TINA/Spice/TPS61086: TPS61086

Part Number: TPS61086

Tool/software: TINA-TI or Spice Models

Hi,

I am trying to use the TPS61086 configured as a charge pump doubler. The boost converter is deisgned to boost voltage from 3.3V to 7V (Vout_boost net in the schematic attached). This voltage is then doubled and stored in a bank of three 820uF capacitors. (2Vout_boost net in the schematic attached). The working is as follows

When switch node SW = 0V i.e., the device is ON, the flying capacitor C3 is charged to Vout_boost – SD3 

When device is off, i.e., the switch is open then SW = Vout_boost + SD1.

 Now voltage on C10, C11, C12 becomes Vout_boost + SD1 + Vout_boost –SD3 = 2Vout_boost + SD1– SD3 and ignoring the diode voltage drops , this voltage of 2Vout_boost is transferred to the output capacitors C10, C11,C12

I am trying to simulate the output waveforms using TINA. The output waveform for Vout_boost net is correct - at approximately 7.2V but the waveform for the 2Vout_boost net  shows as 7V. 

What is wrong with the way I am trying to simulate and how can I get it work? I should be able to see Vout_boost as 7V and Vout_boost as aprroximately 12V considering diode voltage drops.