company blog about Infineon IKW25N120T2 1200V 25A IGBT Transistor With Anti-Parallel Diode

Shenzhen Mingjiada Electronics Co., Ltd. supplies the Infineon IKW25N120T2 1200V 25A IGBT transistor with an anti-parallel diode.

I. IKW25N120T2 Model and Product Positioning

The IKW25N120T2 is a 1200V/25A single-transistor IGBT from Infineon’s second-generation (T2) TRENCHSTOP series. It utilises the ‘DuoPack’ configuration, which integrates the IGBT chip with a soft-recovery, fast-recovery emitter-controlled diode within a single PG-TO-247-3 plastic package, with the ordering code IKW25N120T2FKSA1 and the silkscreen marking K25T1202.

The model designation clearly indicates the specifications: ‘IK’ denotes an IGBT with an anti-parallel diode (whereas a designation beginning with ‘IG’ indicates a single-chip IGBT without a diode); ‘W’ stands for the TO-247 package; 25 denotes a rated collector current of 25 A at a case temperature of 100 °C; 120 denotes a voltage rating of 1200 V; T2 refers to the TRENCHSTOP 2nd-generation platform, with chip technology derived from the trench-gate field-stop structure of Infineon’s fourth-generation IGBT (IGBT4). Its officially recommended switching frequency range is 2 kHz to 20 kHz; it is positioned as a ‘low-frequency hard-switching’ device that prioritises conduction losses whilst also taking switching losses into account, complementing the H3 series, which is designed for high-frequency operation.

II. Technical Platform and Structural Features of the IKW25N120T2

At the heart of this device lies a composite structure comprising a trench gate and a field stop. The trench gate transforms the channel from planar to vertical, enhancing cell density and transconductance; the field stop layer forms a buffer at the tail end of the drift region, enabling the chip to be manufactured thinner whilst maintaining a 1,200 V breakdown voltage, thereby simultaneously reducing the saturation voltage drop and turn-off tail current. Compared with earlier planar-gate IGBTs, this generation offers improvements in both static and dynamic characteristics, rather than simply trading on-state losses for switching losses.

The anti-parallel diode employs an emitter-controlled, high-efficiency (HE) design, characterised by a very soft recovery waveform and controllable recovery charge. This suppresses the peak reverse recovery current of the diode at the moment the IGBT turns on, thereby reducing turn-on losses and EMI. This is also the practical value of the ‘DuoPack’ package: the IGBT and its diode are designed and matched by the same manufacturer to fit the same chip area; users do not need to select a discrete fast-recovery diode themselves, saving space and costs whilst avoiding mismatching errors.

III. Key static parameters of the IKW25N120T2

Collector–emitter voltage (VCE) is 1200 V (measured at VGE = 0 V and IC = 500 µA); maximum gate–emitter voltage is ±20 V; operating junction temperature range is −40 °C to +175 °C; and storage temperature range is −55 °C to +150 °C.

Current capacity is divided into two levels: a DC collector current of 50 A at a case temperature (TC) of 25 °C, which drops to 25 A at TC = 110 °C; this explains the origin of the ‘25 A’ rating; The pulsed collector current ICPuls is 100 A (limited by Tjmax), whilst the safe operating area (SOA) for turn-off is also 100 A (VCE ≤ 1,200 V, Tj ≤ 175 °C). Diode side: forward current is 40 A at TC = 25 °C and 25 A at TC = 110 °C; pulsed current is 100 A.

The saturation voltage drop VCEsat, under conditions of VGE = 15 V and IC = 25 A, is typically 1.7 V at 25 °C (maximum 2.2 V), typically 2.1 V at 150 °C, and typically 2.2 V at 175 °C. These figures are on the lower side for the 1200 V/25 A class, directly reflecting the T2 platform’s ‘low VCEsat’ selling point. More importantly, VCEsat exhibits a positive temperature coefficient; the voltage drop increases rather than decreases at high temperatures. When multiple devices are connected in parallel, the current is naturally balanced, preventing thermal runaway caused by individual devices ‘snatching’ current; consequently, the manufacturer explicitly lists ‘easy parallelling’ as a feature.

Other static parameters: the gate threshold voltage VGEth is 5.2 V / 5.8 V / 6.4 V (minimum / typical / maximum), and the transconductance gfs is typically 13.5 S (VCE = 20 V, IC = 25 A). This wide distribution of threshold voltages means that the device is not directly compatible with logic-level drivers (such as 3.3 V or 5 V); a dedicated IGBT driver with a +15 V turn-on voltage must be used. The zero-gate-voltage leakage current ICES is approximately 0.4 mA at 25 °C and 1,200 V, approximately 4 mA at 150 °C, and can reach 20 mA at 175 °C; high-temperature blocking losses must be taken into account during high-voltage standby or in high-temperature environments and cannot be estimated using values for normal temperatures.

The forward voltage drop (VF) of the diode is typically 1.65 V at 25 °C and 1.7 V at 150 °C when IF = 25 A, with a maximum of 2.2 V.

IV. Dynamic Parameters and Switching Losses of the IKW25N120T2

Input capacitance Ciss is 1600 pF, output capacitance Coss is 155 pF, and reverse transfer capacitance Crss is 90 pF (VCE = 25 V, VGE = 0 V, 1 MHz); gate charge QGate is 120 nC (VCC = 960 V, IC = 25 A, VGE = 15 V). This set of data determines the drive power: estimated using the formula Qg × ΔVGE × fsw, the gate drive power at 10 kHz is approximately 0.12 µC × 23 V × 10 k, ≈ 28 mW. The load on the driver itself is very light; the main challenge lies in false triggering caused by dv/dt from the Miller capacitance, rather than insufficient drive power.

Under test conditions with an inductive load, VCC = 600 V, IC = 25 A, VGE = 0/15 V, and RG = 16.4 Ω, the switching characteristics at 25 °C are as follows: turn-on delay td (on) 27 ns, rise time tr 20 ns, turn-off delay td (off) 265 ns, fall time tf 95 ns, turn-on energy Eon 1.55 mJ, turn-off energy Eoff 1.35 mJ, and total switching energy Ets 2.9 mJ; at 175 °C, td (on) is 25 ns, tr is 24 ns, td (off) is 340 ns, tf is 164 ns, Eon 2.25 mJ, Eoff 2.05 mJ, Ets 4.3 mJ.

The most notable aspect of this set of data is the temperature effect: whilst the turn-on parameters remain virtually unchanged, the turn-off parameters deteriorate significantly, with tf increasing from 95 ns to 164 ns and Eoff rising by approximately 52 per cent. This is due to increased tail current at high temperatures, which is a common characteristic of all IGBTs. Consequently, thermal design calculations must not be based on the Eoff value at 25°C; a safety margin must be applied using values for 125°C or 175°C, otherwise the actual temperature rise will exceed expectations. Furthermore, the data sheet specifies that Eon already includes the diode reverse recovery loss; when using Ets for system-level estimation, do not add the Qrr loss separately to avoid double-counting.

Based on an Ets of 4.3 mJ at 175°C, the switching losses are approximately 43 W at 10 kHz and approximately 86 W at 20 kHz; this explains why the manufacturer has set the upper limit at 20 kHz—at higher frequencies, switching losses would rapidly erode the efficiency gains, which would then fall within the realm of H3 or IGBT7 devices.

V. Details of the IKW25N120T2 anti-parallel diodes

The diode reverse recovery time (trr) under conditions of VR = 600 V, IF = 25 A, and diF/dt ≈ 1050 A/µs is 195 ns at 25°C and 290 ns at 175°C; The reverse recovery charge (Qrr) is 2.05 µC at 25 °C and 3.65 µC at 175 °C; the peak reverse recovery current (Irrm) is 20 A at 25 °C and 24 A at 175 °C; the slope of the recovery current decay (dirr/dt) is 475 A/µs at 25 °C and 330 A/µs at 175 °C.

The ‘soft’ nature of this set of data is reflected in the relatively gentle dirr/dt, which slows further at high temperatures; the recovery process lacks a steep current drop-off, and therefore does not induce large voltage spikes across the bus parasitic inductance, resulting in good EMI performance. The trade-off is a relatively high Qrr (3.65 µC at 175°C); in a 20 kHz hard-switching bridge arm, diode recovery losses will account for a significant proportion of the total losses. The engineering trade-off is as follows: if the application prioritises low noise, low voltage spikes and overall system reliability, this soft-recovery combination is well-suited; if the aim is to achieve the highest possible high-frequency efficiency, then diodes with faster recovery times, such as those compatible with the H3 or IGBT7, should be used instead.

VI. IKW25N120T2 Short-Circuit Capability and Safe Operating Area

The short-circuit withstand time (tSC) is 10 µs, under test conditions of VGE = 15 V, VCC ≤ 600 V, and an initial junction temperature of 175 °C; it is specified that the number of short-circuit cycles must be less than 1,000, with an interval of more than 1 s between each short-circuit event. Regarding short-circuit current, under conditions of VGE = 15 V, VCC = 600 V and tSC ≤ 10 µs, the typical short-circuit current is 150 A at an initial junction temperature of 25 °C and 115 A at an initial junction temperature of 175 °C, which is approximately 4.6 to 6 times the rated current.

The 10 µs window imposes clear requirements on protection design: the blanking time for desaturation detection must be less than 10 µs, and the soft-shutdown slope must be sufficiently gentle to prevent the di/dt at the moment of shutdown from inducing overvoltage across stray inductance and causing breakdown. A short circuit lasting longer than 10 µs will inevitably lead to failure; therefore, this is not ‘optional protection’ but a mandatory requirement. It should also be noted that at an initial junction temperature of 175°C, the short-circuit current decreases and the window becomes tighter; therefore, a margin must be allowed for the protection threshold under high-temperature, heavy-load operating conditions.

VII. Thermal Design and Power Dissipation Estimation for the IKW25N120T2

The thermal resistance Rthjc (IGBT) is 0.43 K/W, the diode Rthjc is 0.81 K/W, and the junction-to-ambient thermal resistance Rthja is 40 K/W (without a heat sink, natural convection; for reference only). At TC = 25 °C, the total power dissipation Ptot is 349 W, derating linearly with case temperature.

A rough calculation based on typical operating conditions of 25 A, 150 °C and 10 kHz: the conduction loss is approximately 25 A × 2.1 V ≈ 52.5 W, and the switching loss is approximately 2.9 to 4.3 mJ × 10 kHz ≈ 29 to 43 W; the sum of these is approximately 80 to 95 W. Assuming an Rthjc of 0.43 K/W, the temperature difference between the junction and the case alone is 35 to 41 K; if the case temperature is controlled at 80 °C, the junction temperature is already close to 120 to 125 °C, leaving some headroom before the 175 °C upper limit, but this margin will narrow rapidly at 20 kHz. This indicates that the device is suitable for applications involving ‘medium frequencies, high currents, and a well-designed heat sink’, rather than forcing a small heat sink to cope with high frequencies.

The thermal resistance of the diode is nearly double that of the IGBT (0.81 K/W); in bridge circuits where the free-wheeling duty cycle is high or the power factor is low (i.e. high reactive power component), the diode junction temperature may reach its limit first. When selecting a heat sink and calculating junction temperature, the diode must be calculated separately; one must not rely solely on the thermal resistance curve for the IGBT.

VIII. Key Design Considerations for the IKW25N120T2 Driver and Parallel Configuration

For the gate driver, a turn-on voltage of +15 V and a turn-off voltage of approximately −8 V are recommended. A negative turn-off bias significantly improves resistance to dv/dt-induced false triggering, which is particularly important for 1200 V devices. The switching parameters in the data sheet are given for RG = 16.4 Ω; when selecting a resistor in practice, adjustments can be made around this value: increasing RG reduces di/dt and spikes, and suppresses EMI, but increases switching losses; decreasing RG has the opposite effect. As Eon includes diode recovery, the resistance on the turn-on side should not be set too low, otherwise the peak recovery current and oscillations will increase.

The internal gate resistance RGint of the TO-247 package is 0, meaning that the entire gate resistance is provided externally, offering considerable design flexibility. However, this also implies that there is no internal damping; even slightly longer gate circuit traces can easily lead to oscillation. Therefore, the layout should position the drive circuit as close to the device as possible, utilise a single-point ground, and prevent coupling between the power circuit and the gate circuit. The internal emitter inductance (LE) is approximately 13 nH (measured 5 mm from the case). Under common-emitter inductance effects, this value will limit the turn-off speed and increase voltage spikes; this is an area where Kelvin connections or compact busbars should be used during layout to suppress such effects.

Regarding parallel operation, the positive temperature coefficient of VCEsat naturally facilitates static current sharing, which is officially termed ‘easy parallelling’. However, two points require attention when parallelling: firstly, the 5.2 to 6.4 V spread in VGEth will cause slight variations in turn-on timing; dynamic current sharing must be balanced using independent gate resistors for each device; secondly, after parallelling, the total Qg and Ciss increase exponentially, so the peak current of the driver must be amplified accordingly. It is not recommended to share a single gate resistor amongst multiple devices.

IX. Typical Application Scenarios for the IKW25N120T2

Given its specifications of 1200 V, 25 A and 2 to 20 kHz, this device is most typically used in: the inverter and PFC stages of uninterruptible power supplies (UPS); frequency converters and general-purpose frequency converters; medium-to-low-power half-bridge or single-ended topologies in arc welders and induction heating; low-power grid-connected or off-grid stages in photovoltaic and energy storage systems; hard-switching half-bridges in chargers and industrial power supplies; and the power range around 1 kW in three-phase motor drives.

In applications where a 380 V three-phase rectifier produces a bus voltage of approximately 540 V, or where a single-phase 220 V supply is stepped up to a 400 V bus, the margin provided by the 1,200 V withstand voltage, combined with RCD clamping or soft switching, is sufficient to handle turn-off spikes and mains fluctuations—something that 600 V-class devices cannot achieve. If the bus operates at 800V or above for extended periods, the surge margin must be reassessed, or a four-pin package with a Kelvin emitter should be used to improve turn-off overvoltage protection.

Summary: The IKW25N120T2 is a 1200V/25A hard-switching IGBT with a clearly defined application and excellent parameter consistency. Its value lies not in extreme performance, but in its ability to ensure stability, ease of design and cost control across the broadest industrial power range—from 2 to 20 kHz—through its low saturation voltage drop, very ‘soft’ matching diodes, positive temperature coefficient (PTC) parallelability and 10 µs short-circuit withstand capability. Only by understanding its temperature characteristics, thermal resistance distribution and lifecycle status can this device be utilised to its full potential.