Anpec APW7208C Schematic [ru]
APW7208
1MHz, High-Efficiency, Step-Up Converter for 2 to 6 White LEDs
Features
• Wide Input Voltage from 2.5V to 6V
• 104mV Reference Voltage
• Fixed 1MHz Switching Frequency
• High Efficiency up to 88%
• 100Hz to 100kHz PWM Brightness Control Fre-
quency
• Open-LED Protection
• Under-Voltage Lockout Protection
• Over-Temperature Protection
• <1µA Quiescent Current During Shutdown
• SOT-23-6 Package
• Lead Free and Green Devices Available
(RoHS Compliant)
Applications
• White LED Display Backlighting
General Description
The APW7208 is a current-mode and fixed frequency
boost converter with an integrated N-FET to drive up to 6
white LEDs in series.
The series connection allows the LED current to be identical for uniform brightness. Its low on-resistance of NFET and feedback voltage reduces power los s and
achieves high efficiency. Fast 1MHz current-mode PWM
operation is available for input and output capacitors and
a small inductor while minimizing ripple on the input
supply. The OVP pin monitors the output voltage and stops
switching if exceeds the over-voltage threshold. An internal soft-start circuit eliminates the inrush current during
start-up.
The APW7208 also integrates under-voltage lockout,
over-temperature protection and current limit circuits.
The APW7208 is available in a SOT-23-6 package.
Pin Configuration
• Cell Phone and Smart Phone
• PDA, PMP, and MP3
LX 1
GND 2
FB 3
6 VIN
5 OVP
4 EN
• Digital Camera
SOT-23-6
(Top View)
Simplified Application Circuit
C2
1µF
V
OUT
Up to 6
WLEDs
R1
5.1Ω
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V
IN
C1
2.2µF
OFF ON
ANPEC reserves the right to make changes to improve reliability or manufacturability without notice, and
advise customers to obtain the latest version of relevant information to verify before placing orders.
Copyright ANPEC Electronics Corp.
Rev. A.4 - Aug., 2009
L1
22µH
6
VIN
2
GND
4
EN
LX
OVP
FB
1
5
3
APW7208
Ordering and Marking Information
APW7208
Assembly Material
Handling Code
Temperature Range
Package Code
APW7208 C :
Note : ANPEC lead-free products contain molding compounds/die attach materials and 100% matte tin plate termination finish; which
are fully compliant with RoHS. ANPEC lead-free products meet or exceed the lead-free requirements of IPC/JEDEC J-STD-020D for
MSL classification at lead-free peak reflow temperature. ANPEC defines “Green” to mean lead-free (RoHS compliant) and halogen
free (Br or Cl does not exceed 900ppm by weight in homogeneous material and total of Br and Cl does not exceed 1500ppm by
weight).
W08X
Package Code
C : SOT-23-6
Operating Ambient Temperature Range
I : -40 to 85 oC
Handling Code
TR : Tape & Reel
Assembly Material
G : Halogen and Lead Free Device
X - Date Code
Absolute Maximum Ratings (Note 1)
Symbol
VIN VIN Supply Voltage (VIN to GND) -0.3 ~ 7 V
FB, EN to GND Voltage -0.3 ~ VIN V
VLX LX to GND Voltage -0.3 ~ 34 V
V
OVP to GND Voltage -0.3 ~ 32 V
OVP
TJ Maximum Junction Temperature 150 °C
T
Storage Temperature -65 ~ 150 °C
STG
T
Maximum Lead Soldering Temperature, 10 Seconds 260 °C
SDR
Note 1: Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are
stress ratings only and functional operation of the device at these or any other conditions beyond those indicated in the operational
sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device
reliability.
Parameter Rating Unit
Thermal Characteristics (Note 2)
Symbol
θJA
Note 2: θJA is measured with the component mounted on a high effective thermal conductivity test board in free air. The exposed pad
of package is soldered directly on the PCB.
Junction to Ambient Thermal Resistance
Parameter Typical Value Unit
(Note 2)
SOT-23-6
250
°C/W
Recommended Operating Conditions (Note 3)
Symbol
VIN VIN Input Voltage 2.5 ~ 6 V
V
Converter Output Voltage Up to 24 V
OUT
CIN Input Capacitor 2.2 or higher
C
Output capacitor 0.47 or higher
OUT
L1 Inductor 6.8 ~ 22
TA Ambient Temperature -40 ~ 85 °C
TJ Junction Temperature -40 ~ 125 °C
Note 3: Refer to the application circuit for further information.
Copyright ANPEC Electronics Corp.
Rev. A.4 - Aug., 2009
Parameter Range Unit
µF
µF
µH
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APW7208
Electrical Characteristics
(Refer to figure 1 in the “Typical Application Circuits”. These specifications apply over VIN = 3.6V, unless otherwise noted. TA = 25°C.)
Symbol
Parameter Test Conditions
APW7208
Min. Typ. Max.
SUPPLY VOLTAGE AND CURRENT
VIN Input Voltage Range TA = -40 ~ 85°C, TJ = -40 ~ 125°C 2.5 - 6 V
I
V
DD1
I
DD2
Input DC bias current
FB = GND, switching - 1 2 mA
ISD
= 0.3V, no switching 70 100 130 µA
FB
EN = GND - - 1 µA
UNDER-VOLTAGE LOCKOUT
UVLO Threshold Voltage VIN Rising 2.2 2.3 2.48 V
UVLO Hysteresis Voltage 50 100 150 mV
REFERENCE AND OUTPUT VOLTAGES
V
Regulated Feedback Voltage TA = 25°C 101 104 107 mV
REF
IFB FB Input Current -50 - 50 nA
INTERNAL POWER SWITCH
FSW Switching Frequency FB=GND 0.8 1.0 1.2 MHz
RON
I
Power Switch On Resistance
Power Switch Current Limit - 1.2 - A
LIM
- 0.6 1.2
LX Leakage Current VEN=0V, VLX=0V or 5V, VIN = 5V -1 - 1 µA
D
LX Maximum Duty Cycle 92 95 98 %
MAX
OUTPUT OVER VOLTAGE PROTECTION
V
Over Voltage Threshold 26 28 30 V
OVP
OVP Hysteresis 1 - 4 V
OVP Leakage Current V
=24V - - 45 µA
OVP
ENABLE AND SHUTDOWN
V
EN Voltage Threshold VEN Rising 0.4 0.7 1 V
TEN
EN Voltage Hysteresis 0.05 0.1 0.15 V
I
EN Leakage Current VEN= 0~5V, VIN = 5V -1 - 1 µ A
LEN
OVER-TEMPERATURE PROTECTION
T
Over-Temperature Protection TJ Rising - 150 - °C
OTP
Over-Temperature Protection
Hysteresis
- 40 - °C
Unit
Ω
Copyright ANPEC Electronics Corp.
www.anpec.com.tw3
Rev. A.4 - Aug., 2009
APW7208
≅
≅
Typical Operating Characteristics
(Refer to figure 1 in the section “Typical Application Circuits”, VIN=3.6V, TA=25oC, 6WLEDs unless otherwise specified)
Efficiency vs. WLED Current
95
90
85
80
75
70
Efficiency (η)
65
60
VIN=3.3V
55
50
0 5 10 15 20 25 30
VIN=3.6V
WLED Current, I
VIN=4.2V
6 WLEDs 19.3V@20mA
(mA)
LED
WLED Current vs. PWM Duty Cycle
20
18
16
14
(mA)
LED
12
10
8
6
WLED Current, I
4
2
0
0 20 40 60 80 100
100Hz
1kHz
PWM Duty Cycle (%)
WLED Current vs. Supply Voltage
21.0
20.8
20.6
20.4
(mA)
LED
20.2
20.0
19.8
19.6
WLED Current, I
19.4
19.2
19.0
2.5 3 3.5 4 4.5 5 5.5 6
Supply Voltage, V
Copyright ANPEC Electronics Corp.
Rev. A.4 - Aug., 2009
IN
η=P
(V)
VIN=5V
OUT/PIN
100kHz
Efficiency vs. WLED Current
95
90
85
80
75
70
Efficiency (η)
65
60
VIN=3.3V
55
50
0 5 10 15 20 25 30
VIN=3.6V
WLED Current, I
VIN=4.2V
4 WLEDs 13V@20mA
(mA)
LED
Switching Frequency vs. Supply
Voltage
1.2
1.1
(MHz)
1
SW
0.9
0.8
0.7
0.6
0.5
Switching Frequency, F
0.4
2.5 3 3.5 4 4.5 5 5.5 6
Supply Voltage, V
(V)
IN
Switch ON Resistance vs. Supply
Voltage
0.7
(Ω)
ON
0.6
0.5
0.4
0.3
0.2
0.1
Switch ON Resistance, R
0
2.5 3 3.5 4 4.5 5 5.5 6
Supply Voltage, V
(V)
IN
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η=P
VIN=5V
OUT/PIN
APW7208
Operating Waveforms
(Refer to the application circuit in the section “Typical Application Circuits”, VIN=3.6V, TA=25oC, 6WLEDs unless otherwise
spec ified)
1
V
IN
2
3
4
CH1: VEN, 2V/Div, DC
CH2: VIN, 2V/Div, DC
CH3: V
OUT
CH4: IIN, 0.1A/Div, DC
Time: 1ms/Div
Start-up
V
EN
V
OUT
IIN, 0.1A/Div
6WLEDs, L=22µH, VIN=3.6V, I
, 10V/Div, DC
Open-LED Protection
LED
=20mA
1
2
3
4
CH1: VEN, 2V/Div, DC
CH2: VIN, 2V/Div, DC
CH3: V
OUT
CH4: IIN, 0.1A/Div, DC
Time: 1ms/Div
Normal Operating Waveform
Start-up
V
V
IN
V
OUT
IIN, 0.1A/Div
4WLEDs, L=22µH, VIN=3.6V, I
, 10V/Div, DC
EN
=20mA
LED
V
, 10V/Div
OUT
1
CH1: V
, 10V/Div, DC
OUT
Time: 20ms/Div
Copyright ANPEC Electronics Corp.
Rev. A.4 - Aug., 2009
1
2
3
6WLEDs, L=22µH, VIN=3.6V, I
CH1: VLX, 20V/Div, DC
CH2: V
, 50mV/Div, AC
OUT
CH3: IL, 0.1A/Div, DC
Time: 1µs/Div
VLX, 20V/Div, DC
V
, 50mV/Div, AC
OUT
IL, 0.1A/Div
=20mA
LED
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