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Description
5
Description
The following paragraphs describe the UCD90120/4 EVM functionality and operation.
5.1
Communication Interfaces
Several communication interfaces to the UCD90120/4 are provided on the EVM.
5.1.1
USB Interface
An onboard USB to PMBus interface is provided through the USB Input (J3) connector. D56 provides USB
attach status. The presence of USB power at J3 activates buffer circuitry which gives control of the PMBus
to the on board circuitry. The absence of USB power at J3 gives PMBus control through the Expansion
PMBus (J77) connector.
5.1.2
PMBus
Standard PMBus interface is provided to the UCD90120/4 through the J77 connector when the on EVM
USB-PMBus interface is not used. PMBus addressing is set using the J18 jumper block for ADDRSENS1
and ADDRSENS0 respectively. ADDRx=8 and ADDRx=5 positions for each are provided. The EVM
comes with PMBus address set to 101 decimal.
PMBus Address (decimal) = 12 × ADDR1 + ADDR0 jumper block setting.
5.1.3
JTAG
Standard JTAG programming interface is provided to the UCD90120/4 through the J9 connector. Install
J6, J7, J11, and J12 jumpers and ensure that rail 9-12 enable jumpers (J47, J53, J59, J65) are removed
when using the JTAG interface.
5.2
Power
5.2.1
Input Power
The 12VDC EVM input power is provided through J1 (standard DC jack) or J2 (screw jack). A wall or
laptop adapter with 500mA (UCD90120EVM) or 2000mA (UCD90124EVM running a fan) capability and
2.5mm I.D. x 5.5mm O.D. x 9.5mm DC jack can power the EVM. Reverse voltage protection and inrush
limiting is provided for 12VBUS. The 12VBUS signal is distributed for fan power and Local 3.3V supply.
5.2.2
5VBUS
5VBUS is derived from 12VBUS and provides the input voltage for rails 1-12. D5 will illuminate when
5VBUS is present.
5.2.3
L3P3V
L3P3V is derived from 5VBUS and provides a general purpose 3.3V supply for the common onboard
functions. The L3P3V jumper (J4) is installed to provide a connection to the 3P3V node.
5.2.4
V33D
The V33D node is connected to the UCD90120/4 digital and analog supply pins. V33D can be sourced by
3P3V or Local V33D using the J5 jumper. D9 will illuminate when V33D is present.
5.2.5
Local 3.3V
The UCD90120/4 can be powered from 12VBUS using the local V33D supply. Install J13 (12VB) and
ensure J5 is installed in the LV33D position to use the local regulator.
15
SLVU347 – December 2009
Evaluation Module for UCD90120 and UCD90124
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