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
5.1
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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
Copyright ANPEC Electronics Corp.
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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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APW7208
Σ
Pin Description
PIN
NO. NAME
1 LX Switch pin. Connect this pin to inductor/diode here. 2 GND Power and signal ground pin.
3 FB
4 EN
5 OVP Over-Voltage Protection pin. OVP is connected to the output capacitor of the converter. 6 VIN
Feedback Pin. Reference voltage is 104mV. Connect this pin to cathode of the lowest LED and resistor (R1). Calculate resistor value according to R1=104mV/I
Enable Control Input. Forcing this pin above 1.0V enables the device, or forcing this pin below 0.4V to shut it down. In shutdown, all functions are disabled to decrease the supply current below 1µA. Do not leave this pin floating.
Main Supply Pin. Must be closely decoupled to the GND with a 2.2µF or greater ceramic capacitor.
FUNCTION
LED
.
Block Diagram
VIN
EN
UVLO
OVP
GND
Over-
Temperature
Protection
Slope
Compensation
Oscillator
Soft­Start
Control Logic
Current
Limit
ICMP
COMP
Gate Driver
Current Sense
Amplifier
Error
Amplifier
EAMP
V
REF
104mV
LX
FB
Copyright ANPEC Electronics Corp. Rev. A.4 - Aug., 2009
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APW7208
Typical Application Circuits
V
IN
C1
2.2µF
OFF ON
L1
22µH
6
VIN
2
GND
APW7208
4
EN
LX
OVP
FB
1
5
3
Figure 1. Typical 6 WLEDs
Application
V
IN
C1
2.2µF
OFF ON
PWM
brightness
control
V
C2 1µF
Up to 6 WLEDs
R1
5.1
L1
22µH
6
VIN
2
GND
APW7208
4
EN
3.3V
Duty=100%, LED off Duty=0%, I
LED
=20mA
OUT
100Hz~100kHz
Duty=100%, I Duty=0%, LED off
1
LX
5
OVP
3
FB
V
ADJ
0V
V
IN
L1
22µH
C1
2.2µF
LED
=20mA
6
VIN
2
GND
APW7208
4
EN
LX
OVP
FB
1
5
3
Figure 2. Brightness control using a PWM signal applies to EN
V
OUT
C2 1µF
Up to 6 WLEDs
R4
10K
R3
100K
C3
0.1µF
R2
3.2K
R1
5.1
C2 1µF
V
Up to 6 WLEDs
R1
5.1
OUT
V2R
=
REF
1V
+
1R
=
I
Figure 3. Brightness control using a filtered PWM signal
V
IN
4.5V~6V
C1
10µF
OFF ON
6
2
4
Figure 4. Circuit for driving 27 WLEDs
Copyright ANPEC Electronics Corp. Rev. A.4 - Aug., 2009
2R
 
MAX,LED
VIN
GND
APW7208
EN
V
3R2R3R
L1
10µH
MIN,ADJREF
LX
OVP
FB
V3RIV3RI
+
MAX,ADJMIN,LEDMIN,ADJMAX,LED
IVIVIVIV
+
MAX,LEDREFMIN,LEDMIN,ADJMIN,LEDREFMAX,LEDMAX,ADJ
V
OUT
1
C2
10µF
9 Strings total
5
3
R2
R1
1.1
1.1
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APW7208
Function Description
Main Control Loop
and ground al-
OUT
lows the EAMP to receive an output feedback voltage V at FB pin. When the load current increases, it causes a slightly decrease in VFB relative to the 104mV reference, which in turn causes the COMP voltage to increase until the average inductor c urrent matches the new load current.
VIN Under-Voltage Lockout (UVLO)
Soft-Start
COMP
.
Current-Limit Protection
Over-Temperature Protection (OTP)
The over-temperature circuit limits the junction tempera­ture of the APW7208. When the junction temperature ex­ceeds 150οC, a thermal sensor turns off the power MOSFET, allowing the devices to cool. The thermal sen­sor allows the converters to start a soft-start process and to regulate the output voltage again after the junction tem­perature cools by 40οC. The OTP is designed with a 40οC hysteresis to lower the average Junction Temperature (TJ) during continuous thermal overload conditions, in­creasing the lifetime of the device.
FB
Enable/Shutdown
Open-LED Protection
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APW7208
(
)
Application Information
Input Capacitor Selection
The input capacitor (CIN) reduces the ripple of the input current drawn from the input supply and reduces noise injection into the IC. The reflected ripple voltage will be smaller when an input capacitor with larger c apacitance is used. For reliable operation, it is recommended to select the capacitor with maximum voltage rating at least
Inductor Selection
Selecting an inductor with low dc resistance reduces con­duction losses and achieves high efficiency. The efficiency is moderated while using small chip inductor which op­erates with higher inductor core losses. Therefore, it is necessary to take further consideration while choosing an adequate inductor. Mainly, the inductor value deter­mines the inductor ripple current: larger inductor value results in smaller inductor ripple current and lower c on­duction losses of the converter. However, larger inductor value generates slower load transient response. A rea­sonable design rule is to set the ripple current, ∆IL, to be 30% to 50% of the maximum average inductor current, I
. The inductor value can be obtained as below,
L(AVG)
2
V
IN
L
 
×
V
OUT
VV
INOUT
IF
η
×
)MAX(OUTSW
I
L
I
( )
AVGL
where
VIN = input voltage V
= output voltage
OUT
FSW = switching frequency in MHz I
= maximum output current in amp.
OUT
η = Efficiency ∆IL /I
= inductor ripple current/average current
L(AVG)
(0.3 to 0.5 typical) To avoid the saturation of the inductor, the inductor should
VI
=
I
)MAX(IN
OUT)MAX(OUT
η⋅
V
IN
VVV21
LX
INOUTIN
FLV
SWOUT
D1
I
SW
I
PEAK
I
V
OUT
OUT
ESR
C
OUT
I
LIM
I
L
I
IN
I
OUT
II
V
I
IN
IN
C
IN
I
L
I
SW
I
D
+=
)MAX(INPEAK
I
L
N-FET
Output Capacitor Selection
ΔV
where I
= ΔV
OUT
V
COUT
is the peak inductor current.
PEAK
+ ΔV
ESR
I
OUT
C
OUT
RIV
COUT
 
 
ESRPEAKESR
VV
INOUT
FV
SWOUT
Copyright ANPEC Electronics Corp.
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Rev. A.4 - Aug., 2009
APW7208
Recommended
Inductor
Selection
Application Information (Cont.)
Output Capacitor Selection (Cont.)
. When choosing the input and
COUT
Diode Selection
Setting the LED Current
), flowing via the LEDs and the R1, is cal-
LED
culated by the following equation: I
= 104mV/R1
LED
Designator Manufacturer
L1 GOTREND
Part Number Inductance (µH) Max DCR (ohm)
GTSD-32-220 22 0.592 0.52 3.85 x 3.85 x 1.8
Saturation
Current (A)
Recommended Capacitor Selection
Designator Manufacturer
C1 Murata GRM188C70J225KE20 C2 Murata GRM21BR71H105KA12
Part Number Capacitance (µF)
2.2 X7S 6.3 0603
1.0 X7R 50 0805
TC Code Rated Voltage (V)
Recommended Diode Selection
Designator Manufacturer
D1 Zowie MSCD104 1.0 40 0805
Part Number
Maximum average forward
rectified current (A)
Maximum repetitive peak
reverse voltage (V)
Dimensions
L x W x H (mm3)
Case size
Case size
Layout Consideration
Copyright ANPEC Electronics Corp. Rev. A.4 - Aug., 2009
To Anode of
WLEDs
From Cathod
of WLEDs
Via To OVP
V
OUT
R1
D1
C2
R2
Refer to Fig. 3
LX
L1
C1
R4
R3
C3
Optimized APW7208 Layout
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V
IN
Via To V
Via To GND
OUT
V
EN
V
ADJ
APW7208
Pack age Information
SOT-23-6
D
e
b c
e1
SEE
VIEW A
E1
E
A2A1
A
L
VIEW A
0.25
GAUGE PLANE
SEATING PLANE
0
0.15
0.50
0.22
1.80
0.60 8
SOT-23-6
MIN.
0.000
0.035
0.012
0.003
0.106
0.102
0.055
0.012 0
INCHES
MAX.
0.057
0.006
0.051
0.020
0.009
0.122
0.118
0.071
0.037 BSC
0.075 BSC
0.024
S Y M B O L
A A1 A2
b
c
D
E
E1
e e1
L
0
Note : 1. Follow JEDEC TO-178 AB.
2. Dimension D and E1 do not include mold flash, protrusions or gate burrs. Mold flash, protrusion or gate burrs shall not exceed 10 mil per side.
MILLIMETERS
MIN.
0.00
0.90
0.30
0.08
2.70
2.60 3.00
1.40
0.95 BSC
1.90 BSC
0.30 0
MAX.
1.45
1.30
3.10
8
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APW7208
Carrier Tape & R eel Dimensions
OD0
B0
P0
P2
P1
A
E1
F
W
Application
SOT-23-6
K0
SECTION A-A
B
A
H
A0
SECTION B-B
OD1
B
T
A
d
T1
A H T1 C d D W E1 F
178.0±2.00 50 MIN.
8.4+2.00
-0.00
13.0+0.50
-0.20
1.5 MIN. 20.2 MIN. 8.0±0.30 1.75±0.10 3.5±0.05
P0 P1 P2 D0 D1 T A0 B0 K0
4.0±0.10 4.0±0.10 2.0±0.05
1.5+0.10
-0.00
1.0 MIN.
0.6+0.00
-0.40
3.20±0.20 3.10±0.20 1.50±0.20
Devices Per Unit
Package Type Unit Quantity
SOT-23-6
Copyright ANPEC Electronics Corp. Rev. A.4 - Aug., 2009
(mm)
Tape & Reel 3000
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APW7208
Taping Direction Information
SOT-23-6
USER DIRECTION OF FEED
AAAX AAAX AAAX AAAX AAAX AAAX AAAX
Classification Profile
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APW7208
Classification Reflow Profiles
Profile Feature Sn-Pb Eutectic Assembly Pb-Free Assembly
Preheat & Soak
Temperature min (T Temperature max (T Time (T
smin
to T
smax
smin
smax
) (ts)
)
)
Average ramp-up rate (T
to TP)
smax
Liquidous temperature (TL) Time at liquidous (tL)
Peak package body Temperature (Tp)*
Time (tP)** within 5°C of the specified classification temperature (Tc)
Average ramp-down rate (Tp to T
smax
Time 25°C to peak temperature
See Classification Temp in table 1 See Classification Temp in table 2
)
100 °C 150 °C
60-120 seconds
150 °C 200 °C
60-120 seconds
3 °C/second max. 3°C/second max.
183 °C
60-150 seconds
217 °C
60-150 seconds
20** seconds 30** seconds
6 °C/second max. 6 °C/second max.
6 minutes max. 8 minutes max.
* Tolerance for peak profile Temperature (Tp) is defined as a supplier minimum and a user maximum.
** Tolerance for time at peak profile temperature (tp) is defined as a supplier minimum and a user maximum.
Table 1. SnPb Eutectic Process – Classification Temperatures (Tc)
Package
Thickness
<2.5 mm
Volume mm
3
Volume mm
<350
235 °C 220 °C
350
3
2.5 mm 220 °C 220 °C
Table 2. Pb-free Process – Classification Temperatures (Tc)
Package
Thickness
<1.6 mm
1.6 mm – 2.5 mm
Volume mm3
<350
Volume mm3
350-2000
Volume mm3
260 °C 260 °C 260 °C 260 °C 250 °C 245 °C
>2000
2.5 mm 250 °C 245 °C 245 °C
Reliability Test Program
Test item Method Description
SOLDERABILITY JESD-22, B102 HOLT JESD-22, A108 PCT JESD-22, A102 TCT JESD-22, A104 HBM MIL-STD-883-3015.7 MM JESD-22, A115 Latch-Up JESD 78
Copyright ANPEC Electronics Corp. Rev. A.4 - Aug., 2009
5 Sec, 245°C 1000 Hrs, Bias @ 125°C 168 Hrs, 100%RH, 2atm, 121°C 500 Cycles, -65°C~150°C VHBM2KV VMM200V 10ms, 1tr≧100mA
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APW7208
Customer Service
Anpec Electronics Corp.
Head Office :
No.6, Dusing 1st Road, SBIP, Hsin-Chu, Taiwan, R.O.C. Tel : 886-3-5642000 Fax : 886-3-5642050
Taipei Branch :
2F, No. 11, Lane 218, Sec 2 Jhongsing Rd., Sindian City, Taipei County 23146, Taiwan Tel : 886-2-2910-3838 Fax : 886-2-2917-3838
Copyright ANPEC Electronics Corp. Rev. A.4 - Aug., 2009
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