AN2433 Freescale Semiconductor / Motorola, AN2433 Datasheet - Page 22

• Manufacturer Part Number: AN2433
• Description: 5V to 3V Design Considerations
• Manufacturer: Freescale Semiconductor / Motorola

AN2433/D
22
Input Power
Input Bypass
5uF to 100uF
+
Typically, in a linear voltage regulator design, the input bypass (bulk) capacitor
is placed close to the input terminal of the regulator. The input bypass capacitor
provides a low impedance source into the voltage regulator. Typical input
bypass capacitors are in the 5 F to 100 F range. Connected to the output
side of the voltage regulator will be another bulk capacitor (output bypass), in
the range from 1 F to 100 F. This capacitor helps stabilize the regulator
during current transients until its internal control loop can take over. It is also
standard practice to bypass the logic elements, connected to the 3.3 V voltage
regulator, with small bypass capacitors located close to their power leads.
These small bypass capacitors help provide a low impedance power source
during very fast transient current demands. Depending on the frequency of the
transients, the value of these capacitors will range from 100 pF to 1000 pF.
Figure 18
Figure 18. Typical Linear Regulator Schematic
1
Freescale Semiconductor, Inc.
ON Semiconductor
ON Semiconductor
ON Semiconductor
ON Semiconductor
ON Semiconductor
ON Semiconductor
Linear Technology
Linear Technology
Linear Technology
Linear Technology
Semiconductor
Semiconductor
Linear Voltage Regulator
VIN
Manufacturer
For More Information On This Product,
National
National
shows a schematic for a typical linear voltage regulator.
5V to 3V Design Considerations
Go to: www.freescale.com
VOUT
2
MC78PC33NTR
CS5207-3GDP3
LM2936DT-3.3
LT1083CK-3.3
CS5206-1GT3
LT1086CT-3.3
LT1085CT-3.3
+
LM3940IT-3.3
LT1121N8-3.3
Part Number
CS52015-3L
Output Bypass
1uF to 100uF
CS5201-3L
CS5203-3L
Small bypass Capacitors
100pF to 1000pf
Current
Output
150mA
150mA
50mA
1.0A
1.5A
1.5A
7.5A
3A
6A
7A
1A
3A
Dropout
Voltage
300mV
200mV
500mV
400mV
1.15V
1.2 V
1.4V
1.3V
1.4V
1.5V
1.5V
1.5V
3.3 Volt output
MOTOROLA
Tolerance
+-1.5%
+-1.5%
+-1.5%
+-2%
+-2%
+-2%
+-3%
+-3%
+-3%
+-2%
+-2%
+-2%