ADDTEK AMC7150DL

AMC7150
1.5A POWER LED DRIVER
www.addmtek.com
DESCRIPTION
FEATURES
AMC7150 is a PWM power LED driver IC. The
driving current from few milliamps up to 1.5A. It allows
high brightness power LED operating at high efficiency
from 4Vdc to 40Vdc. Up to 200KHz external controlled
operation frequency. External resistor controlled the
maximum output current to single LED or a LED string.
„
„
„
„
„
„
Only 5 external components required.
Output driving current up to 1.5A.
4V~40V wide operation voltage range.
High efficiency
ESD protection HBM 2KV
TO-252 5-pin power package.
APPLICATIONS
„
„
„
PACKAGE PIN OUT
DC/DC LED driver
Automotive
Lighting
5
OSC
4
OUT
3
GND
2
CS
1
VCC
TO-252-5L (Top View)
TYPICAL APPLICATION
Rsense
4V~40V
VCC
CIN
OSC
Note:
L
OUT
AMC7150
DF
GND
CT
DL
CS
ORDER INFORMATION
TO-252
5-pin
AMC7150DL
AMC7150DLF (Lead Free)
1. All surface-mount packages are available in Tape & Reel. Append the letter “T” to part number (i.e. AMC7150DLT).
2. The letter ”F” is marked for Lead Free process.
Copyright © 2006 ADDtek Corp.
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AMC7150
POWER DISSIPATION TABLE
Package
DL
DLF
θJA
O
( CW)
80
80
TA=70 OC
TA= 85OC
Derating factor ( mW/OC )
TA≦25 OC
TA≧25 OC
Power rating (mW) Power rating (mW) Power rating (mW)
12.5
1560
1000
812
12.5
1560
1000
812
Note :
Junction Temperature Calculation: TJ = TA + (PD x θJA).
PD: Power Dissipation, TA: Ambient temperature, θJA: Thermal Resistance-Junction to Ambient
The θJA numbers are guidelines for the thermal performance of the device/PC-board system.
All of the above assume no ambient airflow.
BLOCK DIAGRAM
Rsense
4V~40V
CS
VCC
OUT
L
330mV
CIN
DF
DRIVER
CONTROL
OSC
OSC
AMC7150
CT
GND
Copyright © 2006 ADDtek Corp.
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AMC7150
PIN DESCRIPTION
Pin Number
Pin Name
Pin Function
1
VCC
Input Voltage 4V ~ 40V
2
CS
Peak current senses pin.
3
GND
Ground
4
OUT
Driver output pin.
5
OSC
Oscillator timing capacitor.
ABSOLUTE MAXIMUM RATINGS
-0.3V to 40V
-0.3V to 40V
150OC
-40OC to 150OC
260OC
Input Voltage, VCC
Output Voltage, OUT
Maximum Junction Temperature , TJ
Storage Temperature Range
Lead Temperature (soldering, 10 seconds)
Note:
Exceeding these ratings could cause damage to the device. All voltages are with respect to Ground.
Currents are positive into, negative out of the specified terminal.
RECOMMENDED OPERATING CONDITIONS
Parameter
Symbol
Min
Typ
Supply Voltage
VCC
4
Output current
IOUT
Operating free-air temperature range
Ta
-40
Max
40
1.5
85
Unit
V
A
℃
ELECTRICAL CHARACTERISTICS
VCC=5V, Ta=25°C. ( Unless otherwise noted)
Parameter
Symbol
Condition
Min
Supply Current
ICC
VCC=4~40V
Output Drop-out Voltage
VDP
IOUT=1A, VCS-VOUT
Output Off Current
IOFF
VCS-VOUT= 40V
Current Sense Voltage
VCS
VCC- VCS
Maximum duty cycle
TDC
VCS=VCC
OSC Charge Current
ICH
Copyright © 2006 ADDtek Corp.
300
3
Typ
Max
Unit
Apply Pin
4
mA
VCC
1
1.31
V
200
300
µA
330
360
mV
85
%
35
uA
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OUT
CS
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AMC7150
APPLICATION INFORMATION
Low Voltage DC/DC Application
The AMC7150 was designed for power LED driving application. Only 5 external components were required for
low voltage application. Fig.1 shows the typical application circuit for input voltage range from 4V to 40V. Buck power
conversion topology was used and total forward voltage (at expecting current) of the LED string should lower than
supply voltage by 1.6V at least.
Rsense
4V~40V
VCC
OSC
CIN
CT
CS
L
OUT
AMC7150
DF
GND
Input Bypass Capacitor
The input by-pass capacitor CIN holds the input voltage and filters out the switching noise of AMC7150.
Flywheel Diode
The fast recovery diode was recommended for flywheel diode DF. This is because the high reverse recovery
current will cause the voltage drop across Rsense being higher than 330mV, and consequently the switch will be turned
off which has just been turned on.
LED Driving Current
The peak current IPK flow though LEDs was decided by:
I PK =
330mV
Rsense
The average current on LEDs was determined by the peak-to-peak ripple current that was decided by inductor L.
Assume the target average current 550mA on LEDs and ripple current 100mA then the Rsense should be:
Rsense =
330mV
= 0.55Ω
550mA + 0.5 ⋅ 100mA
The Rsense value should higher than 200mΩ so that driving current won’t over the recommended maximum driving
current 1.5A.
Copyright © 2006 ADDtek Corp.
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AMC7150
Inductor
The Inductor L stores energy during switch turn-on period and discharge driving current to LEDs via flywheel
diode while switch turn-off. In order to reduce the current ripple on LEDs, the L value should high enough to keep the
system working at continuous-conduction mode that inductor current won’t fall to zero.
Since in steady-state operation the waveform must repeat from one time period to the next, the integral of the
inductor voltage vL over one time period must be zero:
∫
Ts
0
tON
Ts
0
tON
v L dt = ∫ v L dt + ∫ v L dt = 0
Where Ts = t ON + t OFF
Therefore
t ON
VLED + VF
=
t OFF VCC − VRsense − VSAT − VLED
Where, VLED is the total forward voltage (at expecting current) of the LED string, VF is the forward voltage of the
flywheel diode DF, VRsense is the peak value of the voltage drop across Rsense which is 300mV, and VSAT is the saturation
voltage of the switch which has a typical value of 1V.
Since the operation frequency f is determined by choosing appropriate value for timing capacitor CT, the switch
turn-on time can also be known by
t ON = D ⋅ Ts =
D
f
Where
D( Dutycycle) =
t ON
t ON + t OFF
With knowledge of the peak switch current and switch on time, the value of inductance can be calculated.
L=
VCC − VRsense − VSAT − VLED
⋅ t ON
I PK
Copyright © 2006 ADDtek Corp.
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AMC7150
PACKAGE
‧
5-Pin Surface Mount TO-252 ( DL )
Copyright © 2006 ADDtek Corp.
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AMC7150
IMPORTANT NOTICE
ADDtek reserves the right to make changes to its products or to discontinue any integrated circuit product or service
without notice, and advises its customers to obtain the latest version of relevant information to verify, before placing
orders, that the information being relied on is current.
A few applications using integrated circuit products may involve potential risks of death, personal injury, or severe
property or environmental damage. ADDtek integrated circuit products are not designed, intended, authorized, or
warranted to be suitable for use in life-support applications, devices or systems or other critical applications. Use of
ADDtek products in such applications is understood to be fully at the risk of the customer. In order to minimize risks
associated with the customer’s applications, the customer should provide adequate design and operating safeguards.
ADDtek assumes to no liability to customer product design or application support. ADDtek warrants the performance of
its products to the specifications applicable at the time of sale.
ADDtek Corp.
9F, No. 20, Sec. 3, Bade Rd., Taipei, Taiwan, 105
TEL: 2-25700299
FAX: 2-25700196
Copyright © 2006 ADDtek Corp.
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