USB97C243 SMSC [SMSC Corporation], USB97C243 Datasheet - Page 3

• Manufacturer Part Number: USB97C243
• Description: capacitor Selection for Internal Regulator Output Pins
• Manufacturer: SMSC [SMSC Corporation]

USB97C223 and USB97C243 Capacitor Selection for Internal Regulator Output Pins
Overview
Requirements
SMSC AN 10.8
Figure 1 - 10uF Capacitor with 0.1 Ohm ESR
The USB97C223 and USB97C243 have two internal 1.8V regulators used to provide the digital and analog 1.8V
supplies. The output pins of the regulator have very specific capacitor requirements that are described below.
It is important that the customer designs their product with the specifications set forth in this document.
Table 1 lists the capacitor requirements on the regulator output pins.
Figure 1 and Figure 2 show an example of the degradation in performance of the USB97C223 and USB97C243
as the ESR of the capacitor on the output of the regulators is increased to 0.65 Ohm.
PIN NUMBER
98
91
50
43
VDDCORE (closest
VDDCORE
PIN NAME
to VREG)
VDDP
VDDP
APPLICATION NOTE
Table 1 – Regulator Output Pins
Analog Regulator
Output
Digital Regulator
Output
Analog Regulator
Output
Digital Regulator
Output
USB97C223
USB97C243
PIN DESCRIPTION
Page 3
Figure 2 - 10uF Capacitor with 0.65 Ohm ESR
10uF +/- 20 % with < 0.65 Ohm ESR
10uF +/- 20 % with < 0.65 Ohm ESR
10uF +/- 20 % with < 0.65 Ohm ESR
10uF +/- 20 % with < 0.65 Ohm ESR
CAPACITOR REQUIREMENT
Rev. 12-16-03