AN2503 Application note PDP Power Devices Introduction This application note discusses how to select optimal power devices and control circuitry for alternating plasma display panel applications, concentrating on power circuits used to sustain plasma discharge on the panel. Plasma Display Panels (PDP) are emerging as the leading candidate for large area wallhanging color TVs and HDTVs [1.]. Its large screen, wide viewing angle, and thinness have given it the edge over conventional displays. Scan, Energy Recovery (ERC) and Sustain (discharge) circuits are important blocks that fulfill important energy saving requirements. May 2007 Rev 1 1/30 www.st.com Contents AN2503 Contents 1 PDP Module structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2 PDP basic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3 2.1 PDP cell structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.2 Panel memory characteristic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.3 PDP driving sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 PDP Sustain circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 3.1 4 Sustain circuit operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 3.1.1 Positive pulse of Vyx . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 3.1.2 Positive discharge and clamping phase . . . . . . . . . . . . . . . . . . . . . . . . . 13 3.1.3 Vyx back to zero . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 3.1.4 Clamping to ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 3.2 Symmetrical Y - X phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 3.3 Reset phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 PDP Power Devices characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 4.1 Power devices from ST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 4.1.1 Measurement set-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 4.1.2 Energy recovery section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 4.1.3 Discharge section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 4.1.4 Path section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 4.1.5 Set - reset section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 4.2 Driving section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 4.3 Gate driver devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 4.3.1 4.4 Totem pole . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Input buffer section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 5 Bill of material and schematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 6 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 7 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 8 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 2/30 AN2503 List of figures List of figures Figure 1. Figure 2. Figure 3. Figure 4. Figure 5. Figure 6. Figure 7. Figure 8. Figure 9. Figure 10. Figure 11. Figure 12. Figure 13. Figure 14. Figure 15. Figure 16. Figure 17. Figure 18. Figure 19. Figure 20. Figure 21. Figure 22. Figure 23. Figure 24. Figure 25. Figure 26. Figure 27. Figure 28. PDP module structure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Cell structure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Memory effect - no charges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Memory effect - address phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Memory effect - Wall charges deposit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Memory effect - discharge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Memory effect - wall charges deposit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Memory effect - discharge with reverse polarity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Subfield structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Subfield structure – expression of gray level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Sustain circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Circuit scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Circuit scheme – positive pulse of Vyx . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Equivalent circuit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Circuit scheme – positive discharge and clamping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Circuit scheme – Vyx back to zero . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Circuit scheme – clamping to ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Circuit scheme – negative pulse of Vyx . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Circuit scheme – negative discharge and clamping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Circuit scheme – Vyx back to zero . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Circuit scheme – clamping to ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Circuit scheme – set and reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Inductor current. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Gate driver topology with L6385 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Gate driver topology – L6388 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 STS01DTP06 Totem pole. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Board schematic 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Board schematic 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 3/30 PDP Module structure 1 AN2503 PDP Module structure Power supply, address buffer, logic and scan buffer boards are the fundamental blocks of a PDP. In particular, the energy recovery and sustain function are performed by the Y and X drive boards. Power MOSFETs, IGBTs, Diodes and Drivers are key products for ERC and sustain both in X and in Y drive boards. These products are also used for the path, set-reset function in the Y drive board only. Path switches are mandatory to isolate ERC and Sustain switches from the negative voltage applied to the display during the scan phase, while, set and reset switches determine identical initial condition of the plasma cells before each address cycle. Figure 1. PDP module structure ST's extensive portfolio covers the whole solution for an energy recovery circuit (ERC), sustain circuit, path circuit, and set-reset circuit, both from a power device and IC driver perspective. The ST solution takes into account all fundamental requirements like cost, component count, reliability and power consumption. Reduced power losses and higher switching frequency are the main benefits of ST's advanced technology. 4/30 AN2503 2 PDP basic PDP basic Basic knowledge on Plasma Display Panel encompasses manufacturing issues in cell structure, physics principle in the memory effect, and display algorithms needed to create a range of colors. 2.1 PDP cell structure Figure 2 shows the structure of a plasma display glass panel, [2.]. Figure 2. Cell structure An AC PDP display is composed of front and rear glass substrates sandwiched together and then sealed. The air is vacuumed out and a mixture of inert gases (Ne and Xe) is injected between the glass substrates. The separation between the two opposing substrates is about 100um and the space between them is filled with a gas mixture of Ne and Xe. The front glass substrate has a first electrode (X electrode) and a second electrode (Y electrode) which operate as sustain electrodes. The X and Y electrodes are coated with bus electrodes, dielectric layer, and MgO layer in sequence. The MgO protects the dielectric from plasma damage and also aids the plasma in sustaining a discharge through secondary electron emission from its surface. In addition, equivalent capacitor exists between the X and Y electrodes. On the surface of the rear glass substrate, as opposed to the front glass substrate, a third electrode operating as an address electrode (A electrode) is formed to be orthogonal to the X and Y electrodes. Electrically, the entire assembly can now be considered as a three-electrode capacitor. A cross point is formed where the X, Y and A electrodes meet. Three adjacent red, blue and green cross points form a color picture element (pixel) of the panel. In operation, an AC voltage sufficiently high will ionize the gas to create the plasma. Then, the ultraviolet light from the plasma excites the phosphor to create the color image. Each pixel can be independently controlled and can assume different color gradations. The number of pixels available determines the resolution of the glass panel vertically and horizontally. 5/30 PDP basic 2.2 AN2503 Panel memory characteristic The AC PDPs provide inherent memory characteristics [3.], [4.], as explained in the following figures. In general, the AC sustain square pulse voltage (Vxy), whose voltage Vs is smaller than the gas breakdown voltage Vbd, cannot initiate a discharge, as shown in Figure 3. Figure 3. Memory effect - no charges X = Vs Y = GND Address = Vs/2 3 If data pulses Vd are applied to the address electrodes, while scan pulses -Vy are sequentially applied to each Y electrode, the voltage (Vd + Vy) is higher than Vbd and a weak discharge ignites, as shown in Figure 4. Figure 4. Memory effect - address phase X = Vk Y = -Vy Address = Vd 3 Charges, called wall charges (or wall voltage Vw), deposit on the dielectric layer and reduce the effective voltage across the gap. Then, the discharge ceases after a short time, as shown in Figure 5. Figure 5. Memory effect - Wall charges deposit X = Vk Y = -Vy Address = Vd 6/30 AN2503 PDP basic When the polarity of the sustain pulse is reversed, the potential difference across the gap becomes larger than Vbd by an amount determined by the wall charges, and a new large discharge of different polarity occurs, as shown in Figure 6. Figure 6. Memory effect - discharge X = GND Y = Vs Address = Vs/2 The build-up of wall charges again terminates the discharge, as shown in Figure 7. Figure 7. Memory effect - wall charges deposit X = GND Y = Vs Address = Vs/2 3 The next discharge starts as the polarity of the sustain pulse is reversed, as shown in Figure 8. Figure 8. Memory effect - discharge with reverse polarity X = Vs Y = GND Address = Vs/2 Once the discharge is initiated, it continues as long as the sustain pulse is applied. Due to this memory characteristic of AC PDPs, lower sustain voltage (< Vbd) pulses can maintain the ac PDPs to light. In other words, the process of panel image displaying depends on a former process of panel addressing. In fact, during the address phase a small amount of charges (wall charges) deposit on the selected electrodes without any visible light emission. This reduces the 7/30 PDP basic AN2503 threshold voltage for discharge, and consequently, during sustain phase only selected cells ignite and emit light. 2.3 PDP driving sequence The most common method of displaying one picture field is using the Address DisplaySeparation method (ASD). All X electrodes are bused together and connected to a sustain driver, while the Y electrodes are connected to sustain driver through several scan ICs. One TV field is divided into 10 subfields (SFs) in a 10-bit codification case, and each consists of a reset period, an address period, and a display period (Figure 9). On every subfield, each cell is addressed, sustained and erased. Figure 9. Subfield structure During the reset period a slow ramping positive voltage up to 400 V followed by slow ramping negative voltage down to -150 V is applied across the X and Y electrodes to put out ionization and to set an identical initial condition for all the panel cells. In the address period, the Y electrodes receive scan pulses, along with data pulses on the address electrodes, in order to control wall charges in appropriate cells according to the image to be displayed. Note that reset period and address period have the same duration in each subfield, only the number of sustain pulses varies among different subfields. During sustain period, selected cells are sustained in order to display the whole image on the panel. Gray scales are expressed by using the binary-coded light-emission-period method. The display periods are filled with trains of constant width and constant period pulses, and their lengths are arranged according to the binary sequence, 1: 2: 4: 8: 16: 32: 64: 128: 256: 512. Therefore, gray levels of 210 for each color (R, G, and B) can be expressed with an 10-bit sequence. This means that each color element has 1024 color possible graduations and each pixel has 1024 x 1024 x 1024 = 1 billion colors. Figure 10 shows a simplified 8-bit system with 8 subfields. The subfields are weighted according to their binary values and a typical TV field is 1/50 of a second. 8/30 AN2503 PDP Sustain circuit Figure 10. Subfield structure – expression of gray level 3 PDP Sustain circuit In a Plasma Display Panel, frequent discharges are made to occur by alternately charging each side of the panel to a critical voltage, allowing images to be displayed. This alternating voltage is called the sustain voltage, and the sustain circuit (or sustainer) is needed to provide it to the display [5.]. If a pixel has been driven "ON" during address period, the sustainer maintains the "ON" state of that pixel by repeatedly discharging that pixel cell during the whole sustain period. If a pixel has been driven "OFF" by an address driver, the voltage across the cell is never high enough to cause a discharge, and the cell remains "OFF" during the sustain period. The sustain circuit must drive all panel pixels at once. This means that the capacitance as seen by the sustainer is typically very large. In a 42-inch panel with 852x480 pixels, the total capacitance of all the pixel cells, Cp, could be as much as 80 nF. The key parameters in the sustainer study are: ● Cp - Panel equivalent capacitance ● Vs - Sustain Voltage ● f - Sustainer Switching frequency ● fav - average sustainer switching frequency Conventional sustain circuit (half bridge topology) drives the panel directly, and thus 1/2CPVS2 fav is dissipated in the sustainer when the panel is subsequently discharged to ground. In a complete sustain cycle, each side of the panel is charged to Vs and subsequently discharged to ground. Therefore, a total of 2CpVs2 fav power is dissipated in a complete sustain cycle. 9/30 PDP Sustain circuit AN2503 Conventional sustain circuit (half bridge topology) drives the panel directly, and thus 1/2CPVS2 fav is dissipated in the sustainer when the panel is subsequently discharged to ground. In a complete sustain cycle, each side of the panel is charged to Vs and subsequently discharged to ground. Therefore, a total of 2CPVS2 fav is dissipated in a complete sustain cycle. Figure 11. Sustain circuit The power dissipation in the sustainer is then 2CPVS2 fav, where fav is the average sustain cycle frequency. For Cp=80 nF, Vs =200 V, and fav = 100 kHz, the power dissipation in the sustainer, resulting from driving the capacitance of the panel, could be as high as 640 W. If an inductor is placed in series with the panel, then Cp can be charged and discharged through the inductor. This would ideally result in zero power dissipation since the inductor would store all of the energy otherwise lost in the output resistance of the sustainer and transfer it to or from Cp. However, switching devices are needed to control the flow of energy to and from the inductor, as Cp is charged and discharged, respectively, and this leads to power losses. The "ON" resistance, output capacitance, and switching transition time are characteristics of these switching devices that can result in significant energy loss. The amount of energy that is actually lost due to these characteristics, and hence the efficiency, is determined largely by how well the circuit is designed to minimize these losses. In addition to charging and discharging Cp, the sustainer must also supply the large gas discharge current for the plasma panel. This current, I, is proportional to the number of pixels that are "ON" in the same TV frame. The resulting instantaneous power dissipation is I2R, where R is the output resistance of the sustainer. Thus, the power dissipation due to the discharge current is proportional to I2, or the square of the number of pixels that are simultaneously "ON". There are two ways to minimize this dissipation. The first is to reduce the output resistance of the sustainer by using very low resistance output drivers, and the second is to minimize the number of pixels that are "ON" at any time. The switching power losses due to the panel capacitance during sustain period in AC PDP driving system can be minimized using a specific energy recovery circuit. The most common sustain/energy recovery circuit topology refers to Weber topology (Figure 12). 10/30 AN2503 PDP Sustain circuit Figure 12. Circuit scheme Vset T3 Vs T7 D2 D3 T2 L1 T6 T5 T1 X-Electrode Vs Y-Electrode Vs T9 D8 D5 T11 L7 Cp CS1 Vs D1 D4 T12 CS2 D7 T4 T10 D6 T8 -Vreset 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 to Vs and then discharged to zero, the energy that flows into and out of Cp is E = C P V S 2. The recovery efficiency is defined by: Equation 1 2 C P V S – E LOST ⎛ E LOST ⎞ - = 100 • ⎜ 1 – ----------------Eff = 100 • ----------------------------------------⎟ 2 2 ⎝ CP VS CP VS ⎠ where ELOST 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 11/30 PDP Sustain circuit 3.1 AN2503 Sustain circuit operations Sustain circuit operations describe the way to generate a square waveform on the panel capacitor. This section describes how to charge and discharge the panel capacitor in order to perform the sustain phase. 3.1.1 Positive pulse of Vyx After the reset period, we can suppose that all cells on the panel have been already addressed during the address period. This means that the cells to be displayed have accumulated enough wall charge to be ignited, due to cell memory effect. We can assume also that CS1 and CS2 have already their steady state voltage value, this means they have initial voltage of Vs/2 from previous sustain cycles. In order to produce a positive voltage across the panel (Vyx positive), T1, T5, T6 and T10 are turned ON and D1 is forward biased. CS1 charges and raises the voltage across the panel capacitor Cp in a resonant way. This step is a part of the energy recovery phase since it recovers the energy stored in the capacitor CS1 from previous sustain cycles back to the panel. Figure 13. Circuit scheme – positive pulse of Vyx Vset T3 Vs T7 D2 D3 T2 L1 T6 T5 T1 X-Electrode Vs Y-Electrode Vs T9 D8 D5 T11 L7 Cp CS1 Vs D1 T12 CS2 D7 D4 T4 T10 D6 T8 -Vreset The equivalent circuit during the LC resonant period of the energy recovery circuit is: Figure 14. Equivalent circuit In Figure 14, R represents the parasitic resistance including on-resistances of switches and VON represents the diode forward drop. Based on this figure, the panel voltage Vyx can be obtained as follows: Equation 2 – --t- V R τ V yx = ⎛ -----s- – V ON⎞ 1 – e ⎛ cos ωt + ------ sin ωt⎞ ⎝2 ⎠ ⎝ ⎠ ωL 12/30 AN2503 PDP Sustain circuit ωR Where τ = ⎛⎝ -------⎞⎠ L 1 ⎞ ⎛ R ⎞2 ⎛ ---------- – ------⎝ LCp⎠ ⎝ 2L⎠ ω= and If (2L/R)2 and (ωR/L) can be ignored, the equation (Equation 2) can be simply re-written as: Equation 3 t --- V τ V yx = ⎛ -----s- – V ON⎞ 1 – e cos ωt ⎝2 ⎠ Where ω’ = 1---------LCp If ω’ = ∏ then the peak value is: Equation 4 V yx, pk V = ⎛⎝ -----s- – V ON⎞⎠ 1 – e 2 πR C – ------- ------p 2 L Equation 4 states that an increase of the parasitic resistance causes the recovery efficiency to be degraded. Naturally, it is necessary to reduce the parasitic resistance by designing the circuit board optimally as well as choosing switching devices with small on-resistance and low on-drop voltage to minimize the hard-switching stress and improve the recovery performance. On the other hand, reduction of the inductor value produces similar results and, thus, using a too small value of L is not desirable with respect to driving loss. Positive discharge and clamping phase Figure 15 shows both panel discharge and the camping current paths. In the first phase the ionized gas could be represented as a non linear resistor and the peak current during this period is higher than that during energy recovery. The worst condition is represented when all cells in the panel must be ignited (full white screen condition), and in this case the discharge current could be higher than 120 A for a standard definition (SD) 42-inch PDP set. Further increase in the current value is expected in HD PDP as the number of pixels increases. Figure 15. Circuit scheme – positive discharge and clamping Vs Vset T3 Vs T7 D2 D3 T2 L1 T6 T5 T1 X-Electrode Vs Y-Electrode 3.1.2 T9 D8 D5 T11 L7 Cp CS1 D1 D4 Vs T12 CS2 D7 T4 T10 D6 T8 -Vreset 13/30 PDP Sustain circuit AN2503 The discharge current has also a sinusoidal profile, and is conducted by T3, T6, T5, Cp, and T10. Once the panel is charged to Vs and visible light is emitted, current stops flowing and the gas inside the glass stops ionizing. (Note that the use of IGBTs in the discharge section requires extra care; indeed power devices requires freewheeling diodes to carry reverse current due to the tank circuit formed between the panel capacitor Cp, L1 and the bus capacitance). At this time D1 is reverse biased and its reverse current charges the inductance L1. The energy stored in the inductance is removed through the clamping current, and the clamping current path is carried out by T3, D3, and D2. In this phase the reverse current of D1 is a key parameter in power loss reduction. In fact, a lower clamping current means lower conduction losses in T3, D2 and D3. Depending on the topology used, and in particular the clamping diode's position, the time spent to evacuate the energy stored in the inductance can vary significantly. 3.1.3 Vyx back to zero The next phase consists of bringing back to zero the panel capacitor voltage and reverse the polarity of the voltage across Y-X electrodes. In order to efficiently decrease the voltage on the panel capacitor, the energy stored in Cp could be recovered back in the recovery capacitor CS1.This can be done by turning ON T2, T6, T5, and T10. The current path is shown in Figure 16. This current stops flowing when the voltage across the panel capacitance Vyx and CS1 reach the same value (Vs/2). The profile of this current is half sinusoidal and its direction is from the panel Cp back to CS1. Figure 16. Circuit scheme – Vyx back to zero Vset T3 Vs T7 D2 D3 T2 L1 T6 T5 T1 X-Electrode Vs Y-Electrode Vs T9 D8 D5 T11 L7 Cp CS1 D1 D4 Vs T12 CS2 D7 T4 T10 D6 T8 -Vreset 3.1.4 Clamping to ground In order to bring completely to zero the panel capacitance, T10, T5, T6, and T4 are turned ON, creating a current path across the panel through the equivalent resistances of power devices and parasitic elements of the circuit. 14/30 AN2503 PDP Sustain circuit Figure 17. Circuit scheme – clamping to ground Vset T3 Vs T7 D2 D3 T2 L1 T6 T5 T1 X-Electrode Vs Y-Electrode Vs T9 D8 D5 T11 L7 Cp CS1 Vs D1 T12 CS2 D7 D4 T4 T10 D6 T8 -Vreset Symmetrical Y - X phase A similar switching sequence is applied in order to reverse the polarity across Y-X electrodes (X electrode more positive than Y electrode) In particular, this can be briefly described as: a) Energy recovery, path and discharge switches, T12, T5, T6, and T4 are turned ON, and the current flows from CS2 to Cp. Figure 18. Circuit scheme – negative pulse of Vyx Vset T3 Vs T7 D2 D3 T2 L1 T6 T5 T1 X-Electrode Vs Y-Electrode Vs CS1 Vs T9 D8 D5 T11 L7 Cp D1 T12 CS2 D7 D4 T4 T10 D6 T8 -Vreset b) Discharge and Clamp phases: T9, T4, T5, T6 are turned ON and the current flows from Vs to Cp and through T9, L7, D7, D8. Figure 19. Circuit scheme – negative discharge and clamping Vs Vset T3 Vs T7 D2 D3 T2 L1 T6 T5 T1 X-Electrode Vs Y-Electrode 3.2 T9 D8 D5 T11 L7 Cp CS1 D1 D4 Vs T12 CS2 D7 T4 T10 D6 T8 -Vreset 15/30 PDP Sustain circuit AN2503 c) Energy Recovery phase: T4, T5, T6, and T11 are turned ON, and the current flows from Cp to CS2. Figure 20. Circuit scheme – Vyx back to zero Vset T3 Vs T7 D2 D3 T2 L1 T6 T5 T1 X-Electrode Vs Y-Electrode Vs T9 D8 D5 T11 L7 Cp CS1 Vs D1 T12 CS2 D7 D4 T4 T10 D6 T8 -Vreset d) Zero voltage Clamp, T4, T5, T6, T10 are turned ON. Figure 21. Circuit scheme – clamping to ground V V Vse T V T V T D D D T L CS D T Y -T E l e c X-Electrode D T1 L C T1 CS D T1 D T It can be noted that during sustain phase, path switches T5 and T6 are always turned ON, and they see both energy recovery current and discharge current which explains the need for low voltage drop devices. 3.3 Reset phase At the end of each subfield, the cells are reset applying a positive ramp voltage followed by a negative one. During positive reset, T10, T5, T7 are turned ON. During negative reset T10 and T8 are turned ON. 16/30 AN2503 PDP Power Devices characteristics Figure 22. Circuit scheme – set and reset Vset T3 Vs T7 D2 D3 T2 L1 T6 T5 T1 X-Electrode Vs Y-Electrode Vs Vs T9 D8 D5 T11 L7 Cp T12 C S2 C S1 D1 D4 D7 T4 T10 D6 T8 -Vres et 4 PDP Power Devices characteristics A clear idea of circuit operation will help us to highlight the main features of the devices involved. In particular the analysis can be split in power devices analysis and driving devices analysis, in order to address specific characteristics of each device. 4.1 Power devices from ST Power devices in PDP have common characteristics that range from high peak current capability and low forward voltage drop to fast turn-ON capability. The current both in the Energy Recovery Circuit (ERC) and in the Discharge Circuit (DC) follows a half sinusoidal pattern. ERC and DC could be simply classified as soft switching converters. In fact, the circuit can be considered as a series resonant LCR circuit, so the current at turn-ON is zero (zero current switching) and the voltage at turn-OFF is zero (zero voltage switching). Since a MOSFET has an intrinsic body diode across it, a MOSFET does not require an antiparallel diode when selected as power devices on the discharge circuit, while an IGBT needs a specific freewheeling diode. For ER circuit, the Power Switch does not require an anti-parallel diode since reverse current is blocked by the diodes in series with the devices (D1, D3, D5 and D7), thus MOSFET or IGBT can be used as power devices on the ER circuit. Diodes D2, D4, D6 and D8 provide additional protection clamping the voltage on the inductors avoiding damage to devices on the ER circuit. Path circuit has to carry both ER and Discharge currents, thus it is required to have very low voltage drop. It can be noted that during ER and Discharge cycles, the pass circuit remains on. The Path circuit switches on and off only during reset period which happens at the end of each subfield, which means that the maximum frequency is in the range of 1 kHz. The Path circuit is a bidirectional circuit, so a MOSFET, that can carry current in both directions, could be used for this circuit. ST has a broad range of products covering the power section ranging from MOSFET and IGBT to dedicated Diodes. 17/30 PDP Power Devices characteristics 4.1.1 AN2503 Measurement set-up Power losses and thermal analysis measurements were performed based on an average switching frequency. In fact, switching performances have to be related to the maximum frequency in the system, usually 250 kHz, whereas power losses and thermal management have to be related to an average frequency. The Average Switching frequency takes into account the fact that during a picture time, the power devices do not switch at the maximum frequency for the whole time, but only during the sustain phases. The sustain duration, and consequently the number of sustain pulses, increases starting from subfield 1 to subfield 10. Average frequency can be calculated starting from sustain duty ratio. Table 1. Scan speed VGA 480 XGA 768 HD 1080 3 µsec - - - 2.5 µsec 0.130 - - 2 µsec 0.274 - - 1.5 µsec 0.418 0.159 - 1 µsec 0.562 0.389 0.202 Table 2. Note: 10 subfield / single scan 10 subfield / dual scan Scan speed VGA 480 XGA 768 HD 1080 3 µsec 0.418 0.158 - 2.5 µsec 0.490 0.274 0.040 2 µsec 0.562 0.389 0.202 1.5 µsec 0.634 0.504 0.364 1 µsec 0.706 0.620 0.526 Sustain duty = picture time - reset period x SF - N x SF x scan speed [µs / line] Picture time = 16.67 ms Reset period = 250 µsec SF = number of sustain pulses N = number of lines The sustain duty ratio is carried out for a 10 subfield case in both single scan and dual scan operations, varying the scan speed duration (time needed to scan a single line in the display), for VGA (480 lines), XGA (768 lines) and HD (1080 lines). According to the following formula, fav=fswitching x SustainDuty For a VGA display →SustainDuty = 0.27 ÷ 0.56 →fav = 68 ÷ 140 kHz This means that power devices in ERC and discharge circuit need to be designed for an average frequency of 140 kHz (maximum) in terms of power losses and thermal management. Clearly peak current and peak voltage rating do not change when we perform this averaged analysis. 18/30 AN2503 PDP Power Devices characteristics Typical voltage requirements for a PDP are: 4.1.2 ● Sustain voltage Vs = 200 V ● Set voltage Vset= 400 V ● Reset voltage Vreset= -150 V Energy recovery section For Energy recovery circuit, the maximum voltage stress is Vs/2 ≈ 100 V, and the current stress depends on the device. The clamping diodes have to withstand a current lower than 10 A, whilst the ERC switches and the ERC diodes have to be able to handle a resonant half-sinusoidal current up to 100 A peak. The typical current waveform in the Energy recovery circuit is shown in Figure 23. The key parameters of the DERC diode for the energy recovery circuit have been optimized in order to decrease power losses. Figure 23. Inductor current ER C current T1 C lam ping current T3 D2 D3 For ER circuit new devices with low voltage drop and very fast turn ON have been developed. ● Energy recovery diodes STTH60P03, STTH40P03 Energy recovery diodes (D1, D3, D5, and D7) have been tailored on this application optimizing key parameters to reduce power losses [6.], [7.]. They have the ability to handle large repetitive peak current (Irp), in conjunction with a lower reverse current (IRM) and peak forward voltage (VFP). Table 3. Symbol STTH60P03 Features Parameter Test conditions IRM Reverse recovery current T = 100°C j Sfactor Softness factor VFP Peak forward voltage Tj = 25°C IF = 60 A VR = 100 V dIF/dt = 200 A/µs IF = 60 A dIF/dt = 400 A/µs Min. Typ Max. Unit 6 7.5 A 3.5 V 0.5 2.5 19/30 PDP Power Devices characteristics ● AN2503 Clamping diodes STTH2003, STTH1003 Diodes D2, D4, D6, and D8 provide additional protection to clamp the voltage on the inductors [8], [9]. Overvoltage is due to ER diodes reverse current that store energy in the inductors. The fact that reverse current IRM of ERC diodes stores energy in the inductors (and can cause overvoltage if we do not use clamping diodes D2, D4, D6, and D8), demonstrates that the IRM in ERC diodes is a key parameter to take into account. In fact, IRM causes power losses both in Clamping diodes and Discharge switches. Table 4. Clamping diodes features P/N IF [A] VRRM [V] Trr [ns] Tj[C] VF[V] Package STTH1003 10 300 13 175 0.9 DPAK, TO-220FP, D2PAK STTH2003 2x10 300 35 175 1 DPAK, TO-220FP, D2PAK, TO220 ● Energy recovery MOSFET ST75N20 T1, T2, T11, and T12 are the power switches used in the Energy recovery circuit. Due to the reactive nature of the load, the voltage across the power switch falls rapidly followed by a rapid rise in the current. This explains why a fast turn-ON is needed, and low conduction losses (low drop) can be achieved only reducing the RDSON. The STW75N20 Power MOSFET in proprietary STripFETTM technology, thanks to its low RDSON and low gate charge is perfectly tailored for the application [9.]. Table 5. 4.1.3 ERC MOSFET features P/N VDSS [V] RDSON[Ω] ID/IDMAX [A] P [W] Package ST75N20 200 0.028 75/300 300 TO-247, TO-220, D2PAK Discharge section When the panel discharges, a sinusoidal shaped current will go through the discharge switches. The current could reach a peak value higher than 120 A in worst condition (full white screen), thus low RDSON and fast turn-ON are required. Maximum voltage stress for discharge circuit is Vs = 200 V ● Discharge MOSFET STW52NK25Z The STW52NK25Z Power MOSFET in property superMESHTM technology, and due to its low RDSON and low gate charge is perfectly tailored on the application [10.]. Table 6. 4.1.4 Sustain MOSFET features P/N VDSS [V] RDSON[Ω] ID/IDMAX [A] P [W] Package P/N STW52NK25Z 250 0.033 52/208 300 TO-247 STW52NK25Z STW54NK30Z 300 0.060 54/200 300 TO-247 STW54NK30Z Path section For Path circuit, MOSFET is the preferred device since this circuit is required to conduct current in both directions. The switching frequency is low, and the RMS current through this 20/30 AN2503 PDP Power Devices characteristics circuit is very large since it has to conduct both ER and discharge currents. Both STripFETTM and superMESHTM Power MOSFETs technologies from ST are ideal for this application since they allow the die to have very high current density and therefore reduce the number of paralleled devices required to maintain very low voltage drop [9.], [10.], [11.], [12.]. For path switch in T6 position, the maximum voltage stress is (Vs + Vset) / 2 ≈ 300 V, while for path switch in T5 position, the maximum voltage stress is (Vset + |Vreset|) / 2 ≈ 275 V. Table 7. 4.1.5 Path MOSFET features P/N VDSS [V] RDSON[Ω] ID/IDMAX [A] P [W] Package ST60NK30ZD1 300 0.045 60/240 450 Die or MAX247 STW52NK25Z 250 0.033 52/208 300 TO-247 ST75N20 200 0.028 75/300 300 TO-247, TO-220, D2PAK ST40N20 200 0.045 40/160 160 TO-247 TO-220 D2PAK TO220FP Set - reset section The set and reset circuit applies asymmetrical AC voltage across the panel in order to evacuate any remaining surface charge from the cells. This is usually done at the end of each subfield (or the beginning of the next subfield), and the power devices on this circuit operate in the linear mode. This means that the voltage drop is very large but the current through the device is relatively low. Due to the requirement of asymmetrical Set and Reset voltages, Power switches in the set and reset circuits have to block up to 600 V. Typical voltage value for Set function is 400 V and for Reset function is -150 V. This means that the maximum voltage stress for Set circuit T9 is (Vs + Vset) = 600 V while the maximum voltage stress for reset circuit T10 is Vset + |Vreset| = 550 V. ST offers two families of products for this section both appreciable for their ruggedness for linear applications. Example device is STGP10NB60S in the IGBT Planar technology [13.]: Table 8. Set – reset IGBT features P/N VCES [V] VCE(SAT)[Ω] IC [A] Package STGP10NB60S 600 1.7 10 D2PAK Further examples of devices are superMESHTM devices as follows [14.], [15.]. Table 9. Set-reset MOSFET features P/N VDSS [V] RDSON[Ω] ID/IDMAX [A] P [W] Package ST9NK70Z 700 1 7.5/30 115 W TO-220 D2PAK TO220FP ST14NK60Z 600 0.5 13.5/54 160 W TO-220 D2PAK TO220FP 21/30 PDP Power Devices characteristics 4.2 AN2503 Driving section Driving section devices range from gate driver devices to input buffer ones. Gate driver function is carried out by a gate driver IC and a push pull amplifier. Driving section can be split in: 4.3 ● Gate driver section: L6385 or L6388 ● Push pull section: STS01DTP06 ● Input buffer section 74VHCT541 Gate driver devices ST offers the widest series among the High Voltage Half-Bridge Gate Drivers (the L638x series), manufactured with BCD"OFF-LINE" technology. They are able to work in applications with with voltages to 600 V. In the L638x series the two selected drivers are the L6388 [16.] and the L6385 [17.], which can drive two Power MOSFETs or IGBTs, one highside and one low-side, in a Half-Bridge or different topology. L6388 is especially effective in applications where logic input must be compatible with 3.3 V Logic. Another key feature of the L6388 is that it provides effective anti-shoot-through circuitry which prevents two Power MOSFETs or IGBTs from being turned ON at the same time. This is achieved by introducing a 200 ns time interval, a "dead time" between the moment one of the components is turned OFF and the other is turned ON. L6385 is able to drive asymmetrical half bridge, but its logic input is not compatible with 3.3V Logic. The main features of these HV Gate Drivers are: ● dV/dt immunity +- 50 V/nsec in full temperature range ● Driver current capability: – 400 mA source – 650 mA sink ● Switching time 50/30 nsec rise/fall with 1 nF load ● Under voltage lock-out on lower and upper driving section ● Internal bootstrap diode ● Outputs in phase with inputs Due to different characteristics, the topologies used in Energy Recovery Circuit and Sustain Circuit depend on the driver used as shown in Figure 24 and Figure 25. 22/30 AN2503 PDP Power Devices characteristics Figure 24. Gate driver topology with L6385 L638x 1 2 3 VCC 4 LIN Vboot HIN HVG Vcc OUT GND 8 PP 7 Vs 6 5 LVG Vs VCC PP TO PLASMA Vs/2 L638x 1 LIN Vboot HIN HVG Vcc OUT GND LVG 2 3 VCC 4 8 PP 7 6 5 VCC PP Figure 25. Gate driver topology – L6388 p gy Vs Vs L638x 1 2 VCC 3 4 LIN Vboot HIN HVG Vcc OUT GND LVG 8 PP 7 6 5 Vs/2 VCC TO PLASMA PP L638x 1 2 VCC 3 4 LIN Vboot HIN HVG Vcc OUT GND LVG 8 PP 7 6 5 VCC PP Due to current value in bootstrap charge, the internal diode cannot be used, thus external diode SMBY01-400 [20.] must be used. Further details on L6585 and L6588 application can be found in [18.] and [19.]. 4.3.1 Totem pole In order to match inherent power devices characteristics, (as high gate charge) with drivers current capability, totem pole STS01DTP06 [21.] in a push pull configuration is used in the application. The STS01DTP06 is housed in the SMD dual island SO-8 package and allows an optimized electronic solutions, by improving circuit efficiency, saving space and reducing component count on the board. The STS01DTP06 is a hybrid complementary NPN and PNP bipolar transistor manufactured using the latest low voltage planar technology. Extremely efficient performance is obtained by combining high pulse current, excellent gain and fast speed, 23/30 PDP Power Devices characteristics AN2503 resulting in low losses in high frequency applications. The STS01DTP06 offers a 30 V NPN and PNP combination supporting a continuous collector current of 3 A and the minimum gain of the two transistors is 100 at 1 A collector current. The transistor elements are fully independent so that higher assembly flexibility is guaranteed. Concerning PDPs, this means that the turn-ON and the turn-OFF resistors could be different. Figure 26. STS01DTP06 Totem pole The STS01DTP06 main features are summarized in Table 10: Table 10. STS01DTP06 Features Part number VCEO[V] NPN STS01DTP06 4.4 Ic[A] Ptot[W] hFEmin VCE(sat)@ MAX [V] Ic[A] IB[mA] PNP 30 3 1.6 100 0.7 2 100 Input buffer section The 74VHCT541 is an advanced high-speed CMOS OCTAL BUS BUFFER (3-STATE) fabricated with sub-micron silicon gate and double-layer metal wiring C2MOS technology, available in TSSOP package [22.]. In order to enhance PC board layout, the 74VHCT541 offers a pin-out having inputs and outputs on opposite sides of the package. The device is characterized by high speed and low power dissipation. Power down protection is provided on all inputs and 0 to 7 V can be accepted on inputs with no regard to the supply voltage. This device can be used to interface 5 V to 3 V. All inputs and outputs are equipped with protection circuits against static discharge, giving them 2KV ESD immunity and transient excess voltage. 24/30 AN2503 5 Bill of material and schematics Bill of material and schematics Table 11 gives the BOM and the schematics of the demo board. Table 11. Bill of material Item Qty Reference Value & comment 1 5 C1,C4,C23,C26, C44 2.2 µF 50 V 2 5 C2,C3,C24,C25,C45 100 nF 50 V 3 4 C5,C6, C20,C21 2.2 nF 400 V 4 4 C16,C17,C18,C19 3.3 µF 250 V 5 1 C22 104 K 250 V 6 8 C27,C28,C29,C30,C48,C49,C50,C51 100 µF 250 V 7 2 C35,C36 100 µF 25 V 8 7 C37,C38,C39,C40,C41,C42,C43 100 pF 10 V 9 2 C46,C47 X1 Capacitor modeling the panel 10 4 D1,D7 SMBY01-400 11 2 D2,D10 STTH60P03SW 12 3 D3,D8 STTH2003CG 13 3 D14 DIODE Z.16 V 14 1 F1 5A 250 V Fuse 15 2 F2,F3 1A 125 V 16 1 J1 HEADER 9 17 2 J4,J13 Connector 2 PINS 18 1 J7 GND-STAR Connector 19 1 J18 HEADER 30 20 2 L5,L6 500 nH inductor 21 2 L12,L14 10 µH inductor 22 2 R2,R19 2,2 Ω SMD resistor 23 8 R7,R8,R9,R10,R17,R18,R21,R22 3.9 Ω SMD resistor 24 2 R1, R20 36 Ω SMD resistor 25 5 R35,R36,R37,R38,R39 200 Ω SMD resistor 26 4 R50, R51 100 KΩ SMD resistor 27 6 R3, R4, R23, R24, R25 1 Ω SMD resistor 28 6 R26,R40,R41,R42,R43,R44 100 Ω SMD resistor 29 3 R27 10 KΩ SMD resistor 30 2 U1,U5 L 6385 31 4 U2,U3,U6,U7 STS01DTP06 25/30 VCC VCC LIN U4005 C4 22uF-50V HIN U4004 C3 100nF C26 22uF-50V LIN-U4004 C31 33pF HIN U4005 4 3 2 1 4 3 GND VCC HIN LIN U1 C25 100nF 2 1 U5 LGV VOUT L 6385 LGV VOUT Vboot HGV 5 6 8 7 SMBYT01-400 D1 HGV Vboot L 6385 GND VCC HIN LIN 5 6 8 7 SMBYT01-400 C2 2.2 R2 22uF-50V100nF C1 36 R20 C23 22uF-50V 2.2 R19 B2 B1 B2 B1 4 2 U2 STS01DTP06 4 2 U3 STS01DTP06 4 2 U7 C24 100nF B2 B1 STS01DTP06 36 R1 B2 B1 STS01DTP06 4 2 U6 7 5 8 E2 E1 C1 7 C1 C2 5 C2 6 8 E2 E1 C1 7 C1 C2 5 7 C2 8 E2 E1 C1 C2 VCC 6 C1 C2 6 8 E2 E1 C1 5 C1 C2 26/30 C2 3 1 3 1 3 1 3 1 R4 1 R3 1. R27 10K 104K 250V C22 R8 R7 V sustain/2 D3 U13 3.9 3.9 T12 1 3 U16 K D2 T9 R10 R9 STTH60P03SW A1 A2 T11 K D10 V sustain 3.9 3.9 2 A1 A2 Res IND STTH60P03SW T10 3.9 R21 3.9 STW52NK25Z R22 STW52NK25Z U12 STW75N20 U15 D8 STTH2003CG DIODE Z.16v D14 STW75N20 R24 STTH2003CG 100 R26 1K R25 1 R23 1 R18 3.9 R17 3.9 2 1 J4 CON2 T9 500nH 500nH C16 C21 2.2nF 3.3uF 250v C20 2.2nF C5 C6 2.2nF 400v 2.2nF 400v L6 L5 T10 STW52NK52Z U11 U14 STW52NK25Z C18 C19 Res IND C47 X1 Display 3.3uF 250v 3.3uF 250v 3.3uF 250v C17 C46 X1 Display R51 100K V sustain/2 100K R50 V sustain Table 11. 6 D7 Bill of material and schematics AN2503 Bill of material (continued) Item Qty Reference Value & comment 32 1 U8 74VHCT541 33 4 U11,U12,U14, U16 STW52NK25Z 34 2 U13,U15 STW75N20 35 3 J15, J16, J17 Connector 17 pins Figure 27. Board schematic 1 1 2 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 HEADER 30 J18 GND-STAR J7 1 2 3 4 5 6 7 8 9 HEADER 9 J1 Vb FUSErid F1 FUSErid F2 1K R34 1K R33 1K R32 1K R31 1K R30 100uF250V INDUCTOR L14 10uH L12 C27 VDD C41 100pF C40 100pF C39 100pF C38 100pF C37 100pF C28 C35 100uF 25v C29 C43 100pF Xb Xg Xs Xf Xr C30 Xs Xg Xf Xb Xr 1 2 C50 C42 100pF ENABLE J13 C49 C36 100uF 25v C48 VCC 1 2 3 4 5 6 7 8 9 10 C51 1 2 3 4 5 6 7 8 9 10 U8 20 19 18 17 16 15 14 13 12 11 st74v hct541 C45 100nF FUSErid F3 20 19 18 17 16 15 14 13 12 11 C44 22uF25v VDD V sustain R38 200 R35 200 R36 200 R37 200 R39 200 100 R43 100 R42 100 R41 100 R40 100 R44 HIN U4005 HIN U4008 HIN U4004 LIN-U4004 LIN U4005 Xf Xb Xr Xg Xs Display 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 CONN SOCKET 17 J17 CONN SOCKET 17 J16 CONN SOCKET 17 J15 AN2503 Bill of material and schematics Figure 28. Board schematic 2 27/30 Conclusions 6 AN2503 Conclusions ST offers its customers a complete product portfolio covering the whole PDP. ST's system approach helps customers design effective energy recover (ERC) and Sustain circuits, improving their time-to-market. PDP power consumption is greatly reduced using ST's dedicated products. 7 References 1. "Plasma displays," IEEE Trans. Plasma Sci., vol. 19, pp. 1032-1047, Dec. 1991. 2. "Cell structure and driving method of a 25-in (64 cm) diagonal high-resolution color ac plasma display," in Proc. Symp. Society for Information Display, vol. 29, 1998, pp. 279282. 3. "Charge spreading and its effect on AC plasma panel operating margins," IEEE Trans. Electron Devices, vol. ED-24, pp. 870-872, July 1997. 4. "Measurement of wall charges in a surface discharge AC-PDP," in Proc. Int. Display Workshops, 1997, pp. 527-530. 5. " Power efficient sustain drivers and address drivers for plasma panel," U.S. Patent 4 866 349, Sept. 1989 and U.S. Patent 5 081 400, Jan. 1992. 6. STTH60P03SW Datasheet 7. STTH40P03SW Datasheet 8. STTH2003CG Datasheet 9. STW75N20 Datasheet 10. STW52NK25Z Datasheet 11. STP40N20 Datasheet 12. ST60NK30ZD1 Datasheet 13. STGP10NB60S Datasheet 14. STP9NK70Z Datasheet 15. STB14NK60Z Datasheet 16. L 6388 Datasheet 17. L 6385 Datasheet 18. AN994 - L6384, L6385, L6386, L6387 Application guide 19. AN1299 - L6384, L6385, L6386, L6387: TIPS & TRICKS 20. SMBY01-400 Datasheet 21. STS01DTP06 Datasheet 22. 74VHCT541 Datasheet 28/30 AN2503 8 Revision history Revision history Table 12. Revision history Date Revision 02-May-2007 1 Changes First issue 29/30 AN2503 Please Read Carefully: Information in this document is provided solely in connection with ST products. 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