The power booster unit: T3STERBOOST

Figure 7-7: Schematic diagram of T3Ster-Booster connections in R-switch mode

General description

T3Ster-Booster is an add-on option of T3Ster. It is an extension unit designed to raise the switched power driving capability of the T3Ster equipment up to 1000W or 20A. The booster unit consists of two separate parts: the Current booster and the R-driver booster. Both units enhance the driving or switching capability of the T3Ster Main System Unit by a factor of ten. The figure of merit value (defined as max. switched power / temperature resolution) is approximately 100,000 W/^oC with the booster.

The main modes of operation are as follows:

1. Diode measurement

In this mode both the dissipating element and the temperature sensor are the same large pn junction. A typical application is measuring general purpose ICs where only the substrate diode can be used for thermal transient recording. The maximum switched current is 20A, the switched power is typically 20-26W in this case. This measurement is supported by the Current booster side of the booster unit.

2. Measurement with resistor dissipator

In this mode the dissipator element is a large-sized resistor. Either pn junctions or temperature-sensitive resistors can be used as temperature sensors. A typical application is measuring dedicated thermal test chips. The switched power can be as large as 1000W (maximum 50V, maximum 20A. This mode of operation is supported by the R-driver booster side of the booster unit.

3. Auxiliary mode:

This mode allows measurement of npn bipolar transistors. Up to U_CB = 50V and I_E = 20A can be applied, the maximum switched power is 1000W. This measuring arrangement can be built by using the Current booster side of the booster unit.

Detailed specification

The T3Ster-Booster is an extension unit of the T3Ster Main System Unit. Control is ensured through appropriate control outputs of the Main System Unit.

The booster unit requires an external power supply unit.

The Current booster side

This unit multiplies the I_E+ current provided by the T3Ster Main System Unit by a factor of ten.

• The current can be programmed in software as in the case of the Main System Unit operation. The current value is programmable between the limits of 1A and 20A.
• The current source can drive pn diodes up to a forward voltage of 1.4V.
• The current is switched on/off by the control software. The switching transient is shorter than 1µs at switching off and shorter than 6µs at switching on.
• The forward voltage of the DUT diode is measured back by the T3Ster Main System Unit. The true dissipation step is automatically recorded and used during the evaluation.
• The polarity of the DUT pn junction is definitive: the p side has to be connected to the ground.
• The powering of the current booster unit has to be provided by an external dc supply, with U_EXT=5±0.2V, I>21A capability. (A power supply with lower current driving capability can also be accepted, in this case, of course, the maximum current through the device will be the current limit of the dc supply minus 1A.)

Figure 7-8: Simplified schematic of the Current booster side of the booster unit

The connections of the Current booster side of the booster unit are the following:

• DUT+ and DUT- (two connectors to the diode)
• Uext+ and Uext- (two connectors to the external supply unit)
• 9 pin female D-Cannon plug (for cable to the JP1 socket on the Power-switch and Thermostat Driver module of the T3Ster Main System Unit - see section 5.3)
• BNC connector (to the IE+ input of the TRNDR transistor driver unit of the T3Ster Main System Unit - see section 5.1)

The R-switch booster side

In R-switch mode the booster acts as a very fast high-power electronic switch.

• The maximum value of the switched voltage is U_max=50V, while the maximum switched current is I_max=20A. This means that the maximum switched power is 50Vx20A =1000W. This maximum can be exploited if the resistance of the dissipator is 50V/2 A = 2.5 Ohm.
  
  For example, if the resistance of the dissipator is 5 Ohm, the current is only 10 A and the applied power is 500 W, etc.
  
  
• The current is switched on/off by the control software. The switching transient is shorter than 1µs at switching on and 2µs at switching off.
• The current and the voltage drop of the dissipator is measured back by the T3Ster Main System Unit. The true dissipation step is automatically recorded and used during the evaluation.
• The powering of the R-switch booster unit has to be provided by an external dc supply, with U_EXT = 1…50V, I > 20A capability. (Power supply with lower current driving capability can also be accepted, the current requirement is I = U_EXT/R_DISSIPATOR.)

Figure 7-9: Simplified schematic of the R-switch booster side of the booster unit

The connections of the R-switch side of the booster unit are the following:

• RL+ and RL- (two connectors to the heater resistor)
• Sense+ and Sense- (two connectors from the heater resistor)
• Uext+ and Uext - (two connectors to the external supply unit)
• 15 pin female D-Cannon plug (for the cable to the JP1 socket on the Power-switch and Thermostat Driver module of the T3Ster Main System Unit - see section 5.3)

In case an exact measurement of the powering is required a four wire connection of the heater resistor is proposed as shown in Figure 7-9. If the sense wires are omitted the R-switch booster measures automatically the voltage of the force pins through the 100 W resistors of Figure 7-9 (gray).

The T3Ster Measurement Control & Evaluation Tool provides graphical help to establish the proper connections between the T3Ster Main System Unit, the power-booster unit, the external DC supply and the device under test (DUT), like in Figure 7-10.

For more details on measurement with the booster equipment consult section 6.3 of the T3Ster Measurement Control Reference Guide.

Note, that the booster options of the T3Ster software are licensed only if a booster equipment is purchased.

Figure 7-10: Help window in the measurement control software (diode measurement with the current booster).