XU5202
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Dual High-Efficiency PWM Step-Down DC/DC Converter
GENERAL DESCRIPTION
The XU5202 is a dual high-efficiency PWM step-down DC-DC converter. It is capable of delivering 1A output each channel over a wide input voltage from 2.5V to 5.5V, the XU5202 is ideally suited for portable electronic devices that are powered from 1-cell Li-ion battery or from other power sources within the range such as cellular phones, PDAs and other handheld devices. The switching ripple is easily smoothed-out by small package filtering elements due to a fixed operation frequency of 1.5MHz. This along with small DFN-12L 3X3 package provides small PCB area application. Other features include soft start, lower internal reference voltage with 2% accuracy, over temperature protection, and over current protection.
FEATURES FOR EACH CHANNEL
• 1A Output Current
• High Efficiency up to 95% • 2.5V to 5.5V Input Range • Low Quiescent Current 130uA • Adjustable Output from 0.6V to VIN • No Schottky Diode Required
• 1.5MHz Constant Frequency Operation • Low Dropout Operation: 100% Duty Cycle
• Small 12-Lead WDFN Package
• RoHS Compliant and 100% Lead(Pb)-Free
APPLICATIONS
• Personal Information Appliances • Mobile Phones
• Wireless and DSL Modems • Portable Instruments
Figure 1. Typical Application Circuit for Adjustable Version
XU5202
____________________________________________________________________________________________________________________________ ORDERING INFORMATION
PART NUMBER XU5202
TEMP RANGE -40°C to 85°C
SWICHING FREQUENCY1.5MHz
OUTPUT VOLTAGE (V)Adjustable
OUTPUT CURRENT (A)
1
PACKAG
E DFN
PINS 12
PIN CONFIGURATION
Figure 2. PIN Configuration
PIN DESCRIPTION
PIN NUMBER
1 2
3,9,
13(Exposed-Pad)
4 6 7 8 10 12
PIN NAME VIN2 LX2 GND FB1 EN1 VIN1 LX1 FB2 EN2
Power Input of Channel 2. Pin for Switching of Channel 2.
Ground. The exposed pad must be soldered to a large PCB and connected to GND for maximum power dissipation. Feedback of Channel 1.
Enable of Channel 1(Active High). Power Input of Channel 1. Pin for Switch of Channel 1. Feedback of Channel 2
Enable of Channel 2(Active High).
PIN DESCRIPTION
5,11 NC1,NC2 No Connection
XU5202
____________________________________________________________________________________________________________________________ ABSOLUTE MAXIMUM RATINGS
(Note: Do not exceed these limits to prevent damage to the device. Exposure to absolute maximum rating conditions for long periods may affect device reliability.) Supply Voltage VIN1 FB, EN Voltage
LX Voltage
Operating Ambient Temperature Maximum Junction Temperature Storage Temperature
Lead Temperature (Soldering, 10 sec) Power Dissipation
-0.3 to 6.0 -0.3 to VIN+0.3 -0.3 to VIN+0.3 -40 to 85 125 -65 to 150 300 1.667
V V V °C °C °C °C W
PARAMETER VALUE UNIT ELECTRICAL CHARACTERISTICS
(For each output channel, VIN = 3.6V, VREF =0.6V, L=2.2uH, CIN = 2.2uH, VOUT =10uF, TA= 25°C unless otherwise specified)
PARAMETER SYMBOL CHANNEL 1 AND CHANNEL 2
TEST CONDITIONS
MIN TYP MAXUNIT
Input Voltage Range UVLO Threshold Operating Supply Current
VIN VUVLO
VHYSTERESIS =100mV
VFB =0.5V or VOUT =90%, ILoad =0
2.5 5.5 V 2.3
2.45 130 0.1
2.5 V 170
µA1
ISUPPLY
Shutdown Supply Current
VEN =0V, VIN =4.2V Ta =25°C
Regulated Feedback Voltage
VFB
0< Ta <85°C -40°C < Ta <85°C
Reference Voltage Line
Regulation
Regulated Output Voltage Peak Inductor Current
0.588 0.6 0.6120.5865 0.6 0.61350.585 0.6 0.615
0.04
0.4
% V V
VIN =2.7V to 5.5V VOUT =1.8V; IOUT =100mA
VIN =3V, VFB =0.5V or VOUT =90%,Duty Cycle<35%
VFB=0.6V or VOUT =100%
VOUT IPEAK
1.746 1.8 1.854
3 A 1.2 1.5 1.8 MHz
220 0.15
0.3
KHzOhm
Oscillator Frequency FOSC
VFB=0 or VOUT =0
Rds(ON) of P-channel FET ISW =100mA
XU5202
____________________________________________________________________________________________________________________________
Rds(ON) of N-channel FET Enable Threshold Enable Leakage Current LX Leakage Current Maximum Duty Cycle
ISW =-100mA VIN = 2.5V to 5.5V
VEN = 0V, VSW = 0V or 5V, VIN = 5V
0.3 -0.1 -1
0.15 1
0.3 1.5 0.1
OhmV µA
1 uA 100 %
FUNCTION BLOCK DIAGRAM
Figure 3. Functional Block Diagram
APPLICATION INFORMATION
INDUCTOR SELECTION
In normal operation, the inductor maintains
continuous current to the output. The inductor current has a ripple that is dependent on the inductance value. The high inductance reduces the ripple current. In general, select the inductance by the following equation:
L=
VOUT×(VIN−VOUT)VIN⋅f⋅VI
Where VOUTis the output voltage, VIN is the input voltage, f is the switch frequency, and VIis the peak-to-peak inductor ripple current. Typically,
XU5202
____________________________________________________________________________________________________________________________
choose VIas the 30% of the maximum output current.
Manufacturer
be placed as close as possible to VIN and GND.
OUTPUT CAPACITOR SELECTION
A low ESR output capacitor is required in order to maintain low output voltage ripple. In the case of ceramic output capacitors, capacitor ESR is very small and does not contribute to the ripple, so a lower capacitance value is acceptable when ceramic capacitors are used. A 10uF ceramic output capacitor is suitable for most applications.
Part InducDRC Dimensions Number tance(max L*W*H(mm3)
uH) (Ohms)
3.2*2.5*1.7
2.2 0.09 4.7 0.15 Murata LQH32PN Sumida CDRH3D
16
2.2 0.07 4*4*1.8 4.7 0.16 OUTPUT VOLTAGE PROGRAMMING
In the adjustable version, the output voltage is set by a resistive divider according to the following equation:
Table 1. Recommend Surface Mount Inductors
INPUT CAPACITOR SELECTION
The input capacitor reduces input voltage ripple to the converter, low ESR ceramic capacitor is highly recommended. For most applications, a 4.7uF capacitor is used. The input capacitor should
⎛V⎞
R2=R1×⎜OUT−1⎟
⎝0.6⎠
Typically choose R1=100K and determine R2 from
the following equation:
Connect a small capacitor across R1 feed forward capacitance at the FB pin for better performance.
Figure 4. Typical Application Circuit for Adjustable Version
XU5202
____________________________________________________________________________________________________________________________ TYPICAL PERFORMANCE CHARACTERISTICS
(VIN=VEN=3.6V, L=2.2uH, CIN=4.7uF, COUT=10uF)
Efficiency vs. Output Current
Oscillator Frequency vs. Temperature
Reference Voltage vs. Temperature
Steady State Waveform
Vin=5.0VVout=1.8VIout=1AVOUT10mV/DIVSW5V/DIVIL1A/DIV400ns/DIVLoad Transient Waveform
Vin=3.6VVout=1.8VVOUTIout=200-600mA50mV/DIVILOAD500mA/DIVIL500mA/DIV100us/DIV
Startup through Enable Waveform
Vin=3.6VVout=1.8VIout=700mAVOUT1V/DIVEN5V/DIV40us/DIV XU5202
____________________________________________________________________________________________________________________________ PACKAGE OUTLINE
DFN12 3MM X 3MM PACKAGE OUTLINE AND DIMENSIONS
DETAIL A
PIN #1 ID and Tie Bar Mark Options
DIMENSION
SYMB
IN
DIMENSION
OL
MILIMETERS IN INCHES
MIN
MAX MIN MAXA 0.7000.800 0.028 0.031A1 0.0000.050 0.000 0.002A3 0.1750.250 0.007 0.010b 0.1500.250 0.006 0.010D 2.9503.050 0.116 0.120D2 2.3002.650 0.091 0.104E 2.9503.050 0.116 0.120E2 1.4001.750 0.055 0.069e 0.450 0.018 L 0.0350.450 0.014 0.018
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