Texas Instruments TPS6021 Series, Руководство пользователя

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1-1
Description of the EVM
The Texas Instruments TPS60210 charge pump is a regulated voltage dou-
bler. The TPS60210 delivers 3.3-V output voltage (V
O
) from a 1.8-V to 3.6-V
input voltage (V
I
). The output current (I
O
) is 100 mA minimum, for an input volt-
age (V
I
) of 2.0 V or higher.
For output currents below 2 mA, the device can be operated in the snooze
mode (SNOOZE = 0). This is an operating mode, where the quiescent current
is drastically reduced. In this mode, V
O
is regulated to 3.3 V
±
6%. The low
quiescent current is achieved by disabling most of the internal circuitry as long
as V
O
is high enough. When V
O
decreases, the device operates for a short pe-
riod of time in normal mode, to boost V
O
. The internal circuitry is then disabled
again. This reduces the quiescent current to a typical value of only 2
µ
A. If the
device is programmed to operate in snooze mode and the I
O
increases above
2 mA, the device enters the startup mode to increase V
O
.
Additionally, the TPS60210 has a low battery detector (LBI input and LBO
output). The trip voltage of the LBI input is typically 1.18 V. The TPS60210 can
be programmed with an external resistive divider to the specific trip voltage for
the application. On the EVM, the resistive divider on the LBI input is connected
to V
I
and the trip voltage is set to 2.0 V, typically. The LBO output is an
open-drain output and is in a high-impedance state as long as the voltage at
LBI is above the trip voltage. A 1-M
Ω
pullup resistor to V
O
is added on the EVM
to get a defined high signal as long as the voltage at LBI is above the trip
voltage.
For simple evaluation, a 1-M
Ω
resistor between V
I
and the SNOOZE pin is
added to operate the TPS60210 in normal mode.
A minimum of four external capacitors for a push-pull voltage doubler charge
pump are required. The EVM is built with these four capacitors. For evaluation,
it is possible to use other capacitor values like those given in the application
section of the TPS6021x data sheet (literature number SLVS296). The capaci-
tors on the EVM are ceramic capacitors. The ESR of all other capacitor types
is too high to get good performance.
Chapter 1