NCP1729 Vin −Vout 1 6 1 6 OSC OSC + + + 2 5 2 5 + + 3 4 3 4 Capacitors = 3.3 F Figure 20. Cascaded Devices for Increased Negative Output Voltage Two or more devices can be cascaded for increased output voltage. Under light load conditions, the output voltage is approximately equal to −Vin times the number of stages. The converter output resistance increases dramatically with each additional stage. This is due to a reduction of input voltage to each successive stage as the converter output is loaded. Note that the ground connection for each successive stage must connect to the negative output of the previous stage. The performance characteristics for a converter consisting of two cascaded devices are shown below. −1.0 −2.0 −3.0 B AGE (V) −4.0 T −5.0 −6.0 A −7.0 CurveVin (V)Rout () , OUTPUT VOL −8.0 A 5.0 145 outV −9.0 TA = 25°C B 3.0 180 −10.00 10 20 30 40 Iout, OUTPUT CURRENT (mA) Figure 21. Cascade Load Regulation, OutputVoltage vs. Output Currenthttp://onsemi.com8