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.
| 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.
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