SP233A Datasheet, PDF (6/13 Pages) Exar Corporation – Enhanced RS-232 Line Drivers/Receivers

+
V
CC
Phases 1 and 3: Store/Double.
- _{Double charge from C1 onto C2.}
C2 is now charged to -2xVcc
C+
1
+
C
2
e^-
e^-
+
V+
C
3
V- ₊
C
4
+
V
CC
- _{Phase 2 – Vss transfer from C2 to C4.}
Meanwhile C1 is charged to Vcc
C+
1
e^-
+
C+
2
V+
C
3
e^-
e^-
+
C
4
Vss
Patented 5,306,954
C+
1
e^-
+
V
CC
-
Phase 4 VDD transfer from C2 to C3.
Meanwhile C1 is charged to Vcc
V
DD
e⁺
e⁺
+
C+
2
V+
C
3
V- +
C
4
Figure 1. Charge pump phases
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • [phone] • Fax [phone] • www.exar.com SP233A,310A,312A_100_051308