly between the boost inductor

and battery. To be able to fully disconnect the battery, the forward direction of the parasitic backgate diode of this

switch must point to the battery or supply. The external PMOS switch, which connects to BSW, turns on when

the boost converter is enabled and turns off when the boost converter is disabled.

7.3.5 Soft-Start

Both converters have implemented soft-start functions. When each converter is enabled, the implemented switch

current limit ramps up slowly to its nominal programmed value in about 1 ms. Soft-start is implemented to limit

the input current during start-up to avoid high peak currents at the battery which could interfere with other

systems connected to the same battery. Without soft-start, the high input peak current could trigger the

implemented switch current limit, which can lead to a significant voltage drops across the series resistance of the

battery and its connections.

7.3.6 Overvoltage Protection

Both converters (boost and inverter) have implemented individual overvoltage protection. If the feedback voltage

under normal operation exceeds the nominal value by typically 5%, the corresponding converter shuts down

immediately to protect any connected circuitry from possible damage.

7.3.7 Undervoltage Lockout

An undervoltage lockout (UVLO) prevents the device from starting up and operating if the supply voltage at the

VIN pin is lower than the undervoltage lockout threshold. For this case, the device automatically shuts down both

converters when the supply voltage at VIN falls below this threshold. Nevertheless, parts of the control circuits

remain active, which is different than device shutdown.

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