SGM3720_16 [SGMICRO]
PWM Dimming, 38V Step-Up LED Driver;
| 型号： | SGM3720_16 |
| 厂家： | 
Shengbang Microelectronics Co, Ltd |
| 描述： | PWM Dimming, 38V Step-Up LED Driver |
| 文件： | 总11页 (文件大小：1316K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
SGM3720
PWM Dimming, 38V Step-Up LED Driver
GENERAL DESCRIPTION
FEATURES
The SGM3720 is a versatile constant current LED
driver with high efficiency step-up converter
● Wide Output Range: Up to 10 Series LEDs
● Integrated 40V High Current Switch (1.6A Limit)
● 2.7V to 5.5V Input Voltage Range
● High Efficiency PWM Converter
a
architecture. The low-side power MOSFET is
integrated in the device, significantly shrinking the
overall PCB layout area and minimizing the total
number of external components. Unique technology
and high 1.6A current limit allow SGM3720 to drive up
to 38V output (10 LEDs in series). Alternatively,
SGM3720 can deliver 260mA total current with 3 series
LEDs per string. It can also maximize the current
capability while achieving high conversion efficiency.
The optimized 600kHz switching frequency results in
reduced conduction loss and small external component
size. Digital PWM dimming interface is integrated to
adjust LED current. The PWM frequency is in the range
from 2kHz to 60kHz.
● Low 300mV Feedback Voltage
● 500kΩ Pull-Down Resistor on CTRL Pin
● 2kHz to 60kHz PWM Dimming Frequency
● 38V Open LED Protection
● 600kHz Switching Frequency
● Integrated Soft-Start Function
● Less than 1µA Shutdown Current
● Simple, Small Solution Size
● -40℃ to +85℃ Operating Temperature Range
● Available in Green TSOT-23-6 Package
APPLICATIONS
Various protection features are built into the SGM3720,
including cycle-by-cycle input current limit protection,
open LED (output over-voltage) protection and thermal
shutdown protection. The leakage current in shutdown
mode is less than 1µA.
LED Backlighting
Mobile Phones
Handheld Devices
Digital Photo Frames
Automotive Navigation
The SGM3720 is available in Green TSOT-23-6
package. It operates over an ambient temperature
range of -40℃ to +85℃.
REV. A. 3
SG Micro Corp
www.sg-micro.com
SGM3720
PWM Dimming, 38V Step-Up LED Driver
PACKAGE/ORDERING INFORMATION
SPECIFIED
TEMPERATURE
RANGE
PACKAGE
DESCRIPTION
ORDERING
NUMBER
PACKAGE
MARKING
PACKING
OPTION
MODEL
SGM3720
TSOT-23-6
SGM3720YTN6G/TR-V1
SMFXX
Tape and Reel, 3000
-40℃ to +85℃
NOTE: XX = Date Code.
MARKING INFORMATION
SMF X X
Green (RoHS & HSF): SG Micro Corp defines "Green" to
mean Pb-Free (RoHS compatible) and free of halogen
substances. If you have additional comments or questions,
please contact your SGMICRO representative directly.
Date code - Month ("A" = Jan. "B" = Feb. …"L" = Dec.)
Date code - Year ("A" = 2010, "B" = 2011 …)
Chip I.D.
For example: SMFFA (2015, January)
ABSOLUTE MAXIMUM RATINGS
OVERSTRESS CAUTION
Input Voltage, VIN................................................. -0.3V to 6V
High Voltage Nodes, SW, VOUT ....................... -0.3V to 40V
Other Pins, FB, CTRL...............................-0.3V to VIN + 0.3V
Package Thermal Resistance
Stresses beyond those listed may cause permanent damage
to the device. Functional operation of the device at these or
any other conditions beyond those indicated in the
operational section of the specification is not implied.
Exposure to absolute maximum rating conditions for
extended periods may affect reliability.
TSOT-23-6, θJA ........................................................ 120℃/W
Junction Temperature.................................................+150℃
Storage Temperature Range ........................-65℃ to +150℃
Lead Temperature (Soldering, 10sec) ........................+260℃
ESD SENSITIVITY CAUTION
This integrated circuit can be damaged by ESD if you don’t
pay attention to ESD protection. SGMICRO recommends that
all integrated circuits be handled with appropriate precautions.
Failure to observe proper handling and installation
procedures can cause damage. ESD damage can range from
subtle performance degradation to complete device failure.
Precision integrated circuits may be more susceptible to
damage because very small parametric changes could cause
the device not to meet its published specifications.
ESD Susceptibility
HBM.............................................................................4000V
MM.................................................................................200V
RECOMMENDED OPERATING CONDITIONS
Input Voltage Range...........................................2.7V to 5.5V
Operating Temperature Range.......................-40℃ to +85℃
DISCLAIMER
SG Micro Corp reserves the right to make any change in
circuit design, specification or other related things if
necessary without notice at any time.
SG Micro Corp
www.sg-micro.com
2
SGM3720
PWM Dimming, 38V Step-Up LED Driver
PIN CONFIGURATION
(TOP VIEW)
SW
GND
FB
1
2
3
6
5
4
VIN
VOUT
CTRL
TSOT-23-6
PIN DESCRIPTION
PIN
1
NAME
FUNCTION
SW
Converter Switching Node.
2
GND Ground.
3
FB
Output Feedback Pin Regulated at 300mV.
Control Pin of the Boost Regulator. It is a multi-functional pin which can be used for enable
control and digital PWM dimming.
4
CTRL
5
6
VOUT Output and Over-Voltage Protection Pin.
VIN
IC Supply. Connect VIN to a supply voltage between 2.7V and 5.5V.
TYPICAL APPLICATION
Up to 38V Output
White LEDs
Input Range
2.7V~5.5V
L
D1
CIN
COUT
6
1
VIN
SW
Up to 10 in series
Or up to 10S4P
5
VOUT
FB
SGM3720
4
3
PWM Dimming
CTRL
1kΩ
RSET
GND
2
Figure 1. Typical Application Circuit
SG Micro Corp
www.sg-micro.com
3
SGM3720
PWM Dimming, 38V Step-Up LED Driver
ELECTRICAL CHARACTERISTICS (1)
(VIN = 3.6V, L = 22μH, CIN = 10μF, COUT = 0.47μF, Full = -40℃ to +85℃, typical values are at TA = +25℃, unless otherwise noted.)
PARAMETER
IC SUPPLY
SYMBOL
CONDITIONS
TEMP
MIN
TYP
MAX
UNITS
Input Voltage Range
VIN
Full
2.7
5.5
2.6
V
V
Input Under-Voltage Lockout
UVLO Hysteresis
UVLO
VHYS
Rising edge
2.5
0.15
0.20
0.5
+25℃
+25℃
+25℃
+25℃
+25℃
V
Quiescent Current (Non Switching)
Operating Current (Switching)
VFB = 0.4V
0.35
0.9
1
mA
mA
μA
IQ
VFB = 0V
VEN = 0V
VIN Pin Shutdown Current
ISHDN
0.1
STEP-UP CONVERTER
Voltage Feedback Regulation Voltage
VREF
Full
289
6.5
300
9
311
mV
mV
Voltage Feedback Regulation Voltage
Under Brightness Control
VREF_PWM fPWM = 10kHz, duty cycle = 3%
11.5
+25℃
VREF Filter 3dB Frequency
fREF(3dB)
IFB
600
0.001
0.01
Hz
μA
μA
+25℃
Full
Voltage Feedback Input Bias Current
SW Pin Leakage Current
0.3
1
ISW
+25℃
Peak NMOS Current Limit
Oscillator Frequency
Over-Voltage Threshold
Start-Up Time
ILIM
1.6
600
38.0
800
A
kHz
V
+25℃
Full
fS
480
750
VOVP
tS
Measured at VOUT pin
Full
35.5
40.5
μs
+25℃
CONTROL
Logic Low Threshold
Logic High Threshold
PWM Dimming Frequency Range
VIL
VIH
Full
Full
0.35
60
V
V
1.5
2
DFR
kHz
+25℃
Minimum Shutdown Pulse Width Timing
Junction Thermal Shutdown Threshold
Junction Thermal Shutdown Hysteresis
tOFF
3
ms
℃
+25℃
150
15
℃
NOTE:
1. The SGM3720 is guaranteed to meet performance specifications over the -40℃ to +85℃ operating temperature range by
design, characterization and correlation with statistical process controls.
SG Micro Corp
www.sg-micro.com
4
SGM3720
PWM Dimming, 38V Step-Up LED Driver
RECOMMENDED COMPONENTS OF TEST CIRCUITS
COMPONENT
COMPONENT
INDUCTOR 22μH/CD75NP-220KC
10μF/C2012X7R1H106KT
0.47μF/C2012X7R1H474KT
CAPACITOR
DIODE
MBR0540
TYPICAL PERFORMANCE CHARACTERISTICS
TA = +25℃, L = 22μH, CIN = 10μF, COUT = 0.47μF, unless otherwise noted.
Switching Waveform
Open LED Protection
VFB
VSW
AC Coupled
VOUT
VOUT
IL
IL
VIN = 3.6V, ILED = 20mA, L = 22μH, 8 LEDs
Time (100μs/div)
VIN = 3.6V, ILED = 20mA, L = 22μH, 8 LEDs
Time (1μs/div)
Start-Up
Output Ripple at PWM Dimming
VEN
PWM
VOUT
ILED
AC Coupled
VOUT
IL
VIN = 3.6V, ILED = 20mA, fPWM = 10kHz,
L = 22μH, 8 LEDs
VIN = 3.6V, ILED = 20mA, L = 22μH, 8 LEDs
Time (1ms/div)
Time (100μs/div)
SG Micro Corp
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5
SGM3720
PWM Dimming, 38V Step-Up LED Driver
TYPICAL PERFORMANCE CHARACTERISTICS
TA = +25℃, L = 22μH, CIN = 10μF, COUT = 0.47μF, unless otherwise noted.
Feedback Voltage vs. Temperature
Efficiency vs. Input Voltage
ILED = 20mA, L = 22μH
90
88
86
84
82
80
315
310
305
300
295
290
285
VIN =3.6V, DPWM = 100%
10 LEDs (32V)
-50
-25
0
25
50
75
100
2.5
3
3.5
4
4.5
5
5.5
Temperature (℃)
Input Voltage (V)
Efficiency vs. Output Current
Oscillator Frequency vs. Input Voltage
90
86
82
78
74
70
750
VIN = 3.6V, L = 22μH
700
650
600
550
500
450
10 LEDs (32V)
0
5
10
15
20
25
30
2.5
3
3.5
4
4.5
5
5.5
Input Voltage (V)
Output Current (mA)
LED Current vs. PWM Duty Cycle
24
21
18
15
12
9
V
IN = 3.6V, ILED = 20mA, L = 22μH, 6 LEDs
fPWM = 2kHz
fPWM = 20kHz
6
3
0
0
20
40
60
80
100
PWM Duty Cycle (%)
SG Micro Corp
www.sg-micro.com
6
SGM3720
PWM Dimming, 38V Step-Up LED Driver
FUNCTIONAL BLOCK DIAGRAM
VIN
VOUT
SW
SGM3720
VIN
Ramp
Oscillator
Over-Voltage
Protection
Thermal
Shutdown
Generator
FB
LED Current
Control
Current
Sense
PWM Control
COMP
and
Gm
Gate Drive
VREF
Current
Limit
Voltage
Reference and
PWM
Dimming
Control
Input Logic
and DAC
Current
Sense
CTRL
500kΩ
Pull-Down Resistor
GND
Figure 2. SGM3720 Block Diagram
FUNCTIONAL DESCRIPTION
The SGM3720 uses a constant-frequency current-
mode boost converter architecture to control the LED
current by regulating the feedback voltage. Please refer
to the FUNCTIONAL BLOCK DIAGRAM above for an
explanation of SGM3720 operation. The beginning of
each cycle turns on the Power MOSFET. A slope
compensation ramp is added to the output of the
current sense amplifier and the result is fed into the
positive input of the comparator (COMP). When this
voltage goes above the output voltage of the error
amplifier (Gm), the Power MOSFET is turned off. The
voltage at the output of the Gm block amplifies the
difference between the reference voltage and the
feedback voltage (FB), so that FB voltage can be
regulated to the reference voltage.
Switching will stop when the output reaches the OVP
threshold. The OVP feature protects the IC from
damaging itself by exceeding the voltage rating on
SW/VOUT pins.
For the brightness dimming control of the SGM3720,
the IC provides typically 300mV feedback voltage when
the CTRL pin is pulled constantly high. However, CTRL
pin allows a PWM signal to reduce this regulation
voltage by changing the PWM duty cycle to achieve
LED brightness dimming control. An internal low pass
filter (600Hz) is used to filter the pulse signal. The
relationship between the duty cycle and FB voltage can
be calculated as following equation.
V
FB = Duty × 300mV
The SGM3720 has built-in soft-start to limit the inrush
current during start-up and to limit the amount of
overshoot on the output. Protection features in the
SGM3720 include over-voltage protection (OVP),
cycle-by-cycle current limit protection and thermal
shutdown. OVP protects in the event where an LED
fails open, which forces the feedback voltage to zero.
This causes the boost converter to operate in maximum
duty cycle mode, ramping up the output voltage.
Where:
Duty = duty cycle of the PWM signal
300mV = internal reference voltage
The PWM frequency is in the range from 2kHz to
60kHz, and the recommended minimum PWM duty
cycle is 3% for no blind dimming.
SG Micro Corp
www.sg-micro.com
7
SGM3720
PWM Dimming, 38V Step-Up LED Driver
APPLICATION INFORMATION
dimming duty cycle = 100%. The LED current is
Inductor Selection
programmed according to the formula IMAX
=
A 10μH to 22μH inductor is recommended for 10/8/6
series LED applications and 10S4P LED applications. If
high efficiency is a critical requirement, a low DCR
inductor should be selected. The inductor’s saturation
current rating should also exceed the peak input
current, especially for high load current application (like
10S4P).
300mV/RSET. For accurate LED current settings,
precision 1% resistors are recommended. The formula
and table for RSET selection are shown below.
R
SET = 300mV/IMAX
Table 1. Current Setting Resistor
Capacitor Selection
RSET (Ω)
IMAX Current (mA)
Small size ceramic capacitors are ideal for SGM3720
application. An input capacitor in the range of 1μF to
22μF and a 0.47μF output capacitor are suggested for
10/8/6 series LED applications. For higher output
current applications like 10S4P, larger value output
capacitors like 2.2μF are recommended to minimize
output ripple.
300
1
5
60.4
30.0
20.0
15.0
10.0
3.00
10
15
20
30
100
Diode Selection
The current rating of the Schottky diode should exceed
the peak current of the boost converter. The voltage
rating should also exceed the target output voltage.
Layout Considerations
PCB layout is very important for high frequency
switching regulators in order to keep the loop stable
and minimize noise. The input capacitor should be very
close to the IC to get the best decoupling. The path of
the inductor and output capacitor should be kept as
short as possible to minimize noise and ringing.
LED Maximum Current Setting
LED maximum current setting, IMAX, is determined by
the feedback resistor (RSET in Figure 3). The feedback
voltage is internally set at 300mV when the PWM
22μH
Input Power
2.7V~30V
L
D1
CIN
COUT
22μF
0.47μF
20mA
1
10-Series White LEDs
SW
6
4
5
3
Bias Voltage
2.7V~5.5V
VIN
VOUT
FB
SGM3720
C1
0.1µF
PWM
Dimming
CTRL
1kΩ
RSET
15Ω
GND
2
Figure 3. Application Circuit for 10 LEDs in Series with 20mA Current (VIN can be tied to input power rail if less than 5.5V)
SG Micro Corp
www.sg-micro.com
8
PACKAGE INFORMATION
PACKAGE OUTLINE DIMENSIONS
TSOT-23-6
0.69
0.95
D
e
2.59
E1
E
0.99
b
RECOMMENDED LAND PATTERN (Unit: mm)
L
A
θ
0.25
A1
c
A2
Dimensions
Dimensions
In Inches
In Millimeters
Symbol
MIN
MAX
MIN
MAX
0.043
0.004
0.039
0.020
0.008
0.116
0.065
0.116
A
A1
A2
b
1.000
0.100
0.900
0.500
0.200
2.950
1.650
2.950
0.000
0.700
0.300
0.080
2.850
1.550
2.650
0.000
0.028
0.012
0.003
0.112
0.061
0.104
c
D
E
E1
e
0.950 BSC
0.037 BSC
L
0.300
0°
0.600
8°
0.012
0°
0.024
8°
θ
TX00038.001
SG Micro Corp
www.sg-micro.com
PACKAGE INFORMATION
TAPE AND REEL INFORMATION
REEL DIMENSIONS
TAPE DIMENSIONS
P2
P0
W
Q2
Q4
Q2
Q4
Q2
Q4
Q1
Q3
Q1
Q3
Q1
Q3
B0
Reel Diameter
P1
A0
K0
Reel Width (W1)
DIRECTION OF FEED
NOTE: The picture is only for reference. Please make the object as the standard.
KEY PARAMETER LIST OF TAPE AND REEL
Reel Width
Reel
Diameter
A0
B0
K0
P0
P1
P2
W
Pin1
Quadrant
Package Type
W1
(mm)
(mm) (mm) (mm) (mm) (mm) (mm) (mm)
TSOT-23-6
7″
9.5
3.2
3.1
1.1
4.0
4.0
2.0
8.0
Q3
TX10000.000
SG Micro Corp
www.sg-micro.com
PACKAGE INFORMATION
CARTON BOX DIMENSIONS
NOTE: The picture is only for reference. Please make the object as the standard.
KEY PARAMETER LIST OF CARTON BOX
Length
(mm)
Width
(mm)
Height
(mm)
Reel Type
Pizza/Carton
7″ (Option)
7″
368
442
227
410
224
224
8
18
TX20000.000
SG Micro Corp
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