General Description
The Evaluation Board user guide describes the operational use of the RTQ2531W evaluation board as a reference design for demonstration and evaluation of the RTQ2531W, a low-noise, high accuracy, low-dropout (LDO) linear regulator.
Included in this user guide are setup and operating instructions, thermal and layout guidelines, a printed circuit board (PCB) layout, a schematic diagram, and a bill of materials (BOM). For more detail information, please refer to the RTQ2531W datasheet
Performance Specification Summary
Summary of the RTQ2531W Evaluation Board performance specificiaiton is provided in Table 1. The ambient temperature is 25°C.
Table 1. RTQ2531W Evaluation Board Performance Specification Summary
|
Specification
|
Test Conditions
|
Min
|
Typ
|
Max
|
Unit
|
|
Input Voltage Range
|
|
1.7
|
3.8
|
5.5
|
V
|
|
Output Current
|
|
0
|
--
|
0.5
|
A
|
|
Output Voltage Range
|
|
0.6
|
3.3
|
5.3
|
V
|
|
Line Regulation
|
1.7V ≤ VIN ≤ 5.5V for VOUT ≤ 1.4V,
VOUT + 0.3V ≤ VIN ≤ 5.5V for VOUT ≥ 1.4V,
IOUT = 200mA
|
--
|
0.04
|
--
|
%/V
|
|
Load Regulation
|
0.1mA ≤ IOUT ≤ 500mA
|
--
|
0.02
|
--
|
%/A
|
|
Load Transient Response
|
IOUT = 50mA to 500mA to 50mA,
tRISE = tFALL = 1µs
|
--
|
50
|
--
|
mV/P-P
|
Power-up Procedure
Suggestion Required Equipments
- RTQ2531W Evaluation Board
- DC power supply capable of at least 5.5V and 500mA
- Electronic load capable of 500mA
- Function Generator
- Oscilloscope
Quick Start Procedures
The Evaluation Board is fully assembled and tested. Follow the steps below to verify board operation. Do not turn on supplies until all connections are made. 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 groundring directly across the last output capacitor.
Proper measurement equipment setup and follow the procedure below.
1) With power off, connect the input power supply to VIN and GND pins.
2) With power off, connect the electronic load between the VOUT and nearest GND pins.
3) Turn on the power supply at the input. Make sure that the input voltage does not exceeds 6V on the Evaluation Board.
4) Check for the proper output voltage using a voltmeter.
5) Once the proper output voltage is established, adjust the load within the operating ranges and observe the output voltage regulation, quiescent current, dropout voltage, PSRR, noise and other performance.
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.
Test Points
The EVB is provided with the test points and pin names listed in the table below.
|
Test Point/
Pin Name
|
Function
|
|
VIN
|
Supply input pin.
|
|
GND
|
System ground pin.
|
|
EN
|
Enable sense pin.
|
|
POK
|
Power-OK sense pin.
|
|
VOUT
|
Output of the regulator.
|
|
EN1
|
User can decide EN pin connected to high or low.
|
|
POK1
|
User can decide POK pin connected to high or low.
|
|
JP2
|
Short to by-pass resistor R3.
|
|
JP7
|
Pins to change resistor divider.
|
Bill of Materials
|
VIN = 1.7V to 5.5V, VOUT = 0.6V to 5.3V, IOUT = 500mA
|
|
Reference
|
Count
|
Part Number
|
Value
|
Description
|
Package
|
Manufacturer
|
|
U1
|
1
|
RTQ2531WGQW
|
RTQ2531W
|
LDO
|
WDFN-8SL 2x2
|
RICHTEK
|
|
C6
|
1
|
0603B103K500CT
|
10nF
|
Capacitor, ceramic,
50V, X7R
|
0603
|
WALSIN
|
|
C11, C12
|
2
|
GRM21BR71A106KE51L
|
10μF
|
Capacitor, ceramic,
10V, X7R
|
0805
|
MURATA
|
|
R1
|
1
|
WR06X2673FTL
|
267k
|
Resistor, chip
|
0603
|
WALSIN
|
|
R2
|
1
|
WR06X5902FTL
|
59k
|
Resistor, chip
|
0603
|
WALSIN
|
|
REN1, REN2, REN3
|
3
|
WR06X1003FTL
|
100k
|
Resistor, chip
|
0603
|
WALSIN
|
Typical Applications
EVB Schematic Diagram
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.
Measure Result
|
Power Up Response
|
Dropout Voltage vs. Output Current
|
|
|
|
|
Quiescent Current
|
Line Transient Response
|
|
|
|
|
Load Transient Response
|
PSRR vs. Frequency
|
|
|
|
|
Output Noise vs. Frequency
|
OCP
|
|
|
|
|
Bode Plot
|
|
|
|
|
Note: When measuring the input or 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 directly across the output capacitor.
Evaluation Board Layout
Figure 1 and Figure 2 are RTQ2531W Evaluation Board layout. This board is constructed on two-layer PCB, outer layers with 1 oz. Cu and inner layers with 1 oz. Cu.
Figure 1. Top View (1st layer)
Figure 2. Bottom View (2nd Layer)