TPS60500, TPS60501
TPS60502, TPS60503
SLVS391B − OCTOBER 2001 − REVISED FEBRUARY 2002
PRINCIPLES OF OPERATION
The TPS6050x charge pumps provide a regulated output voltage in the range of 0.8 V to 3.3 V from an input
voltage of 1.8 V to 6.5 V. The devices use switched capacitor fractional conversion to achieve high efficiency
over the entire input and output voltage range. Regulation is achieved by sensing the output voltage and
enabling the internal switches as needed to maintain the selected output voltage. This skip-mode regulation is
used over a load range from 0 mA to 150 mA. At a higher output current, the device works in a linear regulation
mode.
The TPS6050x circuits consist of an oscillator, a voltage reference, an internal resistive feedback circuit (fixed
voltage version only), an error amplifier, two charge pump stages with MOSFET switches, a shutdown/start-up
circuit, and a control circuit.
short-circuit current limit and thermal protection
When the output voltage is lower than 0.6 V, the output current is limited to 300 mA typically. The device also
has a thermal protection which reduces the output current when the temperature of the chip exceeds 150°C.
The output current declines to 0 mA when the chip temperature rises to 160°C.
enable
Driving EN high disables the converter. This disables all internal circuits, reducing input current to only 0.05µA.
Leakage current drawn from the output pin OUT is a maximum of 1
µA.
The device exits shutdown once EN
is set low (see start up procedure described below). The typical no-load start-up time is 80
µs.
When the device
is disabled, the load is isolated from the input, an important feature in battery-operated products because it
extends the battery shelf life.
start-up procedure
The device is enabled when EN is set from logic high to logic low. The charge pump stages immediately start
switching to transfer energy to the output. In start-up until the output voltage has reached 0.6 V, the input current
is limited to 300 mA typically.
power good detector
The power good (PG) output is an open-drain output on all TPS6050x devices. The PG output pulls low when
the output is out of regulation. When the output rises to within 97% of regulation, the power good output goes
high. In shutdown, power good is pulled low. In normal operation, an external pullup resistor is typically used
to connect the PG pin to V
O
or V
I
. If the PG output is not used, it should remain unconnected.
VO
V(NOM)
VIT
td,r
PG
1
td,r
td,f
t
0
t
EN
1
0
t
Figure 21. Power Good Timing Diagram
www.ti.com
9
TI [ TEXAS INSTRUMENTS ]
