Modern ThinkPads come with a vast range of power supplies, gone are the days with the simple division in 65 W – iGPU and 90 W – dGPU. Since the CPUs in ThinkPads seem to become diversivied with every generation (one or two generations ago, the normal 35 W Dual-Core M-CPUs were the absolute standard, and now, Qud-Core CPUs oand ULV CPUs become more and more important and the old standard mormore irrelevant), Lenovo also introduced more power supply sizes, since “one size fits all” simply does not apply to power supplies.
Just two years ago, with the dawn of the Tx30 generation and at the dusk of the Tx20 generation, we had 3 different power supply sizes for ThinkPads:
- 65 W – for Dual-Core models with integrated graphics
- 90 W – for Dual-Core models with dedicated graphics
- 135/170 W – for 15.6″ Quad-Core models with dedicated grapics, the 170 W for W-Series only (these power supplies are also called “the brick”)
As mentioned before, since the introduction of the ThinkPad Helix and the Tx40 models, the situation is a bit more complex:
- 45 W – for Ultra Low Voltage (ULV, 15 W TDP) models like Helix, also used with T440(s), X240, integrated graphics only
- 65 W – for normal Dual-Core CPUs with iGPU and ULV CPUs with dGPU, and sometimes also without
- 90 W – for normal Dual-Core CPUs with dGPU
- 135 W – for Quad-Core without dGPU and also for T440p/T540p with Quad-Core and dGPU
- 170 W – for W540 with Quad-Core (dGPU is standard for the W540)
The most important thing to have in mind when purchasing a new spare power supply for your ThinkPad (or any laptop for that matter): It needs to supply enough power to charge your device and power it if you put load on it. Its very important that your power-supply isn´t underpowered – if it is, it may not charge your ThinkPad or your get throtteling if it can´t supply enough power. Alos, a bigger power supply might charger your ThinkPad faster in some cases.
As an extra note for T440p / T540p users with 135 W power supplys, look up this support notice from Lenovo: http://support.lenovo.com/us/en/products/laptops-and-netbooks/thinkpad-t-series-laptops/thinkpad-t440s/documents/HT082284?tabName=Solutions You may want to get a new one from Lenovo if you have one of the mentioned power supplies.