RT8296AHZSP Evaluation Board Table of Contents

RT8296AHZSP
Evaluation Board
Purpose
The RT8296A is a high-efficiency current mode synchronous step-down regulator that can deliver up to 3A output
current from a wide input voltage range of 4.5V to 23V. This document explains the function and use of the
RT8296A evaluation board (EVB) and provides information to enable operation and modification of the evaluation
board and circuit to suit individual requirements.
Table of Contents
Purpose .......................................................................................................................................... 1
Introduction .................................................................................................................................... 2
General Product Information ...................................................................................................... 2
Key Performance Summary Table ............................................................................................. 3
Bench Test Setup Conditions ......................................................................................................... 4
Headers Description and Placement .......................................................................................... 4
Test Points.................................................................................................................................. 4
Power-up & Measurement Procedure ........................................................................................ 5
Output Voltage Setting ............................................................................................................... 5
Schematic, Bill of Materials and Board Layout ............................................................................... 6
EVB Schematic Diagram ............................................................................................................ 6
Bill of Materials ........................................................................................................................... 7
EVB Layout................................................................................................................................. 8
Other Technical Information ......................................................................................................... 10
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RT8296AHZSP
Evaluation Board
Introduction
General Product Information
General Description
The RT8296A is a high efficiency, monolithic synchronous step-down DC/DC converter that can deliver up to 3A
output current from a 4.5V to 23V input supply. The RT8296A's current mode architecture and external
compensation allow the transient response to be optimized over a wide range of loads and output capacitors.
Cycle-by-cycle current limit provides protection against shorted outputs and soft-start eliminates input current surge
during start-up. The RT8296A also provides output under voltage protection and thermal shutdown protection. The
low current (<3μA) shutdown mode provides output disconnection, enabling easy power management in
battery-powered systems. The RT8296A is available in an SOP-8 (Exposed Pad) package.
Features
 ±1.5% High Accuracy Feedback Voltage
 4.5V to 23V Input Voltage Range
 3A Output Current
 Integrated N-MOSFET Switches
 Current Mode Control
 PWM Frequency Operation : 340kHz
 Output Adjustable from 0.8V to 20V
 Up to 95% Efficiency
 Programmable Soft-Start
 Stable with Low-ESR Ceramic Output Capacitors
 Cycle-by-Cycle Over Current Protection
 Input Under Voltage Lockout
 Output Under Voltage Protection
 Thermal Shutdown Protection
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RT8296AHZSP
Evaluation Board
Key Performance Summary Table
Key features
Evaluation board number: PCB004_V1
Default Input Voltage
12V
Max Output Current
3A
Default Output Voltage
3.3V
Default Marking & Package Type
RT8296AHZSP, PSOP-8 (Exposed Pad)
Operation Frequency
Steady 340kHz at PWM
Other Key Features
4.5V to 23V Input Voltage Range
Programmable Soft-Start
PSM/ PWM Auto Switched
Protection
Output Under-Voltage Protection (hiccup mode):
Cycle-by-cycle Current Limit
Thermal Shutdown
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RT8296AHZSP
Evaluation Board
Bench Test Setup Conditions
Headers Description and Placement
Please carefully inspect
the EVB IC and external components, comparing them to the
following Bill of Materials, to ensure that all components are installed and undamaged. If any
components are missing or damaged during transportation, please contact the distributor or
send e-mail to [email protected].
Test Points
The EVB is provided with the test points and pin names listed in the table below.
Test point/
Pin name
Signal
Comment (expected waveforms or voltage levels on test
points)
VIN
Input voltage
Input voltage range= 4.5V to 23V
VOUT
Output voltage
Default output voltage = 3.3V
Output voltage range= 0.8V to 20V
(see ‘’ Output Voltage Setting’’ section for changing output voltage
level)
SW
Switching node test point
SW waveform
EN
Enable test point
Enable signal. EN is automatically pulled high (by R4) to enable
operation. Connect EN low to disable operation.
BS
Boot strap supply test point
Floating supply voltage for the high-side N-MOSFET switch
SS
Soft-start control test point
Soft start waveform
GND
Ground
Ground
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RT8296AHZSP
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Power-up & Measurement Procedure
1. Apply a 12V nominal input power supply (4.5V < VIN < 23V) to the VIN and GND terminals.
2. The EN voltage is pulled to logic high by R4 (100kΩ to VIN) to enable operation. Drive EN high (>2.7V) to
enable operation or low (<0.4V) to disable operation.
3. Verify the output voltage (approximately 3.3V) between VOUT and GND.
4. Connect an external load up to 3A to the VOUT and GND terminals and verify the output voltage and current.
Output Voltage Setting
Set the output voltage with the resistive divider (R1, R2) between VOUT and GND with the midpoint connected to
FB. The output is set by the following formula:
VOUT = 0.8 x (1 +
R1
)
R2
The installed VOUT capacitors (C4, C5) are 22μF, 16V X5R ceramic types. Do not exceed their operating voltage
range and consider their voltage coefficient (capacitance vs. bias voltage) and ensure that the capacitance is
sufficient to maintain stability and provide sufficient transient response for your application. This can be verified by
checking the output transient response as described in the RT8296 IC datasheet.
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RT8296AHZSP
Evaluation Board
Schematic, Bill of Materials and Board Layout
EVB Schematic Diagram
TP4
BS
D2
VOUT
NF
GND
TP2
SS
FB
NF
75k
5
22uF
22uF
0.1uF
C6
GP3
10uH
C5
L1
0.1uF
C4
EN
GP4
GND
NF
C10
0.1uF
SS
COMP
6
NF
C8
C7
3.3nF
13k
R3
24k
R2
8
GND
R5
C13
3
C11
D1
7
NF
1
R1
SW
TP1
EN
GND
NF
BS
4,9
R4
0.1uF 100k
C3
10uF
C2
C1
10uF
VIN
C12
2
C9
GP1
GP2
TP3
SW
NF
U1 SOP-8(Exposed Pad)
VIN
C1, C2: 10μF/50V/X5R, 1206, TDK C3216X5R1H106K
C4, C5: 22μF/16V/X5R, 1210, Murata GRM32ER61C226K
L1: 10μH TAIYO YUDEN NR8040T100M, DCR=34mΩ
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RT8296AHZSP
Evaluation Board
Bill of Materials
Reference
Qty
Part number
Description
Package
Manufacture
U1
1
RT8296AHZSP
DC-DC Converter
PSOP-8
Richtek
C1, C2
2
C3216X5R1H106K160AB
1206
TDK
C4, C5
2
GRM32ER61C226KE20#
1210
Murata
C7
1
0603B332K500
0603
WALSIN
C3, C6, C10,C11
4
C1608X7R1H104K080AA
0603
TDK
C8,C9,C12,C13
0
L1
1
R1
1
75kΩ/±1%, Resistor
0603
R2
1
24kΩ/±1%, Resistor
0603
R3
1
13kΩ/±1%, Resistor
0603
R4
1
100kΩ/±1%, Resistor
0603
R5
0
Not Installed
0603
D1, D2
0
Not Installed
TP
4
Test Pin
GP
4
Golden Pin
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10uF/±10%/50V/X5R
Ceramic Capacitor
22uF/±10%/16V/X5R
Ceramic Capacitor
3.3nF/±10%/50V/X7R
Ceramic Capacitor
0.1uF/±10%/50V/X7R
Ceramic Capacitor
Not Installed
NR8040T100M
10uH/3.1A/±20%,
DCR=34mΩ, Inductor
0603
8mmx8mmx4mm
TAIYO YUDEN
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RT8296AHZSP
Evaluation Board
EVB Layout
st
Top View (1 layer)
Bottom View (2nd Layer)
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RT8296AHZSP
Evaluation Board
Component Placement Guide—Component Side (1st layer)
PCB Layout—Component Side (1st Layer)
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RT8296AHZSP
Evaluation Board
Component Placement Guide—Bottom Side (2
nd
PCB Layout—Bottom Side (2
nd
layer)
layer)
Other Technical Information
 For more information, please find the related datasheet or application notes from the Richtek website
http://www.richtek.com
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