The MMUN2211LT1 already has a base resistor of 7~13kΩ with an hFE of 35 ~60 but it you apply 2.5V to base resistor it will saturate to 0.2Vmax with 5mA collector current.
So apply more base voltage to this device.
D.A.S.
- 148k
- 3
- 56
- 190