PD64012 Datasheet, PDF (5/16 Pages) List of Unclassifed Manufacturers – 12-channel PoE Manager

PD64012
12-CHANNEL PoE MANAGER
P_main = V_main x I _main
P_main typ. = 48 VDC x 10 mA = 0.480 W_.
P_main max. = 57 VDC x 15 mA = 0.855 W
Device Power Dissipation – the PD64012 incorporates 12 power MOSFETs, each characterized by:
Resistance from drain-source R_ds(on) = 0.3 Ω typ. ; 0.5 Ω max.
Drain-source current I_ds = 360 mA max.
Maximum power dissipation P_MOSFET max. of a single PD64012 device (for 12 MOSFETs) :
[(I_ds)² x R_ds(on)] x 12 = [(0.36 A)² x 0.5 Ω] x 12 = 0.78 W
Charge pump (see Analog Section of Block Diagram Description, hereafter) power dissipation P_CP is 0.21 W.
Total power dissipation P_total by device, under maximum conditions:
P_total = P_main max. + P_MOSFET max. + P_CP = 0.855 W + 0.78 W + 0.21 W = 1.845 W
OVL_S
I_lim
I_cut
T_cut
OVL
I_channel
Port 1
Port 2
I_min
Port off
UDL_S
UDL
T_min
Figure 2: Power Limits
Protection Mechanism
The PD64012 includes internal thermal protection to avoid junction overheat. Three types of temperature sensors
are integrated into the device: two are used for protection and one for temperature monitoring.
Hi-temp protection – the device contains thermal shutdowns. This protection system is activated in extreme
conditions.
Lo-temp protection – there are thermal sensors that are intended to protect the functionality of the device, in
cases of temperature rise.
Indicator sensors – four temperature sensors monitor the local temperature in the device. Their average is also
calculated by the PD64012. All values are stored in internal registers for data retrieval. The register values are
calculated by:
Decimal value = 684 - 1.514 x [(T_junc)+ 40 °C].
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06-0003-058 (Rev. 2.8) / 5 August 2004
© PowerDsine 2003
Information in this document subject
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