SP202E_04 Datasheet, PDF (7/15 Pages) Sipex Corporation – High-Performance RS-232 Line Drivers/Receivers

+10V
a) C₂₊
GND
GND
b) C_2–
–10V
Figure 6. Charge Pump Waveforms
be symmetrical. Older charge pump approaches
that generate V^– from V⁺ will show a decrease in
the magnitude of V^– compared to V⁺ due to the
inherent inefficiencies in the design.
The clock rate for the charge pump typically
operates at 15kHz. The external capacitors can
be as low as 0.1µF with a 16V breakdown
voltage rating.
V_CC = +5V
Shutdown (SD) and Enable (EN) for the
SP310E and SP312E
Both the SP310E and SP312E have a shutdown/
standby mode to conserve power in battery-pow-
ered systems. To activate the shutdown mode,
which stops the operation of the charge pump, a
logic “0” is applied to the appropriate control line.
For the SP310E, this control line is ON/OFF (pin
18). Activating the shutdown mode also puts the
+
C_{1 –}
–5V
+5V
+
C_{2 –}
–5V
C₄
+ – _{VDD Storage Capacitor}
– + _{VSS Storage Capacitor}
C₃
Figure 7. Charge Pump — Phase 3
V_CC = +5V
+
C_{1 –}
+10V
+
C_{2 –}
C₄
+ – _{VDD Storage Capacitor}
– + _{VSS Storage Capacitor}
C₃
Figure 8. Charge Pump — Phase 4
Date: 7/19/04
SP202E Series High Performance RS232 Transceivers
7
© Copyright 2004 Sipex Corporation