ACE716 - ACE Technology Co., LTD.

ACE716
40V Backlight LED Driver with PWM Direct Dimming
Description
The ACE716 is a high efficiency current‐mode asynchronous, 40V boost converter for LED backlight
driving. Its input voltage ranges from 2.5V to 4.5V and it provides an adjustable constant current output
decided by the Rset connected to ACE716’s FB pin. The LED brightness can also be controlled by a
PWM signal directly set to CE pin, making dimming control very simple.
The ACE716’s switching frequency is set to 600KHz, and it will automatically switch between PFM and
PWM mode based on the load current, thus to enhance the converter efficiency at light load as well as
heavy load.
ACE716 consists of many protection blocks such as UVLO, output voltage over voltage protection, and
thermal protection to keep the chip and load safe under unexpected environment.
Features
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Adjustable Output Voltage, Vfb=0.2V
Output voltage 40V, driving up to 12 LED string
Range of operation input voltage: 2.5 – 4.5V
Output Overvoltage Protection @40V
CE pin PWM direct dimming function
Line regulation: 0.1%/V (typ.)
Load regulation: 10mV (typ.)
High efficiency, up to 90% in driving 10 LEDs
Environment Temperature: ‐20℃~85℃
Application
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Smartphone
7” MID
Portable DVD
TFT LCD bias
Portable LED lighting or torch
Other application need high voltage
Absolute Maximum Ratings
Parameter
Max
Input voltage
5.5V
Package Thermal Resistance
DFN2*2-6L (ΘJC)
20℃/W
DFN2*2-6L (ΘJA)
140℃/W
Operating Junction Temperature (TJ)
125℃
Ambient Temperature (TA)
-20℃ to 85℃
ESD (HBM)
>2000V
Storage Temperature (Ts)
-40℃ to 150℃
Output Voltage (SW pin)
40V
Power Dissipation (SOT-23-6)
400mW
Note: Exceed these limits to damage to the device. Exposure to absolute maximum rating conditions may affect device reliability.
VER 1.3
1
ACE716
40V Backlight LED Driver with PWM Direct Dimming
Typical Application and PIN OUT
ACE716
Packaging Type
DFN2*2-6L
SOT-23-6
6
1
DFN2*2-6L SOT-23-6 Description
5
2
4
3
Function
1
3
FB
2
1
Comp
3
2
GND
Ground
4
6
SW
5
5
CE
6
4
VIN
Power switching node to connect inductor
Chip enable, but a PWM signal with various duty cycle can
directly sent to CE pin to
achieve the backlight dimming
Power input, 1uf input capacitor is recommended
Feedback input with reference voltage set to 0.2V
Compensation pin, to connect a 220nF capacitor to make loop
stable
VER 1.3
2
ACE716
40V Backlight LED Driver with PWM Direct Dimming
Ordering Information
ACE716 XX + H
Halogen - free
Pb - free
KN : DFN2*2-6L
GM : SOT-23-6
Efficiency for Driving 10LEDs
Recommended work conditions
Parameter
Value
Input Voltage Range
2.5~4.5V
Operating Junction Temperature (TJ)
-20℃~125℃
VER 1.3
3
ACE716
40V Backlight LED Driver with PWM Direct Dimming
Block Diagram
Electrical Characteristics (TA=25℃)
Parameter
Symbol
Conditions
Input Voltage Range
VIN
Feedback Voltage
Vref
Vin=3.6V, Vce=Vin
UVLO Voltage
VUVLO
Vin H -->L,Iout=0.5A
Feedback Leakage current
Ifb
Quiescent Current
Iq
Line Regulation
Min
Typ
2.5
0.19
0.2
Max
Units
4.5
V
0.21
V
2.5
V
0.1
0.4
uA
Active, Vfb=1V, No Switching
0.6
1
mA
Shutdown, Vin=3.6V
1
5
uA
LnReg
Vin=2.5V to 4.5V
0.1
Switching Frequency
Fsoc
Vin=Vce=3.6V
Low side Switch Rdson
RdsonH
Isw=200mA
Peak Inductor Current Limit
llimit
Vin=3.6V, Vout=32V
0.8
Toff
CE High to low
2.5
CE pin pulse width to
shutdown
CE PWM dimming frequency
Output Over-Voltage
Protection Protection
Over Temperature Protection
Fpwm_CE
Vovp
Vce=3.6V
TSD
Hystersis=40℃
Ce High Threshold
Vceh
CE Low Threshold
Vcel
450
%/V
600
750
KHz
300
500
mohm
1
1.4
A
ms
10
50
KHz
40
42
V
150
℃
1
1.5
3
V
0.3
V
VER 1.3
4
ACE716
40V Backlight LED Driver with PWM Direct Dimming
Typical Performance Characteristics
(Vin=3.6V, L=22uH, Cin=1uF, Cout=1uF, TA=25℃, unless otherwise stated)
VER 1.3
5
ACE716
40V Backlight LED Driver with PWM Direct Dimming
Typical Performance Characteristics
(Vin=3.6V, L=22uH, Cin=1uF, Cout=1uF, TA=25℃, unless otherwise stated)
Functional Descriptions
Loop Operation
The ACE716 is a high voltage, high‐efficiency, DC‐to‐DC step‐up LED driver, capable of driving up to
10 LEDs. It integrates with a 300mΩ MOSFET, with external schottky diode. It uses a PWM current‐mode
control scheme. An error amplifier integrates error between the FB signal and the internal reference
voltage. The output of the integrator is then compared to the sum of a current‐sense signal and the slope
compensation ramp. This operation generates a PWM signal that modulates the duty cycle of the power
MOSFETs to achieve regulation for output voltage.
Current Limit
There is a cycle‐by‐cycle current limit on the high‐side MOSFET of 1A(typ). When the current flowing
out of SW exceeds this limit, the low‐side MOSFET turns off and the external schottky diode rectifier turns
on. Unlike the traditional method of current limiting by limiting the voltage at the external compensation
node, which usually has large variation due to duty cycle variance, this type of peak current limiting
scheme provides a relatively more accurate limit for output current, thereby lowering the requirements for
system design.
Light Load Operation
Traditionally, a fixed current mode constant frequency PWM DC‐DC regulator always switches even
when the output load is small. When energy is shuffling back and forth through the power MOSFETs,
power is lost due to the finite RDSONs of the MOSFETs and parasitic capacitances. At light load, this loss
is prominent and efficiency is therefore very low. ACE716 employs a proprietary control scheme that
improves efficiency in this situation by enabling the device into a power save mode during light load,
thereby extending the range of high efficiency operation.
Pwm Brightness Dimming Control at CE Pin
When CE pin is forced a PWM signal with frequency higher than 5KHz, the chip is in dimming mode. The
internal circuit changes the feedback voltage according to the duty cycle of the PWM signal. The
feedback voltage (Vfb) is simply defined as below:
Vfb=200mV x Duty Cycle (%)
To shut down the chip, one has to make the CE signal low, and keep its low state for more than 2.5ms.
VER 1.3
6
ACE716
40V Backlight LED Driver with PWM Direct Dimming
Packing Information
DFN2*2-6L
VER 1.3
7
ACE716
40V Backlight LED Driver with PWM Direct Dimming
Packing Information
SOT-23-6
VER 1.3
8
ACE716
40V Backlight LED Driver with PWM Direct Dimming
Notes
ACE does not assume any responsibility for use as critical components in life support devices or systems
without the express written approval of the president and general counsel of ACE Electronics Co., LTD.
As sued herein:
1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant
into the body, or (b) support or sustain life, and shoes failure to perform when properly used in
accordance with instructions for use provided in the labeling, can be reasonably expected to result in
a significant injury to the user.
2. A critical component is any component of a life support device or system whose failure to perform can
be reasonably expected to cause the failure of the life support device or system, or to affect its safety
or effectiveness.
ACE Technology Co., LTD.
http://www.ace-ele.com/
VER 1.3
9