Design Note 97: Flash Memory VPP Generator Reference Design

The VPP generator circuits shown here cover a range of 30mA to 240mA with 3.3V or 5V inputs as noted. Table 1 summarizes these circuits for quick reference.

Table 1. Summary of Flash Memory VPP Generator Solutions
Number of Flash Chips Regulator
Advantages
VIN = 3.3V VIN = 5V VIN = 12.6V to 17V
1 LTC1262 No Inductors
2 LTC1263 No Inductors
 2 2 LT1106 PCMCIA Type I In-Card Use. Includes VPP Bank Switching for 4 Memory Chips
 2 4 LT1109A Low Cost
 2 4 LT1301 High Efficiency
4 LT1121 Linear Post Regulator
 4  8 LT1172 High Current

Figure 1. 30mA from 5V Input

Charge pump design uses no inductors. This is a minimum component count, minimum size solution.

Figure 2. 60mA from 5V Input

Charge pump design uses no inductors. This is a minimum component count, minimum size solution.

Figure 3. 60mA from 3.3V/5V Input

Designed for PCMCIA Type I or Type II in-card use. The LT1106 includes VPP bank switching for up to four memory chips.

Figure 4. 60mA/120mA from 3.3V/5V Input

All surface mount, minimum component count solution.

Figure 5. 60mA/120mA from 3.3V/5V Input

Efficiency is 84% to 88% at full load.

Figure 6. 120mA from 12.7V to 17V Input

This circuit serves as a post regulator for flyback converters or overwindings. Output automatically falls to zero in shutdown.

Figure 7. 120mA/240mA from 3.3V/5V Input

High output current converter programs up to eight memory chips simultaneously.

Figure 8. Output Disconnect

This shutdown circuit allows output to drop to zero when switching converter is disabled.

Об авторах

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Mitchell Lee