General Description
The RTQ2158 is a high-performance, synchronous step-down converter that can deliver up to 8A output current with an input supply voltage range of 2.85V to 6.5V. This document explains the function and use of the RTQ2158 evaluation board (EVB), and provides information to enable operation, modification of the evaluation board, bill of materials and schematic to meet individual requirements.
Performance Sepcification Summary
Summary of the RTQ2158 Evaluation Board performance specificiaiton is provided in Table 1. The ambient temperature is 25°C.
Table 1. RTQ2158 Evaluation Board Performance Specification Summary
|
Specification
|
Test Conditions
|
Min
|
Typ
|
Max
|
Unit
|
|
Input Voltage Range
|
|
2.85
|
--
|
6.5
|
V
|
|
Output Current
|
|
--
|
8
|
--
|
A
|
|
Default Output Voltage
|
|
--
|
1.2
|
--
|
V
|
|
Operation Frequency
Output Ripple Voltage
|
|
--
|
460
|
--
|
kHz
|
|
IOUT = 8A
|
--
|
10
|
--
|
mVp-p
|
|
Line Regulation
|
IOUT = 8A, VIN = 3V to 6.5V
|
--
|
±1
|
--
|
%
|
|
Load Regulation
|
VIN = 5V, IOUT = 0A to 8A
|
--
|
±1
|
--
|
%
|
|
Load Transient Response
|
IOUT = 0A to 8A
|
--
|
±5
|
--
|
%
|
|
Maximum Efficiency
|
VIN = 5V, VOUT = 1.2V, IOUT = 8A
|
--
|
77
|
--
|
%
|
Power-up Procedure
Suggestion Required Equipment
- RTQ2158GQWT Evaluation Board
- DC power supply capable of 10A
- Electronic load capable of 12A
- Function Generator
- Oscilloscope
Quick Start Procedure
The Evaluation Board is fully assembled and tested. Follow the steps below to verify board operation. Caution: Do not turn on supplies until all connections are made. Note: When measuring the output voltage ripple, care must be taken to avoid a long ground lead on the oscilloscope probe. Measure the output voltage ripple by touching the probe tip and ground ring directly across the last output capacitor.
Proper measurement equipment setup and follow the procedure below.
1. Turn off the power and connect the input power supply to the VIN and GND pins.
2. Turn off the power and connect the electronic load between the VOUT and the nearest GND pins.
3. Turn on the power supply at the input, ensuring that the input voltage does not exceed 5V on the Evaluation Board.
4. Use a voltmeter to check for the proper output voltage.
5. Once the proper output voltage is established, adjust the load within the operating ranges and observe the output voltage regulation, ripple voltage, efficiency, and other performance metrics.
Detailed Description of Hardware
Headers Description and Placement
Carefully inspect all the components used in the EVB according to the following Bill of Materials table, and then make sure all the components are undamaged and correctly installed. If there is any missing or damaged component, which may occur during transportation, please contact our distributors or e-mail us at evb_service@richtek.com.
Enable
To automatically start, pull the EN pin to VIN through JP2. Similarly, the converter can be shut down by shorting the EN pin to GND through JP2.
Test Points
The EVB is provided with the test points and pin names listed in the table below.
|
Test point/
Pin Name
|
Function
|
|
EN
|
Enable control input.
|
|
BOOT
|
Supply for high-side gate driver.
|
|
SW
|
Switch node.
|
|
PGND
|
System GND.
|
|
VIN
|
Support 2.85V to 6.5V input voltage.
|
|
AVCC
|
Internal regulator output.
|
|
AGND
|
Signal ground.
|
|
PG
|
Open-drain, power-good indication output.
|
|
SS
|
Soft-start time control pin.
|
|
FB
|
Feedback input.
|
Bill of Materials
|
Reference
|
Qty
|
Part Number
|
Description
|
Package
|
Manufacturer
|
|
U1
|
1
|
RTQ2158GQWTF-QA
|
Step-Down DC-DC Converter
|
WET-WQFN-21L 4x4 (FC)
|
RICHTEK
|
|
C1, C2, C9, C10, C11, C12
|
6
|
GRM187R61A226ME15
|
22µF/10V/X5R
|
0603
|
MURATA
|
|
C3, C5, C8
|
3
|
0603B104K500CT
|
100nF/50V/X7R
|
0603
|
WALSIN
|
|
C4
|
1
|
GRM188R61E475KE11D
|
4.7µF/10V/X5R
|
0603
|
MURATA
|
|
L1
|
1
|
WURTH 744316022
|
0.47µH
|
5040
|
WE
|
|
R1, R2
|
2
|
WR06X1003FTL
|
100k
|
0603
|
WALSIN
|
|
R3
|
1
|
WR06X20R0FTL
|
20
|
0603
|
WALSIN
|
|
R5, R6
|
2
|
RAT030000FTP
|
0
|
0603
|
RALEC
|
|
R7
|
1
|
WR06X1332FTL
|
13.3k
|
0603
|
WALSIN
|
|
R8
|
1
|
WR06X2002FTL
|
20k
|
0603
|
WALSIN
|
|
R9, R10, R11, R12
|
4
|
WR06X1002FTL
|
10k
|
0603
|
WALSIN
|
Typical Applications
EVB Schematic Diagram
RTQ2158GQWTF demo board: VIN = 5V, VOUT 1.2V / 8A
1. The capacitance values of the input and output capacitors will influence the input and output voltage ripple.
2. MLCC capacitors have degrading capacitance at DC bias voltage, and especially smaller size MLCC capacitors will have much lower capacitance.
Measurement Results
|
Output Ripple Measurement
at VIN = 5V 8A load, VOUT = 1V
|
Output Ripple Measurement
at VIN = 5V 8A load, VOUT = 2.5V
|
|
|
|
|
Dynamic Load 0A to 8A Load Step, VOUT = 1V
|
Dynamic Load 0A to 8A Load Step, VOUT = 2.5V
|
|
|
|
|
Start-Up Measurement from Enable:
EN Pin Low to High
|
Power-Off Measurement from Enable:
EN Pin High to Low
|
|
|
|
Evaluation Board Layout
Figure 1. Top View (1st layer)
Figure 2. PCB Layout—Inner Side (2nd Layer)
Figure 3. PCB Layout—Inner Side (3rd Layer)
Figure 4. Bottom View (4th Layer)