AN2503 Datasheet, PDF (11/30 Pages) STMicroelectronics – PDP Power Devices

AN2503
Figure 12. Circuit scheme
Vs
Vs
Vset
PDP Sustain circuit
Vs
Vs
CS1
T3
D2
D3
T2
L1
T6
T1
D1
D4
T4
T7
T5
T9
Cp
T8
L7
T10
-Vreset
D8
D5
T11
T12
D7
D6
CS2
Weber topology provides a new sustainer circuit that recovers the energy otherwise lost in
charging and discharging the panel capacitance, Cp. The efficiency with which the sustainer
recovers this energy is defined as the "recovery" efficiency. In particular, when Cp is
charged
C_PV_S2.
to
V_s
and
then
discharged
to
zero,
the
energy
that
flows
into
and
out
of
Cp
is
E
=
The recovery efficiency is defined by:
Equation 1
Eff
=
100 •
C_-----P---V_-----S---²_{----–-----}E_{----L---O----S---T--}
C_PV_S2
=
100
•
⎛
⎜1
⎝
–
C^{-E----LP---O-}V^---S-_S^{--T-2-⎠⎟⎞}
where E_LOST is the energy lost in charging and discharging Cp in the sustain circuit without
energy recovery.
It is worth noting that the recovery efficiency is not the same as the conventional power
efficiency defined in terms of the power delivered to a load, since no power is delivered to
the capacitor Cp. It is simply charged and then discharged. The recovery efficiency is a
measure of the energy loss in the sustainer, and could reach a value higher than 90%.
Summarizing, the panel's pixels are connected in parallel and can be represented as an
equivalent panel capacitor Cp. A proper switching sequence, together with the energy
recovery circuit, allows this circuit to produce an AC voltage required to illuminate, recover
residual energy and reset the cells of the panel.
Referring to the schematic in Figure 12, Power devices in the Sustain circuit topology can be
grouped into four circuit sub-functions:
1. Energy recovery circuit (ERC) which consists of T1, T2, T11, T12, D1, D2, D3, D4, D5,
D6, D7, D8
2. Sustain circuit (discharge circuit or sustainer) which consists of T3, T4, T9, T10
3. Path circuit which consists of T5, T6
4. Set and Reset circuit which consists of T7, T8
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