TPS563212 Step-Down Converter Evaluation Module User's Guide

1 Introduction

The TPS563212 is a single, advanced emulated current mode (AECM) control, synchronous buck converter, that is able to deliver 3-A continuous output current, providing selectable Eco-mode operation or FCCM operation and a selectable power-good indicator or external soft start by the configuring the MODE pin. Power sequencing is possible by correctly configuring the enable, power-good indicator, or external soft start. The device implements an AECM control, which can get fast transient response with fixed frequency. The fast transient response results in low voltage drop and fixed frequency brings a better jitter permanence and predictable frequency for EMI design. The optimized internal compensation network minimizes the external component counts and simplifies the control loop design over a wide voltage output range. Rated input voltage and output current ranges for the evaluation module are given in Table 1-1.

The TPS563212EVM is a single, synchronous buck converter providing 3.3 V at 3 A from a 4.2-V to 18-V input. This user’s guide describes the TPS563212EVM performance.

Table 1-1 Input Voltage and Output Current Summary

EVM	INPUT VOLTAGE RANGE	OUTPUT CURRENT RANGE
TPS563212EVM	V_IN = 4.2 V to 18 V	0 A to 3 A

2 Performance Specification Summary

A summary of the TPS563212EVM performance specifications is provided in Table 2-1. Test specifications are given for an input voltage of V_IN = 12 V and an output voltage of 3.3 V, unless otherwise noted. The ambient temperature is 25°C for all measurement, unless otherwise noted.

Table 2-1 Performance Specifications Summary

SPECIFICATIONS	TEST CONDITIONS	MIN	TYP	MAX	UNIT
Input voltage range		4.2	12	18	V
Output voltage set point			3.3		V
Operating frequency	V_IN = 12 V, I_O = 3 A		1200		kHz
Output current range		0		3	A
Output ripple voltage	V_IN = 12 V, I_O = 3 A		20		mV_PP

3 Modifications

This evaluation module is designed to provide access to the features of the TPS563212. Some modifications can be made to this module.

3.1 MODE Pin Configuration

The TPS563212 has a MODE pin that can offer two different states of operation under light load conditions, and offer two options for the function of Pin 1.

Table 3-1 MODE Pin Settings

MODE RESISTOR RANGE	RECOMMENDED MODE RESISTOR VALUE	OPERATION MODE in LIGHT LOAD	FUNCTION of PG/SS PIN
[0, 12] kΩ	0	Eco-mode	Power Good⁽¹⁾
[30, 50] kΩ	47 kΩ	Eco-mode	Soft Start
[83, 120] kΩ	100 kΩ	FCCM	Soft Start
[180, ∞] kΩ	Float	FCCM	Power Good

(1) Connect pin 1 to GND to get a better thermal performance if the PG was not used when PG function was selected.

3.2 Output Voltage Setpoint

The output voltage is set with a resistor divider from the output node to the FB pin. TI recommends using 1% tolerance or better divider resistors. Referring to the application schematic of Figure 6-1, start with 10 kΩ or 20 kΩ for R9 and use Equation 1 to calculate R8. To improve efficiency at light loads, consider using larger value resistors. If the values are too high, the regulator is more susceptible to noise and voltage errors from the FB input current are noticeable.

Equation 1.

Table 3-2 lists the R8 and R9 values for some common output voltages. Note that the values given in Table 3-2 are standard values and not the exact value calculated using above equation.

Table 3-2 Recommended Component Values

OUTPUT VOLTAGE⁽¹⁾ (V)	R8⁽²⁾ (kΩ)	R9 (kΩ)	L1⁽³⁾ (µH)	C_OUT⁽⁴⁾ (µF)	RANGE of L1·C_{OUT_E}⁽⁵⁾ (μH × μF)	C7⁽⁶⁾ (pF)
0.76	5.36	20.0	0.56	2 × 22	17 to 130	—
1.05	15.0	20.0	0.68	2 × 22	17 to 130	10 to 100
1.8	40.0	20.0	1.0	1 × 22	15 to 160	10 to 100
2.5	31.6	10.0	1.5	1 × 22	15 to 160	10 to 100
3.3	45.3	10.0	2.2	1 × 22	15 to 160	10 to 100
5	73.2	10.0	3.3	1 × 22	15 to 160	10 to 100

(1) Use the recommended L1 and C_OUT combination of the higher and closest output rail for the unlisted output rails.

(2) R8 = 10 kΩ and R9 = Float for V_OUT = 0.6 V

(3) Inductance values are calculated based on V_IN=18 V, but they can also be used for other input voltages. Users can calculate their preferred inductance value per the TPS563212 4.2-V-18-V Input, 3-A Synchronous Buck Converter in a SOT-5X3 Package Data Sheet.

(4) The C_OUT is the sum of nominal output capacitance. 22-μF, 0805, 10-V or higher specification capacitors are recommended .

(5) The C_{OUT_E} is the effective value after derating. The value of L1·C_{OUT_E} should be within in the range.

(6) R6 and C7 can be used to improve the load transient response and improve the loop-phase margin.