General Description
The RT4822 is a boost regulator designed to provide a minimum output voltage from a single-cell Li-Ion battery or two alkaline battery series, even when the battery voltage is below system minimum. Quiescent current in shutdown mode is less than 1µA, which maximizes battery life.
Performance Specification Summary
The boost conveter has an input voltage range from 1.8V to 5.5V, and the output voltage range is from 3.15V to 5.5V. It can operate in force bypass mode and boost mode. And the power-on inrush current and current limit are implemented serval setting for difference application. The RT4822 is available in a WL-CSP-9B 1.3x1.2 (BSC) package.
Table 1. RT4822WSC Evaluation Board Performance Specification Summary
Specification
|
Test Conditions
|
Min
|
Typ
|
Max
|
Unit
|
Input Voltage Range
|
|
1.8
|
--
|
5.5
|
V
|
Output Current
|
VIN > 3V, VOUT = 5V
|
0
|
--
|
1.5
|
A
|
Default Output Voltage
|
|
--
|
5
|
--
|
V
|
Operation Frequency
|
|
3
|
3.5
|
4
|
MHz
|
Output Ripple Voltage
|
VIN = 3.6V, VOUT = 5V, IOUT = 0.5A
|
--
|
40
|
--
|
mVp-p
|
Line Regulation
|
IOUT = 0.5A, VIN = 1.8V to 4.8V, VOUT = 5V
|
--
|
±1
|
--
|
%
|
Load Regulation
|
VIN = 3.6V, IOUT = 0.2A to 1A, VOUT = 5V
|
--
|
±1
|
--
|
%
|
Load Transient Response
|
VIN = 3.6V, VOUT = 5V ,IOUT = 50mA to 500mA
|
--
|
±3
|
--
|
%
|
Maximum Efficiency
|
VIN = 3.6V, VOUT = 5V, IOUT = 0.6A
|
--
|
93
|
--
|
%
|
Power-up Procedure
1. Connect input voltage (1.8V < VIN < 5.5V) to VIN pin.
2. Setting BOOST enable selection by CHIP_EN. (setting 0x05[0] by I2C)
3. Setting BOOST pre-charge current and BOOST_LIMIT for power on inrush current. (setting 0x00 by I2C)
4. To enable Boost converter by external EN pin or 0x05[5].
5. To connect an external load to output and verify the output voltage versus applied current.
Output Voltage Setting
The output voltage set by internal register in the following I2C table.
Addr
|
Reg Name
|
Bit
|
Bit Name
|
Default
|
Type
|
Description
|
0x02
|
BOOST_VOUT
|
7
|
Reserved
|
0
|
RW
|
Reserved
|
6:0
|
BOOST_VOUT
|
1101011
|
RW
|
Boost output voltage can be set voltage from 3.15V to 5.5V with 25mV/step.
0000000 to 0100001: 3.15V
…
1101011: 5V (default)
…
1111111: 5.5V
|
Detailed Description of Hardware
Headers Description and Placement
![Technical Document Image Preview](/~/media/Richtek/Design Support/Technical Documentation/UG4822WSC/EN/Version1/image001.png)
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.
Bill of Materials
Reference
|
Count
|
Part Number
|
Description
|
Package
|
Manufacture
|
CN1
|
1
|
CHEB254S006-CF1043
|
I2C
|
|
Cherng Weei
|
C1
|
1
|
EMK325BJ476KM-T
|
47µF/16V/X5R
|
1210
|
TAIYO YUDEN
|
C2
|
1
|
GRM155R60J475ME47
|
4.7µF/6.3V/X5R
|
0402
|
Murata
|
C4
|
1
|
0603X106M6R3CT
|
10µF/6.3V/X5R
|
0603
|
WALSIN
|
L1
|
1
|
DFE252012F-1R0M=P2
|
1.0µH/3.3A
|
2.5x2.0x1.2mm
|
Murata
|
R1, R2
|
2
|
WR06X2201FTL
|
22k/0603
|
0603
|
WALSIN
|
U1
|
1
|
RT4822WSC
|
Step-Up DC-DC Converter
|
WL-CSP-9B 1.3x1.2 (BSC)
|
RICHTEK
|
Typical Applications
EVB Schematic Diagram
![Technical Document Image Preview](/~/media/Richtek/Design Support/Technical Documentation/UG4822WSC/EN/Version1/image002.png)
1. C1 is placed on input side, and the capacitors are design for long wire effect. If input source is close RT4822 then the capacitors are optional.
2. C4 is placed on output side, and the capacitor is optional for output voltage ripple improvement.
Measure Result
Output Ripple Measurement
|
Load Transient Response
|
![Technical Document Image Preview](/~/media/Richtek/Design Support/Technical Documentation/UG4822WSC/EN/Version1/image003.jpg)
|
![Technical Document Image Preview](/~/media/Richtek/Design Support/Technical Documentation/UG4822WSC/EN/Version1/image004.jpg)
|
Power On from EN
|
DVS up
|
![Technical Document Image Preview](/~/media/Richtek/Design Support/Technical Documentation/UG4822WSC/EN/Version1/image005.jpg)
|
![Technical Document Image Preview](/~/media/Richtek/Design Support/Technical Documentation/UG4822WSC/EN/Version1/image006.jpg)
|
Short Circuit Response
|
Sine Waveform Stability
|
![Technical Document Image Preview](/~/media/Richtek/Design Support/Technical Documentation/UG4822WSC/EN/Version1/image007.jpg)
|
![Technical Document Image Preview](/~/media/Richtek/Design Support/Technical Documentation/UG4822WSC/EN/Version1/image008.jpg)
|
Evaluation Board Layout
![一張含有 文字, 電子用品, 螢幕擷取畫面 的圖片
自動產生的描述](/~/media/Richtek/Design Support/Technical Documentation/UG4822WSC/EN/Version1/image009.jpg)
Figure 1. Top View (1st layer)
![Technical Document Image Preview](/~/media/Richtek/Design Support/Technical Documentation/UG4822WSC/EN/Version1/image010.jpg)
Figure 2. PCB Layout—Inner Side (2nd Layer)
![Technical Document Image Preview](/~/media/Richtek/Design Support/Technical Documentation/UG4822WSC/EN/Version1/image011.jpg)
Figure 3. PCB Layout—Inner Side (3rd Layer)
![一張含有 文字, 電子用品 的圖片
自動產生的描述](/~/media/Richtek/Design Support/Technical Documentation/UG4822WSC/EN/Version1/image012.jpg)
Figure 4. Bottom View (4th Layer)