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FL7701 の電気的特性と機能
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FL7701のメーカーはFairchild Semiconductorです、この部品の機能は「Smart LED Lamp Driver IC」です。 |
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製品の詳細 ( Datasheet PDF )
| 部品番号 FL7701 |
| 部品説明 Smart LED Lamp Driver IC |
| メーカ Fairchild Semiconductor |
ロゴ |
このページの下部にプレビューとFL7701ダウンロード（pdfファイル）リンクがあります。 Total 13 pages |
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June 2013
FL7701
Smart LED Lamp Driver IC with PFC Function
Features
Digitally Implemented Active PFC Function
(No Additional Circuit Necessary for High PF)
Built-in HV Supplying Circuit: Self Biasing
Application Input Range: 80 VAC ~ 308 VAC
AOCP Function with Auto-Restart Mode
Built-in Over-Temperature Protection Function
Cycle-by-Cycle Current Limit
Current-Sense Pin Open Protection
Low Operating Current: 0.85 mA (Typical)
Under-Voltage Lockout with 5 V Hysteresis
Programmable Oscillation Frequency
Programmable LED Current
Analog Dimming Function
Soft-Start Function
Precise Internal Reference: ±3%
Applications
LED Lamp for Decorative Lighting
LED Lamp for Low-Power Lighting
Description
The FL7701 LED lamp driver is a simple IC with PFC
function. The special “adopted digital” technique of the
IC can automatically detect input voltage condition and
send an internal reference signal for achieving high
power factor. When AC input is applied to the IC, PFC
function is automatically enabled. Otherwise, when DC
input is applied to the IC, PFC function is automatically
disabled. The FL7701 does not need a bulk capacitor
(electrolytic capacitor) for supply rail stability, which can
significantly affect to LED lamp system.
Related Resources
Evaluation Board: FEBFL7701_L30U003A
Ordering Information
Part Number
Operating
Temperature Range
FL7701MX
-40°C to +125°C
Package
Packing Method
8-Lead, Small Outline Integrated Circuit (SOIC),
JEDEC MS-012, .150-inch Narrow Body
Tape & Reel
© 2011 Fairchild Semiconductor Corporation
FL7701 • Rev. 1.0.4
www.fairchildsemi.com
1 Page
Pin Configuration
CS
OUT
VCC
RT
HV
NV
GND
ADIM
Figure 3. Pin Configuration
Pin Definitions
Pin #
1
2
3
4
5
6
7
8
Name
CS
OUT
VCC
RT
ADIM
GND
NC
HV
Description
Current Sense. Limits output current depending on the sensing resistor voltage. The CS pin is
also used to set the LED current regulation
OUT. Connects to the MOSFET gate.
VCC. Supply pin for stable IC operation ZCD signal detection used for accurate PFC function.
RT. Programmable operating frequency using external resistor and the IC has pre-fixed
frequency when this pin is open or floating.
Analog Dimming. Connect to the internal current source and can change the output current
using an external resistor. If ADIM is not used, it is recommended to connect a 0.1 µF bypass
capacitor between the ADIM and GND.
GROUND. Ground for the IC.
No Connection
High Voltage. Connect to the high voltage line and supply current to the IC
© 2011 Fairchild Semiconductor Corporation
FL7701 • Rev. 1.0.4
3
www.fairchildsemi.com
3Pages
Functional Description
The FL7701 is a basic PWM controller for buck
converter topology in Continuous Conduction Mode
(CCM) with intelligent PFC function using a digital
control algorithm. The FL7701 has an internal self-
biasing circuit that uses the high-voltage switching
device. The IC does not need an auxiliary powering
path to the VCC pin typical in flyback control ICs or PSR
product family.
When the input voltage applied to the HV pin is over
25 V to 500 V, the FL7701 maintains a 15.5 V DC
voltage at the VCC pin for stable operation. The FL7701
has UVLO block functions such that when the VCC
voltage rises higher than VCCST+, the internal UVLO
block releases and starts operation. Otherwise the VCC
goes down to the VCCST- and IC operation stops.
Normally, the hysteresis function provides stable
operation even if the input voltage is operating under
the very noisy or unstable circumstances.
The FL7701 has a smart internal digital block for
determining input condition: AC or DC. When an AC
source with 50 Hz or 60 Hz is applied to the IC, the IC
automatically changes its internal reference signal,
which is similar to input signal, for creating high power
factor. Otherwise, once the DC source connects to the
IC, the internal reference immediately changes to DC.
1. Soft-Start Function
The FL7701 has an internal soft-start function to reduce
inrush current at startup. When the IC starts operation
following an internal sequence, the internal reference
slowly increases for a pre-determined fixed time. After
this transient period, the internal reference goes to a
steady-state level. In this time, the IC continually tries to
find phase information from the VCC pin. If the IC
succeeds in getting phase information, it automatically
follows a similar shape reference made during the
transient times, 7 periods. If not, the IC has a DC
reference level.
Vbridge
ILED
power for the IC, has voltage ripple as well as the
rectification voltage after bridge, changing voltage level
according to the VCC capacitor value. Using this kind of
voltage fluctuation on the VCC pin, the IC can detect
the time reference and create the internal ZCD signal.
For precise and reliable internal reference for input
voltage signal, the FL7701 uses a digital technique
(sigma/delta modulation) and creates a new internal
signal (DAC_OUT) that has the same phase as the
input voltage, as shown in Figure 5. This signal enters
the final comparator and is compared with current
information from the sensing resistor.
Vbridge
Bridge Diode
Output Voltage
VCC
ZCD
DAC_OUT
Input Voltage
Peak
JFET Output
Voltage
Vdd Charging Voltage
JFET Output Voltage
t
t
t
Figure 5. Internal PFC Function
t
3. Self-Biasing Function
The self-biasing function, using an HV device, can
supply enough operating current to the IC and
guarantee similar startup time across the whole input
voltage range (80 V~308 VAC). However, self-biasing
has a weakness in high-voltage condition. Normally,
the HV device acts as constant current source, so the
internal HV device has power loss when high input
voltage connects to the HV pin. This power loss is
proportional to input voltage. To reduce this power
loss, one of the possible solutions is an additional
resistor between the input voltage source and the HV
pin, as shown in Figure 6.
Bridge
Diode
EMI filter
T/2 = 1/(Input Frequency * 2)
7*(T/2)
Normal Operation
Figure 4. Soft Starting Function in AC Input Mode
2. Internal PFC Function: How to Achieve
High Power Factor
The FL7701 has a simple, but smart, internal PFC
function that does not require additional detection pins
for detecting input phase information or an electrolytic
capacitor for supply voltage stabilization. For achieving
high PF, the FL7701 does not use the rectification
capacitor after the bridge diode. This is important
because the IC instead uses fluctuation in the signal on
the VCC pin. Basically, the VCC pin, which is supplies
© 2011 Fairchild Semiconductor Corporation
FL7701 • Rev. 1.0.4
6
U1
HV
ADIM
RT
VCC
OUT
CS
GND
Figure 6. High-Voltage Application
www.fairchildsemi.com
6 Page
合計 : 13 ページ |
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| 部品番号 | 部品説明 | メーカ |
| FL7701 | Smart LED Lamp Driver IC | Fairchild Semiconductor |
| FL7701MX | Smart LED Lamp Driver IC | Fairchild Semiconductor |