Texas Instruments TPS2231EVM - Manual (Page 15)

Features
3-3 EVM Operation
3.4 Features
In order to easily evaluate the TPS2231 PD controller, the EVM features are
described in this section.
3.4.1 Input and Output Capacitors
The input capacitances of the TPS2231 voltage inputs are recommended to
be at least 4.7
µ
F. The output capacitances are at least 0.1
µ
F but greater
output capacitance will improve system performance during transients. The
ExpressCard specifications defines the total host and card capacitance to be
less than 100
µ
F. The EVM has one 0.1-
µ
F capacitor and a 68-
µ
F capacitor
on each of the three voltage outputs.
3.4.2 LEDs
Four LEDs are installed on the HPA074 EVM to indicate the states of the three
voltage outputs and the OC flag. When there is an overcurrent condition at any
of the internal power switches of the TPS2231, D1 will be turned on. If D2 is
on, 1.5VOUT is within its regulation range. Similarly, D3 indicates the voltage
of AUXOUT, and D4 is for 3.3VOUT.
3.4.3 Clock Oscillator
A 10-MHz clock is generated by U3 and it can be tested at TP10. The RCLKEN
signal of the TPS2231, when it is high, will enable drivers (U2 and U4) to have
an inverting clock output at TP8 and a noninverting clock output at TP9, and
both are passed to the ExpressCard socket at J2.
3.4.4 ExpressCard Socket
An Expresscard compliant card socket J2 is installed. It can be used to evalu-
ate the TPS2231 with an ExpressCard card (not supplied with the HPA074
EVM) inserted.