SP3508EB Exar Corporation, SP3508EB Datasheet - Page 28

• Manufacturer Part Number: SP3508EB
• Description: LIN Transceivers 20Mbps Multiprotocol Transceiver 8Ch 3.3V
• Manufacturer: Exar Corporation
• Series: -r

Specifications of SP3508EB

• Main Purpose: Interface, Transceiver RS-232, RS-449, EIA-530(A), X.21
• Embedded: No
• Utilized Ic / Part: SP3508
• Primary Attributes: Internal Line or Digital Loopback Testing
• Secondary Attributes: 8 Drivers and 8 Receivers
• Lead Free Status / Rohs Status: Details

Figure 46. Charge Pump - Phase 2.
Figure 47.Charge Pump - Phase 3.
-V
and transfers the generated 5.5V across C2 to C
is regulated to +5.5V. At the regulated voltage, the internal oscillator is disabled and simulta-
neously with this, the positive side of capacitor C is switched to V
is connected to ground, and the cycle begins again. The charge pump cycle will continue as
long as the operational conditions for the internal oscillator are present. Since both V+ and
V- are separately generated from V
Older charge pump approaches that generate V- from V+ will show a decrease in the mag-
nitude of V- compared to V+ due to the inherent inefficiencies in the design. The clock rate
for the charge pump typically operates at 250kHz. The external capacitors can be as low as
µF with a 6V breakdown voltage rating.
Phase 2
-V
capacitor and the positive terminal of C2 to ground, and transfers the negative generated
voltage to C
side of the capacitor C is switched to V
Phase 3
-V
transferred in C produces -V
side of the capacitor C2. Since C2+ is at V
Phase 4
DD
SS
DD
transfer -The fourth phase of the clock connects the negative terminal of C2 to ground,
charge storage -The third phase of the clock is identical to the first phase-the charge
transfer -Phase two of the clock connects the negative terminal of C2 to the V
VSS
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • (50)668-707 • www.exar.com
. This generated voltage is regulated to -5.5V. Simultaneously, the positive
C
C
1
–3 V
1
+
–
CC
+
–
V
V
CC
in the negative terminal of C which is applied to the negative
CC
= +3V
= +3V
CC
; in a no-load condition V+ and V- will be symmetrical.
CC
C
C
2
+3V
–3 V
CC
and the negative side is connected to ground.
2
+
–
–6 V
28
+
–
, the voltage potential across C2 is 2xV
VDD
, the V
+
C
–
C
VSS1
VDD
+
C
C
–
+
–
VSS1
DD
VDD
+
–
V
V
storage capacitor. This voltage
DD
SS1
V
V
DD
SS
S tora ge C apacitor
S tora ge C apacitor
S tora ge C apacitor
S tora ge C apacitor
CC
and the negative side
SP3508_00_072208
FEATURES
SS
storage
CC
.