Microcontroller Pin Configuration and Functions

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Questions and Answers

What is the primary focus of the 'Specifications' section?

System examples and power supply recommendations

Electrical characteristics and thermal information (correct)

Device support and documentation

Pin configuration and layout guidelines

What is the purpose of the 'Revision History' section?

To provide information on device support and documentation

To explain the pin configuration and functions

To document changes and updates to the device (correct)

To provide an overview of the device's features

What is the main topic of the 'Detailed Description' section?

System examples and power supply recommendations

Electrical characteristics and thermal information

Overview and detailed explanation of the device's features (correct)

Pin configuration and functions

What is the primary focus of the 'Power Supply Recommendations' section?

Power supply design and recommendations Signup and view all the answers

What is the purpose of the 'Layout' section?

To provide guidance on layout and thermal design Signup and view all the answers

What is the main topic of the 'System Examples' section?

System examples and applications Signup and view all the answers

What is the purpose of the 'Pin Configuration and Functions' section?

To describe the pin configuration and functions Signup and view all the answers

What is the primary focus of the 'Device and Documentation Support' section?

Device support and documentation resources Signup and view all the answers

What is the primary source of transient current supply when there is a sudden increase in source current?

Charge from the VLDOIN input capacitor Signup and view all the answers

What is the recommended value of input capacitance when using a larger output capacitance at the VO pin?

One-half of the COUT value Signup and view all the answers

What is the minimum total capacitance required for stable operation at the VO output pin?

20 μF Signup and view all the answers

Why is it recommended to attach three 10-μF ceramic capacitors in parallel at the VO output pin?

To minimize the effect of ESR and ESL Signup and view all the answers

What is the recommended action when the equivalent series resistance (ESR) is greater than 2 mΩ?

Insert an RC filter between the output and the VOSNS input Signup and view all the answers

What is the approximate unity-gain bandwidth of the DDR3 design example in the TPS51200 device?

1 MHz Signup and view all the answers

What is the phase margin of the DDR3 design example in the TPS51200 device?

52° Signup and view all the answers

What is the result of subjecting the regulator to a ±1.5-A load step and release in a typical DDR3 configuration?

No difference in output voltage between dc and ac conditions Signup and view all the answers

What is the input voltage for the design example in Figure 24?

3.3 V Signup and view all the answers

What is the purpose of adding a ceramic capacitor close to the VIN pin?

To stabilize the bias supply Signup and view all the answers

What is the value of the resistors R1 and R2 in the design example?

10 kΩ Signup and view all the answers

What is the output voltage of the LDO linear regulator in the design example?

1.5 V Signup and view all the answers

What is the purpose of the capacitor C5 in the design example?

To provide a reference voltage Signup and view all the answers

What is the value of the capacitor C4 in the design example?

1000 pF Signup and view all the answers

What is the purpose of the resistors R3 in the design example?

To adjust the output voltage Signup and view all the answers

What is the value of the capacitor C6 in the design example?

4.7 μF Signup and view all the answers

What is the purpose of the LDO linear regulator in the design example?

To regulate the output voltage Signup and view all the answers

What is the value of the capacitor C1 in the design example?

10 μF Signup and view all the answers

Study Notes

Typical Application

The application is a 3.3-VIN, DDR3 configuration
The design uses a TPS51200 device with a 3.3-V input, and 1.5-V and 0.75-V outputs

Design Requirements

VIN = 3.3 V
VDDDQ = 1.5 V
VVLDOIN = VVDDQ = 1.5 V
VVTT = 0.75 V

Input Capacitor

Use a ceramic capacitor with a value between 1.0 μF and 4.7 μF
Place the capacitor close to the VIN pin to stabilize the bias supply

VLDO Input Capacitor

Use a 10-μF (or greater) ceramic capacitor to supply transient charge
Add more input capacitance as more output capacitance is used at the VO pin
Use one-half of the COUT value for input

Output Capacitor

Total capacitance of the VO output pin must be greater than 20 μF
Use three, 10-μF ceramic capacitors in parallel to minimize ESR and ESL
Insert an RC filter between the output and the VOSNS input if ESR is greater than 2 mΩ

Application Curves

Figure 25 shows the bode plot simulation for this DDR3 design example
Unity-gain bandwidth is approximately 1 MHz and the phase margin is 52°
Figure 26 shows the load regulation and Figure 27 shows the transient response for a typical DDR3 configuration