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PDF FL7734MX Data sheet ( Hoja de datos )

Número de pieza FL7734MX
Descripción Single-Stage Primary-Side-Regulation PWM Controller
Fabricantes Fairchild Semiconductor 
Logotipo Fairchild Semiconductor Logotipo



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No Preview Available ! FL7734MX Hoja de datos, Descripción, Manual

November 2014
FL7734
Single-Stage Primary-Side-Regulation PWM Controller
for PFC and Phase Cut Dimmable LED Driving
Features
Excellent Dimmer Compatibility by Active Dimming
Control
Programmable Dimming Curve and Input Current
Management
Constant LED Current Regulation in Large Phase
Angle Range
Cost-Effective Solution without Input Bulk Capacitor
and Feedback Circuitry
Accurate Constant-Current (CC) Control,
Independent on Line Voltage, Output Voltage,
Magnetizing Inductance Variation
Power Factor Correction (PFC)
Fast Startup utilizing Bleeding Circuit
Open-LED Protection
Short-LED Protection
Sensing Resistor Short Protection
Cycle-by-Cycle Current Limiting
Over-Temperature Protection with Auto Restart
Applications
LED Lighting System
Description
The FL7734 is a highly integrated PWM controller with
advanced Primary-Side-Regulation (PSR) technique to
minimize components for low power LED lighting
solutions. Using the innovative TRUECURRENT®
technology for tight constant-current control, it enables
designs with constant-current (CC) tolerance of less
than ±1% in the wide line voltage range to meet
stringent LED brightness requirements.
FL7734 can operate with all types of phase cut
dimmers. Phase cut dimming is managed smoothly by
Fairchilds proprietary constant input current control and
bleeding current control to achieve excellent dimmer
compatibility without visible flicker.
The controller can automatically detect whether there is
a dimmer connection. In non dimming mode, the
operating mode is set to optimize power factor and THD
by enabling linear frequency control and voltage mode
based on DCM.
An external high-voltage bleeding circuit is utilized to
implement fast startup and high system efficiency. The
FL7734 also provides powerful protections, such as
LED open / short, sensing resistor shorted, and over-
temperature for high system reliability. The FL7734 is
available in 16-pin Small-Outline Package (SOP).
Related Resources
FL7734 Product Folder
Ordering Information
Part Number Operating Temperature Range
Package
FL7734MX
-40°C to +125°C
16-Lead, Small Outline Package (SOP-16)
Packing
Method
Tape & Reel
© 2014 Fairchild Semiconductor Corporation
FL7734 • Rev. 1.0
www.fairchildsemi.com

1 page




FL7734MX pdf
Electrical Characteristics
VDD=20 V and TJ=-40 ~ 125°C unless otherwise specified.
Symbol
Parameter
Condition
Min.
VDD Section
VDD-ON
VDD-OFF
IDD-OP
IDD-ST
VDD-OVP
Turn-On Threshold Voltage
Turn-Off Threshold Voltage
Operating Current
Startup Current
VDD Over-Voltage-Protection
VBIAS-VDD-OFF BIAS Clamp Voltage at VDD-OFF
VBIAS-VDD-ON BIAS Clamp Voltage at VDD-ON
Gate Section
CLOAD=1 nF
VDD=6 V
VIN(3)=30 V,
RBIAS=20 k
VIN(3)=30 V,
RBIAS=20 k
9.1
6.75
4
-
25
21.3
17.6
VOL Output Voltage Low
VOH Output Voltage High
Isource
Isink
Peak Sourcing Current(4)
Peak Sinking Current(4)
tr Rising Time
tf Falling Time
VGATE-CLAMP GATE Clamp Voltage
Oscillator Section
IGATE=-1 mA
IGATE=+1 mA,
VDD=10 V
CLOAD=1 nF
CLOAD=1 nF
VDD=20 V
5
100
20
12
fD Operating Frequency at D.Mode
TJ=25°C
65
fND-MAX Max. Frequency at ND.Mode
TJ=25°C
65
fND-MIN Min. Frequency at ND.Mode
TJ=25°C
26
tON-MAX
tON-MIN
Maximum Turn-On Time
Minimum Turn-On Time(4)
TJ=25°C
VFB=0 V
10.4
Current Sense Section
tLEB Leading-Edge Blanking Time(4)
tPD
VCS/IVS
Propagation Delay to GATE
Line Compensation Ratio(4)
50
Voltage Sense Section
tDIS-BNK
tDIS Blanking Time at VS Sampling(4)
IVS-BNK VS Current for VS Blanking
67
VVS-CLAMP VS Clamping Voltage
IVS=1 mA
IVS=10 µA
-0.1
Notes:
3. VIN is external voltage source and RBIAS is connected between VIN and BIAS pin.
4. This parameter, although design-guaranteed, is not tested in production.
Typ.
10.6
7.75
5
2
27
24.4
19.5
60
180
150
60
15
70
70
29.5
12.4
600
300
100
21.5
1.5
80
Max. Unit
12.1
8.75
6
10
29
27.5
21.4
V
V
mA
μA
V
V
V
1.5 V
V
mA
mA
200 ns
100 ns
18 V
75
75
33
14.4
kHz
kHz
kHz
s
ns
150
93
0.35
ns
ns
V/A
μs
μA
V
V
© 2014 Fairchild Semiconductor Corporation
FL7734 • Rev. 1.0
5
www.fairchildsemi.com

5 Page





FL7734MX arduino
Short-LED Protection
In a short-LED condition, the switching MOSFET and
secondary diode are usually stressed by the high
powering current.
GATE Turn-off
VCS-HIGH-CL (1.2 V)
LEB
VCS-LOW-CL (0.2 V)
CS
VVS-LOW-CL-H (0.5 V) /
VVS-LOW-CL-L (0.4 V)
S/H
VS
Short-LED
Protection
Debounce
Count
VVS-SLP-TH (0.4 V)
Figure 21. Short LED Protection
FL7734 changes the current-limit level in a short-LED
condition. When sampled VS voltage is lower than VVS-
LOW-CL-L (0.4 V), the current-limit level is reduced to 0.2 V
from 1.2 V, as shown in Figure 21 so that powering is
limited and external componentscurrent stress is
relieved. When the sampled VS voltage is continuously
lower than VVS-SLP-TH (0.4 V) for 3 consecutive switching
cycles, short-LED protection is triggered with gate
shutdown. After all types of protection including short-
LED protection is triggered, FL7734 internally counts 4
seconds for auto restart and begins startup sequence
again.
Open-LED Protection
When output load is open as high impedance, the
output capacitor should be protected by limiting the
capacitor voltage less than its maximum rating. FL7734
can detect the output over-voltage condition by sensing
both VDD and VS voltages. When VDD voltage is
higher than VDD-OVP (27 V typical) or sampled VS voltage
is higher than VVS-OVP (3 V typical), protection is
triggered. The protection mode is auto restart so normal
operation resumes when the fault condition is removed.
Sensing Resistor Short Protection
During SS3, the controller operates in current-mode
control and the peak CS voltage is 0.2 V during
switching mode. When a sensing resistor is short
circuited, CS voltage cannot reach 0.2 V and turn on
time is maximized with potential damage of switching
MOSFET. In order to provide protection against the
failure, FL7734 compares CS voltage with VCS-SRSP
(0.1 V) during the initial two switching operation. When
VCS doesn’t reach 0.1 V for the two switching, Sensing
Resistor Short Protection (SRSP) is triggered. In normal
condition, input voltage corresponding to 1.5 V VVIN is
high enough to make VCS higher than 0.1 V with turn-on
time shorter than maximum turn-on time.
VVIN
SS2
SS3
1.5 V
VGATE
VCS
0.1 V
Max. tON
SRSP
Time
Figure 22. Sensing Resistor Short Protection
Under-Voltage Lockout (UVLO)
The turn-on and turn-off thresholds are fixed internally at
10.6 V and 7.75 V, respectively. During startup, the
VDD capacitor must be charged higher than 10.6 V
through the external bleeding MOSFET. The bleeding
MOSFET supplies VDD operating current until power
can be delivered from the auxiliary winding of the main
transformer. Generally at small phase angle range, VDD
supply time from auxiliary winding is short and VDD could
reach to VDD-OFF (7.75 V). If VDD drops below VDD-OFF,
VDD hiccup occurs with a certain hiccup frequency
determined by VDD capacitor value and VDD supply
current from auxiliary winding. This hiccup mode could
cause LED flicker. In order to remove the unstable
mode of operation, external bleeding circuit never allows
VDD voltage to fall down less than VDD-OFF (7.75 V) once
input power is supplied.
Over-Temperature Protection (OTP)
The built-in temperature-sensing circuit shuts down
PWM output if the junction temperature exceeds 150°C.
After Over-Temperature Protection (OTP) is triggered,
FL7734 repeats auto-restart time counting until the
junction temperature is lowered less than 140°C.
Different from Short/Open-LED protection and SRSP,
startup sequence doesnt appear every 4 seconds of
auto-restart delay time because the temperature is
detected by monitoring internally, not by checking
external pin information. Normal startup sequence is
started again when the junction temperature is out of the
hysteresis temperature (140°C).
© 2014 Fairchild Semiconductor Corporation
FL7734 • Rev. 1.0
11
www.fairchildsemi.com

11 Page







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