AAT2820 Datasheet, PDF (11/18 Pages) Advanced Analogic Technologies – Triple-Output Charge Pump Regulator

AAT2820
Triple-Output Charge Pump Regulator
Design Procedure and
Component Selection
Number of Stages for Dual Charge
Pump Regulators
The number of stages required can be determined by:
N_POS =
V_POS - 5
5 - 2V_FWD
for the positive output, and
N_NEG =
V_NEG
2V_FWD - 5
for the negative output.
Where,
V_NEG = Negative output voltage
V_POS = Positive output voltage
V_FWD = Forward voltage drop of the Schottky diode
(0.31V, based on BAT54SDW diode when
I_F = 4mA)
After solving for the number of stages (N_POS and
N_NEG), round up the solutions to the next highest
integers for the number of stages required.
Tables 1 and 2 show the number of stages required
for positive and negative charge pumps, respectively.
2820.2006.04.1.4
V_POS (V)
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
# of Stages (n)
1
1
1
2
2
2
2
3
3
3
3
3
4
4
4
4
5
5
5
Table 1: Number of Stages Required for
Positive Charge Pump.
V_NEG (V)
-7
-8
-9
-10
-11
-12
-13
-14
-15
-16
-17
-18
-19
-20
-21
-22
-23
-24
-25
# of Stages (n)
2
2
3
3
3
3
3
4
4
4
4
5
5
5
5
6
6
6
6
Table 2: Number of Stages Required for
Negative Charge Pump.
11