View cs1009.rev4 datasheet:

CS1009 2.5 Volt Reference Description Features The CS1009 is a precision trimmed A third terminal allows the refer- 0.2% initial tolerance max. 2.500V ±5mV shunt regulator ence voltage to be adjusted ±5% to Guaranteed temperature diode. The low dynamic calibrate out system errors. In stability impedance and wide operating many applications, the CS1009GZ current range enhances its versatil- can be used as a pin-to-pin replace- Maximum 0.6? dynamic ity. The tight reference tolerance is ment of the LT1009CZ and the impedance achieved by on-chip trimming LM136Z-2.5 with the external trim Wide operating current which minimizes voltage tolerance network eliminated. range and temperature drift. Directly interchangeable with LT1009 and LM136 Absolute Maximum Ratings for