 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
LAN8187i Datasheet(PDF) 31 Page - SMSC Corporation |
|
||||||||||||||||||||||||||||||
LAN8187i Datasheet(HTML) 31 Page - SMSC Corporation |
|
|
31 / 78 page  ±15kV ESD Protected MII/RMII 10/100 Ethernet Transceiver with HP Auto-MDIX & flexPWR® Technology Datasheet SMSC LAN8187/LAN8187i 31 Revision 1.7 (03-04-11) DATASHEET 4.9 Internal +1.8V Regulator Disable One feature of the flexPWR technology is the ability to to configure the internal 1.8V regulator off. When the regulator is disabled, external 1.8V must be supplied to VDD_CORE. This makes it possible to reduce total system power, since an external switching regulator with greater efficiency than the internal linear regulator may be used to provide the +1.8V to the PHY circuitry. 4.9.1 Disable the Internal +1.8V Regulator To disable the +1.8V internal regulator, a pulldown strapping resistor (see Table 4.4, “Boot Strapping Configuration Resistors,” on page 33) is attached from REG_EN to VSS. When both VDDIO and VDDA are within specification, the PHY will sample the REG_EN pin to determine if the internal regulator should turn on. If the pin is grounded to VSS, then the internal regulator is disabled, and the system must supply +1.8V to the VDD_CORE pin. The voltage at VDD33 must be at least 2.64V (0.8 * 3.3V) before voltage is applied to VDD_CORE. As descibed in Section 4.9.2, when the REG_EN pin is left floating or pulled up to VDDIO, then the internal regulator is enabled and the system does not supply +1.8V to the VDD_CORE pin. When the +1.8V internal regulator is disabled, a 0.1uF capacitor must be added at the VDD_CORE pin and placed close to the PHY. This capacitance provides decoupling of the external power supply noise. 4.9.2 Enable the Internal +1.8V Regulator To enable the internal regulator, a pull-up resistor (see Table 4.4, “Boot Strapping Configuration Resistors,” on page 33) to VDDIO may be added to the REG_EN pin. When the REG_EN pin is left floating, the internal regulator will aslo be enabled. Both a 4.7uF low-ESR and a 0.1uF capacitor must be added at the VDD_CORE pin and placed close to the PHY. This capacitance ensures stability of the internal regulator. Figure 4.4 Direct cable connection vs. Cross-over cable connection. |
Similar Part No. - LAN8187i |
|
Similar Description - LAN8187i |
|
|
Link URL |
| Privacy Policy |
| ALLDATASHEET.COM |
| Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
| Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
|
Family Site : ic2ic.com |
icmetro.com |
English ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
