STFPC311 View Datasheet(PDF) - STMicroelectronics

Part Name

Description

MFG CO.

STFPC311

Front panel controller/driver with standby power management

STMicroelectronics 

STFPC311

10 Maximum rating

10.1 Power consumption estimation

The maximum power consumption is comprised of the Vacuum Florescent Display (VFD) driver

dissipation, Load Resistance (RL), LED driver dissipation, and dynamic power consumption.

PMAX = VFD + RL + LED + PDYN

Where,

● PMAX = maximum power consumption,

● VFD = Vacuum Florescent Display driver dissipation,

● RL = load resistance,

● LED = LED driver dissipation, and

● PDYN = dynamic power consumption.

If the segment current (ISEG) = 3mA, grid current (IGRID) = 15mA, and the LED current =

20mA, then:

FIP = (#segments x 6) + [#grids/(#grids +1)] x 30mW,

RL dissipation = (VDD – VSS)2 ÷ 50(segment + 1mW),

LED driver dissipation = #LEDs x 20mW, and

PDYN = VDD x 5mW.

To finish this example:

FIP driver dissipation = 16 x 6 + 12/13 x 30 = 124mW

RL dissipation = 33.32/50 x 17 = 377mW

LED driver dissipation = 2 x 20 = 40

PDYN = 3.3 x 5 = 16.5mW

The maximum power consumption (Total) = 557.5mW

Where,

VSS = –30V,

VDD = 3.3V, and the application is in 16-segment, 12-digit mode.

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