Fairchild FAN5340 Synchronous constant-current series boost led driver with pwm brightness control and integrated load disconnect Datasheet

FAN5340
Synchronous Constant-Current Series Boost LED Driver
with PWM Brightness Control and Integrated Load
Disconnect
Features
Description
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The FAN5340 is a synchronous constant-current LED driver
capable of efficiently delivering up to 500mW to a string of up
to four LEDs in series. Optimized for small form-factor
applications, the 1.2MHz fixed switching frequency allows
the use of chip inductors and capacitors.
Synchronous Current-Mode Boost Converter
Up to 500mW Output Power
Supports 2, 3, or 4 LEDs in Series
2.7V to 4.8V Input Voltage Range
1.2MHz Fixed Switching Frequency
1mA Maximum Quiescent Current
Soft-Start Capability
Input Under-Voltage Lockout (UVLO)
Output Over-Voltage Protection (OVP)
Short-Circuit Detection
Thermal Shutdown (TSD) Protection
For safety, the device features integrated short-circuit
detection plus over-voltage and thermal shutdown
protections. In addition, input under-voltage lockout
protection is triggered if the battery voltage is low.
Brightness (dimming) control is implemented by applying a
PWM signal of 300Hz to 1kHz on the EN pin. During
shutdown, the FAN5340 disconnects the LED anodes from
the output of the boost regulator, which holds the boost
regulator’s voltage on COUT, reducing audible noise from the
PWM dimming and removing power from the LED string.
8-Lead 3.00 x 3.00mm MLP
8-Bump 1.57 x 1.57mm WLCSP
GND
Applications
ƒ Cellular Phones, Smart Phones
ƒ Pocket PCs
ƒ WLAN DC-DC Converter Modules
ƒ PDA, DSC, PMP, and MP3 Players
EN
VLED
FB
8
2
7
3
P1
GND
6
4
5
VIN
VOUT COUT
CIN
L1
2–4
LEDs
1
SW
PGND
RSET
Figure 1.
Typical Application
Ordering Information
Part Number
Operating
Temperature Range
FAN5340UCX
-40 to 85°C
8-Bump, 1.57 x 1.57mm Wafer Level Chip-Scale
Package (WLCSP)
Tape and Reel
FAN5340MPX
(Prelminary)
-40 to 85°C
8-Lead, 3.00 x 3.00mm Molded Leadless
Package (MLP)
Tape and Reel
© 2010 Fairchild Semiconductor Corporation
FAN5340 • Rev. 1.0.1
Package
Packing
www.fairchildsemi.com
FAN5340 — Synchronous Constant-Current Boost Series LED Driver with PWM Brightness Control
April 2010
L1
SW
VIN
Q1
Q2
D1
CIN
GATE
DRIVE
VOUT
PGND
COUT
Q3
VLED
BOOST
CONTROL
2–4
LEDs
EN
GND
FB
RSET
Figure 2.
Table 1.
15 133Ω
Block Diagram
Recommended External Components
Component
Description
Vendor
Parameter
(1)
Min.
Typ.
Max.
Units
22
μH
4.7μF X5R or Better
DCR (Series R)
C
1100
4.7
mΩ
μF
4.7μF X5R or Better
C
4.7
μF
L1
22μH Nominal
COUT
CIN
Murata
LQH3NPN220MGOK
L
Note:
1. Minimum L (inductance) incorporates tolerance, temperature, and DC bias effects (L decreases with increasing current).
© 2010 Fairchild Semiconductor Corporation
FAN5340 • Rev. 1.0.1
www.fairchildsemi.com
2
FAN5340 — Synchronous Constant-Current Boost Series LED Driver with PWM Brightness Control
Block Diagrams
GND
EN
VLED
A1
A2
A3
A3
VIN
B1
B3
A2
FB
B3
C1
C2
C3
VOUT
SW
PGND
C3
Figure 3.
A1
WLCSP Package, Top View
GND
1
EN
2
VLED
3
FB
4
Figure 5.
Figure 4.
P1
GND
8
VIN
7
VOUT
6
SW
5
PGND
B1
C2
C1
WLCSP Package, Bottom View
8-Pin 3 x 3mm MLP, Top View
Pin Definitions
Pin #
Name
Description
CSP
MLP
A1
1
GND
A2
2
EN
A3
3
VLED
B3
4
FB
C3
5
PGND
C2
6
SW
Switching Node. Tie inductor L1 from VIN to this pin.
C1
7
VOUT
Boost Output Voltage. Output of the boost regulator.
B1
8
VIN
© 2010 Fairchild Semiconductor Corporation
FAN5340 • Rev. 1.0.1
Analog Ground. All signals are referenced to this pin.
Enable / PWM Brightness Control. A logic LOW on this pin shuts down the IC,
disconnects the LEDs from VOUT, and reduces the current consumption of the IC. This
terminal has an internal pull-down resistor of 300kΩ.
LED String Output. Connected to the anode of a series string of two to four LEDs.
Current Feedback. The boost regulator regulates this pin to 0.5V to control the LED string
current. Tie this pin via a current-setting resistor (RSET) to GND and the cathode of the LED
string.
Power Ground. The boost switch and gate drivers are grounded at this pin.
Input Voltage.
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FAN5340 — Synchronous Constant-Current Boost Series LED Driver with PWM Brightness Control
Pin Configuration
Stresses exceeding the absolute maximum ratings may damage the device. The device may not function or be operable
above the recommended operating conditions and stressing the parts to these levels is not recommended. In addition,
extended exposure to stresses above the recommended operating conditions may affect device reliability. The absolute
maximum ratings are stress ratings only.
Symbol
Min.
Max.
Units
VIN
–0.3
6.0
V
FB, EN Pins
–0.3
VIN + 0.3
V
VSW
SW Pin
–0.3
24.0
V
VOUT
VOUT Pin
24.0
V
VIN
VFB, VEN
ESD
Parameter
–0.3
Electrostatic Discharge
Protection Level
Human Body Model per JESD22-A114
4.0
Charged Device Model per JESD22-C101
1.5
kV
TJ
Junction Temperature
–40
+150
°C
TSTG
Storage Temperature
–65
+150
°C
+260
°C
TL
Lead Soldering Temperature, 10 Seconds
Recommended Operating Conditions
The Recommended Operating Conditions table defines the conditions for actual device operation. Recommended operating
conditions are specified to ensure optimal performance to the datasheet specifications. Fairchild does not recommend
exceeding them or designing to absolute maximum ratings.
Symbol
VIN
Parameter
Min.
Typ.
Max.
Units
V
VIN Supply Voltage
2.7
4.8
VOUT
VOUT Voltage
6.2
16.0
V
IOUT
VOUT Load Current
5
40
mA
1000
Hz
fEN_PWM
EN pin PWM Dimming Frequency
100
300
TA
Ambient Temperature
–40
+85
°C
TJ
Junction Temperature
–40
+125
°C
Thermal Properties
Junction-to-ambient thermal resistance is a function of application and board layout. This data is measured with four-layer
2s2p evaluation boards in accordance to JEDEC standard JESD51. Special attention must be paid not to exceed junction
temperature TJ(max) at a given ambient temperate TA.
Symbol
θJA
Parameter
Junction-to-Ambient Thermal Resistance
© 2010 Fairchild Semiconductor Corporation
FAN5340 • Rev. 1.0.1
Typ.
Units
WLCSP Package
110
°C/W
MLP Package
49
°C/W
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FAN5340 — Synchronous Constant-Current Boost Series LED Driver with PWM Brightness Control
Absolute Maximum Ratings
VIN = 2.7V to 4.8V and TA = -40°C to +85°C unless otherwise noted. Typical values are at TA = 25°C and VIN = 3.6V.
Symbol
Parameter
Conditions
Min.
Typ.
Max.
Units
1
mA
0.3
1.0
μA
Power Supplies
IQ
Quiescent Current
EN = VIN, Device Not Switching
ISD
Shutdown Supply Current
EN = GND, VIN = 3.6V
VUVLO
VUVHYST
Under-Voltage Lockout
VIN Rising
2.30
2.40
2.50
V
VIN Falling
2.00
2.15
2.25
V
Under-Voltage Lockout Hysteresis
250
mV
EN: Enable Pin
VIH
HIGH-Level Input Voltage
1.2
VIL
LOW-Level Input Voltage
REN
EN Pull-Down Resistance
tSD
EN Low to Shutdown Delay
V
0.4
V
400
kΩ
80
ms
500
520
mV
VFB = 500mV
0.1
1.0
μA
VIN = 3.6V, VOUT = 10V, ISW = 100mA
600
VIN = 2.7V, VOUT = 10V, ISW = 100mA
850
RDS(ON)_Q2 Synchronous Rectifier On-Resistance
VOUT = 10V, ISW = 100mA
2.0
Ω
RDS(ON)_Q3 Load Switch On-Resistance
VOUT = 10V, ILED = 10mA
2.8
Ω
SW Node Leakage
EN = 0, VIN = VSW = VOUT = 5.5V,
VLED = 0
0.1
1.0
μA
Boost Switch Peak Current Limit
VIN = 3.6V
325
400
475
mA
1.0
1.2
1.4
MHz
100
%
20.0
V
200
From Falling Edge of EN
300
20
Feedback and Reference
VFB
Feedback Voltage
480
IFB
Feedback Input Current
Power Outputs
RDS(ON)_Q1 Boost Switch On-Resistance
ISW(OFF)
ILIM-PK
(2)
mΩ
Oscillator
fSW
Boost Regulator Switching Frequency
PWM Dimming
DPWM
(3)
PWM Duty Cycle
PWM Dimming Frequency ≤1kHz
1.0
Output and Protection
VOVP
VOVPHYST
VTHSC
DMAX
Boost Output Over-Voltage Protection
18.0
OVP Hysteresis
VLED Short-Circuit Detection Threshold
Maximum Boost Duty Cycle
19.0
0.8
V
VOUT Falling
VIN – 1.5
V
VOUT Rising
VIN – 1.3
V
(3)
85
%
(3)
DMIN
Minimum Boost Duty Cycle
TSD
Thermal Shutdown
150
20
°C
%
THYS
Thermal Shutdown Hysteresis
25
°C
Notes:
2. SW leakage current includes the leakage current of three internal switches; SW to GND, VOUT to VLED, and SW to VOUT.
3. Guaranteed by design.
© 2010 Fairchild Semiconductor Corporation
FAN5340 • Rev. 1.0.1
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FAN5340 — Synchronous Constant-Current Boost Series LED Driver with PWM Brightness Control
Electrical Specifications
VIN = 3.6V, TA = 25°C, ILED = 20mA, L = 22µH, COUT = 4.7µF.
Figure 6.
Efficiency vs. LED Current: Two LEDs
Figure 8.
Efficiency vs. LED Current: Four LEDs
Figure 10.
Figure 7.
FB Voltage vs. Input Voltage
vs. Temperature
© 2010 Fairchild Semiconductor Corporation
FAN5340 • Rev. 1.0.1
Efficiency vs. LED Current: Three LEDs
Figure 9.
fSW vs. Input Voltage vs.Temperature
Figure 11.
OVP vs. Input Voltage vs. Temperature
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FAN5340 — Synchronous Constant-Current Boost Series LED Driver with PWM Brightness Control
Typical Characteristics
Figure 12.
PWM Linearity Over Full Dimming Duty
Cycle Range, Four LEDs
Figure 14.
Figure 16.
Figure 13.
Figure 15.
Maximum Output Current at VOUT
PWM Linearity with Dimming Duty Cycle
<2.5%, Four LEDs
Line Transient with 10µs Line Step,
Four LEDs
Over-Voltage Protection: Soft-Start into
Open LED String
© 2010 Fairchild Semiconductor Corporation
FAN5340 • Rev. 1.0.1
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FAN5340 — Synchronous Constant-Current Boost Series LED Driver with PWM Brightness Control
Typical Characteristics (Continued)
Figure 17.
Cold-Start Waveform with 100% Duty
Cycle at 1ms/Div.
Figure 18. Cold-Start Waveform with 100% Duty
Cycle Showing Startup, Shutdown and
Startup at 10ms/Div
Figure 19. FAN5340 ILOAD Step from 20mA to 30mA
by Enabling FAN5640 at 10mA, Three LEDs
© 2010 Fairchild Semiconductor Corporation
FAN5340 • Rev. 1.0.1
Figure 20. FAN5340 ILOAD Step from 30mA to 20mA
by Disabling FAN5640 at 10mA, Three LEDs
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FAN5340 — Synchronous Constant-Current Boost Series LED Driver with PWM Brightness Control
Typical Characteristics (Continued)
Overview
Over-Voltage Protection
The FAN5340 is an inductive current-mode boost serial LED
driver that achieves LED current regulation by maintaining
0.5V across RSET. The current through the LED string (ILED)
is therefore:
If the LED string is open circuit, FB remains at 0V and the
output voltage continues to increase in the absence of an
Over-Voltage Protection (OVP) circuit. The FAN5340’s OVP
circuit disables the boost regulator when VOUT exceeds
19.0V and continues to keep the regulator off until VOUT
drops below 18.2V.
I LED =
0 .5
RSET
(1)
Thermal Shutdown
While the forward-voltage across the LEDs determines VOUT,
the FAN5340’s boost regulator output can also support
additional loads on VOUT (see Figure 21) provided its input
current limit is not exceeded.
If the die temperature exceeds 150°C, a reset occurs and
remains in effect until the die cools to 125°C, at which time
the circuit is allowed to begin the soft-start sequence.
Applications
Using VOUT to Drive Additional LED Strings
The VOUT pin can be used as a supply for simple current
sources (shown in Figure 22 using the FAN5640) or discrete
current sinks. To avoid dragging VOUT down when the EN pin
is LOW, the auxiliary strings should not be enabled unless
the EN pin is HIGH. The auxiliary strings can therefore be
PWM dimmed using either the same line as the EN line as
shown below or enabled separately, but within the on-time of
the FAN5340.
IOUT1
1
GND
R1
Figure 21.
2
RSET
GND
If EN has been LOW for more than 20ms, the IC initiates a “cold
start” soft-start cycle when EN rises, provided VIN is above the
UVLO threshold. The soft-start circuit ramps the voltage
reference to the error amplifier to control inrush current.
VLED
FB
5
4
1
8
2
7
3
4
FAN5340
6
5
IOUT2
VIN
EN
VIN
VOUT
COUT
CIN
L1
EN
FAN5640
3
Maximum Output Current
vs. Input Voltage
UVLO and Soft-Start
6
SW
PGND
R2
PWM Dimming
When EN goes LOW, the IC turns off a MOSFET (Q3 in
Figure 2), which disconnects the LED load, preventing COUT
from being discharged when EN is LOW. As long as EN is
low for less than 20ms, the regulator’s main regulation loop
quickly regains control when EN returns to a HIGH state.
Figure 22.
Driving Additional LED Strings
If using VOUT to drive additional loads, care should be taken
not to exceed the input current limit. This limitation is shown in
Figure 21 for a typical IC. The total load (IOUT1 + IOUT2 + ILED)
should always remain below 70% of the value in Figure 21.
Short-Circuit Detection
If VOUT falls below VIN – 1.5V, Q3 turns off and remains off
until VOUT recovers to at least VIN – 1.3V.
© 2010 Fairchild Semiconductor Corporation
FAN5340 • Rev. 1.0.1
www.fairchildsemi.com
9
FAN5340 — Synchronous Constant-Current Boost Series LED Driver with PWM Brightness Control
Circuit Description
Product-Specific Dimensions
Product
D
E
X
Y
FAN5340UC
1.570
1.570
0.285
0.285
Figure 23.
8-Bump, 1.57 x 1.57mm Wafer Level Chip-Scale Package (WLCSP)
Package drawings are provided as a service to customers considering Fairchild components. Drawings may change in any manner without
notice. Please note the revision and/or date on the drawing and contact a Fairchild Semiconductor representative to verify or obtain the most
recent revision. Package specifications do not expand the terms of Fairchild’s worldwide terms and conditions, specifically the warranty therein, which
covers Fairchild products.
Always visit Fairchild Semiconductor’s online packaging area for the most recent package drawings:
http://www.fairchildsemi.com/packaging/.
© 2010 Fairchild Semiconductor Corporation
FAN5340 • Rev. 1.0.1
www.fairchildsemi.com
10
FAN5340 — Synchronous Constant-Current Boost Series LED Driver with PWM Brightness Control
Physical Dimensions
FAN5340 — Synchronous Constant-Current Boost Series LED Driver with PWM Brightness Control
Physical Dimensions (Continued)
Figure 24.
8-Pin, 3 x 3mm Molded Leadless Package (MLP)
Package drawings are provided as a service to customers considering Fairchild components. Drawings may change in any manner without
notice. Please note the revision and/or date on the drawing and contact a Fairchild Semiconductor representative to verify or obtain the most
recent revision. Package specifications do not expand the terms of Fairchild’s worldwide terms and conditions, specifically the warranty therein, which
covers Fairchild products.
Always visit Fairchild Semiconductor’s online packaging area for the most recent package drawings:
http://www.fairchildsemi.com/packaging/.
© 2010 Fairchild Semiconductor Corporation
FAN5340 • Rev. 1.0.1
www.fairchildsemi.com
11
FAN5340 — Synchronous Constant-Current Boost Series LED Driver with PWM Brightness Control
12
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© 2010 Fairchild Semiconductor Corporation
FAN5340 • Rev. 1.0.1
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