Datasheet

TPS65140, TPS65141
TPS65145
www.ti.com SLVS497E –SEPTEMBER 2003–REVISED NOVEMBER 2012
Power-Good Output
The TPS6514x sereis has an open-drain power-good output with a maximum sink capability of 1 mA. The power-
good output goes high as soon as the main boost converter V
O
1 and the negative and the positive charge pumps
are within regulation. The power-good output goes low as soon as one of the outputs is out of regulation. In this
case, the device goes into shutdown at the same time. See the electrical characteristics table for the power-good
thresholds.
Enable and Power-On Sequencing (EN, ENR)
The device has two enable pins. These pins should be terminated and not left floating to prevent faulty operation.
Pulling the enable pin (EN) high enables the device and starts the power-on sequencing with the main boost
converter V
O
1 coming up first, then the negative and positive charge pump. The linear regulator has an
independent enable pin (ENR). Pulling this pin low disables the regulator, and pulling this pin high enables this
regulator.
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.
Positive Charge Pump
The TPS6514x series has a fully regulated integrated positive charge pump generating V
O
3. The input voltage
for the charge pump is applied to the SUP pin that is equal to the output of the main boost converter V
O
1. 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 V
O
1 and V
O
3. See Figure 13 and Figure 14.
Negative Charge Pump
The TPS6514x sereis 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
V
O
1. 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 V
O
1 and
V
O
2. See Figure 12.
Linear Regulator Controller
The TPS6514x series 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). Since most of the systems require this voltage rail to come up first it is recommended
to use a R-C delay on EN. This delays the start-up of the main boost converter which reduces the inrush current
as well.
Soft Start
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 V
O
1 during start-
up. See Figure 10 and Figure 11. During softstart of the main boost converter V
O
1 the internal current limit
threshold is increased in three steps. The device starts with the first step where the current limit is set to 2/5 of
the typical current limit (2/5 of 2.3A) for 1024 clock cycles then increased to 3/5 of the current limit for 1024 clock
cycles and the 3rd step is the full current limit. The TPS65141 has an extended softstart time where each step is
2048 clock cycles.
Fault Protection
All of the outputs of the TPS65140/45 have short-circuit detection and cause the device to go into shutdown. The
TPS65141, as an exception, does not enter shutdown in case one of the outputs falls below its power good
threshold. The main boost converter has overvoltage and undervoltage protection. If the output voltage V
O
1 rises
above the overvoltage protection threshold of typically 5% of V
O
1, 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 V
O
1, because of a short-
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