The simplified CMOS slew boost schematic, Figure 3-2, includes an additional current source that increases the capacitor charge current beyond the bias current level when V_ID becomes large enough. The boost function has a dead band with zero output current while input V_ID is low. At some greater V_ID, the boost current (I_X) rises with the V_ID input. This extra current increases the slew rate considerably. The boost circuit can provide positive and negative current flow to boost both positive and negative slew rates.

The boost current (I_X) versus V_ID can be proportionate or it can be stepped at a certain V_ID level. TLV9001 employs both methods, which is shown in Figure 3-3. Negative SR boost (red) increases proportionately starting near -140 mV. Positive slew rate boost (shown in black in Figure 3-3) increases suddenly near +270 mV, then raises proportionately. Regardless of the boost type, there is a limit to the boost current output. For very large V_ID, slew rate becomes a fixed value. In the TLV9001 example, the slower SR is about 2 V/µs, which matches the data sheet value.