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PDF APW7215 Data sheet ( Hoja de datos )
| Número de pieza | APW7215 | |
| Descripción | Step-Up Converter | |
| Fabricantes | ANPEC | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de APW7215 (archivo pdf) en la parte inferior de esta página. Total 17 Páginas | ||
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APW7215
Fixed 600kHz Step-UP Converter for White LEDs
Features
General Description
• Wide Input Voltage from 2.7V to 6V
• Fixed 600kHz Switching Frequency
• Reference Voltage : 0.2V
• PWM brightness control with wide frequency
range of 5KHz to 100KHz
• Build-in Power MOSFET: 0.3Ω
• Over-Voltage Protection
• Under Voltage Lockout Protection
• Over Temperature Protection
• <1µA Quiescent Current during Shutdown
• TDFN2x2-6 Package
• Halogen and Lead Free Available (RoHS
Compliant)
Applications
The APW7215 is a current-mode and fixed frequency
600kHz boost converter with an integrated N-FET to drive
white LEDs.
The series connection allows the LED current to be iden-
tical for uniform brightness. Its low on-resistance of NFET
and low feedback voltage reduce power loss and achieve
high efficiency. 600kHz Constant switching frequency al-
lows using small-size inductor and both of input and out-
put capacitors. An over voltage protection function, which
monitors the output voltage via LX pin, stops switching of
the IC if the LX voltage exceeds the over voltage threshold.
An internal soft-start circuit eliminates the inrush current
during start-up.
The APW7215 also integrates under-voltage lockout and
over-temperature protection to protect the IC in abnormal
conditions. The APW7215 is available in TDFN2x2-6
package.
• White LED Display Backlighting
• Cell Phone and Smart Phone
• PDA, PMP, MP3
• Digital Camera
Simplified Application Circuit
Pin Configuration
FB 1
NC 2
GND 3
6 VIN
5 EN
4 LX
APW7215
TDFN2x2-6
Top View
VIN
C1
1µF
PWM Dimming
L1
22µ H
VIN LX
GND
EN FB
VOUT
C2
1µ F
10 strings
R1
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.2 - Oct., 2012
1
www.anpec.com.tw
1 page  
APW7215
Typical Operating Characteristics
Vin Input Voltage vs. Efficiency
100.0
90.0
80.0
70.0
60.0
50.0
2.5 3 3.5 4 4.5 5 5.5 6
Vin Input Voltage (V)
Vin Input Voltage vs. LED Current
20.5
20.3
20.1
19.9
19.7
19.5
3
3.25 3.5 3.75 4 4.25 4.5 4.75
Vin Input voltage (V)
5
Vin Input Voltage vs. RON
0.5
0.4
0.3
0.2
0.1
0
2.5 3 3.5 4 4.5 5 5.5 6
Vin Input Voltage (V)
Copyright © ANPEC Electronics Corp.
Rev. A.2 - Oct., 2012
5
EN Dimming Cycle vs. LED Current
21
18
15
12
9
- 5K Hz
6 - 50K Hz
- 100K Hz
3
0
0 10 20 30 40 50 60 70 80 90 100
EN Dimming Cycle (%)
Vin Input Voltage vs. Max Duty Cycle
100
99.5
99
98.5
98
97.5
97
2.5 3 3.5 4 4.5 5 5.5 6 6.5
Vin Input Voltage (V)
EN Dimming cycle vs. Feedback Voltage
200
180
160
140
120
100
80
60
40
20
00
- 5K Hz
- 50K Hz
- 100K Hz
20 40 60 80
EN Dimming cycle (%)
100
www.anpec.com.tw
5 Page 
APW7215
Application Information
Input Capacitor Selection
The input capacitor (C ) reduces the ripple of the input
IN
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 capacitance
is used. For reliable operation, it is recommended to
select the capacitor with maximum voltage rating at least
1.2 times of the maximum input voltage. The capacitors
should be placed close to the VIN and the GND.
Inductor Selection
Selecting an inductor with low dc resistance reduces con-
duction losses and achieves high efficiency. The efficiency
is moderated whilst using small chip inductor which op-
erates with higher inductor core losses. Therefore, it is
necessary to take further consideration while choosing
an adequate inductor. Mainly, the inductor value deter-
mines the inductor ripple current: larger inductor value
results in smaller inductor ripple current and lower con-
duction losses of the converter. However, larger inductor
value generates slower load transient response. A rea-
sonable design rule is to set the ripple current, ∆IL, to be
30% to 50% of the maximum average inductor current,
IL(AVG). The inductor value can be obtained as below,
L
≥
VIN
VOUT
2
×
VOUT − VIN
FSW ⋅ IOUT(MAX)
×
η
∆IL
IL(AVG)
where
V = input voltage
IN
V = output voltage
OUT
F = switching frequency in MHz
SW
IOUT = maximum output current in amp.
= Efficiency
∆IL /IL(AVG) = inductor ripple current/average current
(0.3 to 0.5 typical)
To avoid the saturation of the inductor, the inductor should
be rated at least for the maximum input current of the
converter plus the inductor ripple current. The maximum
input current is calculated as below:
IIN(MAX )
=
IOUT(MAX) ⋅ VOUT
VIN ⋅ η
The peak inductor current is calculated as the following
equation:
( )IPEAK
= IIN(MAX) +
1 ⋅ VIN ⋅ VOUT − VIN
2 VOUT ⋅ L ⋅ FSW
VIN IIN
IL
LX D1 IOUT VOUT
CIN N-FET ISW
ESR
COUT
IL
ILIM
IPEAK
IIN
∆IL
ISW
ID
IOUT
Output Capacitor Selection
The current-mode control scheme of the APW7215 al-
lows the usage of tiny ceramic capacitors. The higher
capacitor value provides good load transients response.
Ceramic capacitors with low ESR values have the lowest
output voltage ripple and are recommended. If required,
tantalum capacitors may be used as well. The output ripple
is the sum of the voltages across the ESR and the ideal
output capacitor.
V =V+V
OUT
ESR
COUT
∆VCOUT
≈
IOUT
COUT
⋅
VOUT
VOUT
− VIN
⋅ FSW
∆VESR ≈ IPEAK ⋅ RESR
where I is the peak inductor current.
PEAK
Copyright © ANPEC Electronics Corp.
Rev. A.2 - Oct., 2012
11
www.anpec.com.tw
11 Page | ||
| Páginas | Total 17 Páginas | |
| PDF Descargar | [ Datasheet APW7215.PDF ] | |
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