SGM3732
PWM Dimming, 38V Step-Up LED Driver
GENERAL DESCRIPTION
FEATURES
The SGM3732 is a versatile constant current LED
● Wide Output Range: Up to 10 Series LEDs
driver
● Integrated 40V High Current Switch (1.35A Limit)
with
architecture.
a
high
The
efficiency step-up
low-side
power
converter
MOSFET
is
● 2.7V to 5.5V Input Voltage Range
integrated in the device, significantly shrinking the
● High Efficiency PWM Converter
overall PCB layout area and minimizing the total
● Low 200mV Feedback Voltage
number of external components. Unique technology
● 500kΩ Pull-Down Resistor on CTRL Pin
and high 1.35A current limit allow SGM3732 to drive up
● 2kHz to 60kHz PWM Dimming Frequency
to 38V output (10 LEDs in series). Alternatively,
● 38V Open LED Protection
SGM3732 can deliver 260mA total current with 3 series
● 1.1MHz Switching Frequency
LEDs per string. It can also maximize the current
● Integrated Soft-Start Function
capability while achieving high conversion efficiency.
● Less than 1µA Shutdown Current
The optimized 1.1MHz switching frequency results in
● Simple, Small Solution Size
reduced conduction loss and small external component
● Available in a Green TSOT-23-6 Package
size. Digital PWM dimming interface is integrated to
● -40℃ to +85℃ Operating Temperature Range
adjust LED current. The PWM frequency is in the range
from 2kHz to 60kHz.
APPLICATIONS
Various protection features are built into the SGM3732,
including cycle-by-cycle input current limit protection,
LED Backlighting
open LED (output over-voltage) protection and thermal
Mobile Phones
shutdown protection. The leakage current in shutdown
Handheld Devices
mode is less than 1µA.
Digital Photo Frames
The SGM3732 is available in a Green TSOT-23-6
Automotive Navigation
package. It operates over an ambient temperature
range of -40℃ to +85℃.
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SEPTEMBER 2021 – REV. A. 4
SGM3732
PWM Dimming, 38V Step-Up LED Driver
PACKAGE/ORDERING INFORMATION
MODEL
PACKAGE
DESCRIPTION
SPECIFIED
TEMPERATURE
RANGE
ORDERING
NUMBER
PACKAGE
MARKING
PACKING
OPTION
SGM3732
TSOT-23-6
-40℃ to +85℃
SGM3732YTN6G/TR
SKAXX
Tape and Reel, 3000
MARKING INFORMATION
NOTE: XX = Date Code.
YYY X X
Date Code - Month
Date Code - Year
Serial Number
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.
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
TSOT-23-6, θJA ........................................................ 120℃/W
Junction Temperature .................................................+150℃
Storage Temperature Range ........................ -65℃ to +150℃
Lead Temperature (Soldering, 10s) ............................+260℃
ESD Susceptibility
HBM ............................................................................. 4000V
MM ................................................................................. 200V
Stresses beyond those listed in Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to
absolute maximum rating conditions for extended periods
may affect reliability. Functional operation of the device at any
conditions beyond those indicated in the Recommended
Operating Conditions section is not implied.
RECOMMENDED OPERATING CONDITIONS
Input Voltage Range ...........................................2.7V to 5.5V
Operating Temperature Range ....................... -40℃ to +85℃
ESD SENSITIVITY CAUTION
This integrated circuit can be damaged if ESD protections are
not considered carefully. 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 even small parametric changes could cause the
device not to meet the published specifications.
DISCLAIMER
SG Micro Corp reserves the right to make any change in
circuit design, or specifications without prior notice.
SG Micro Corp
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SEPTEMBER 2021
2
SGM3732
PWM Dimming, 38V Step-Up LED Driver
PIN CONFIGURATION
(TOP VIEW)
SW
1
6
VIN
GND
2
5
VOUT
FB
3
4
CTRL
TSOT-23-6
PIN DESCRIPTION
PIN
NAME
FUNCTION
1
SW
2
GND
3
FB
4
CTRL
Control Pin of the Boost Regulator. It is a multi-functional pin which can be used
for enable control and digital PWM dimming.
5
VOUT
Output and Over-Voltage Protection Pin.
6
VIN
Converter Switching Node.
Ground.
Output Feedback Pin Regulated at 200mV.
IC Supply. Connect VIN to a supply voltage between 2.7V and 5.5V.
TYPICAL APPLICATION
Up to 38V Output
Input Range
2.7V ~ 5.5V
L
CIN
D1
6
1
VIN
SW
VOUT
4
PWM Dimming
SGM3732
CTRL
FB
COUT
5
White LEDs
Up to 10 in series
Or up to 10S4P
3
1kΩ
GND
RSET
2
Figure 1. Typical Application Circuit
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SEPTEMBER 2021
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SGM3732
PWM Dimming, 38V Step-Up LED Driver
ELECTRICAL CHARACTERISTICS (1)
(VIN = 3.6V, L = 10μH, CIN = 10μF, COUT = 0.47μF, Full = -40℃ to +85℃, typical values are at TA = +25℃, unless otherwise
noted.)
PARAMETER
SYMBOL
CONDITIONS
TEMP
MIN
Full
2.7
TYP
MAX
UNITS
5.5
V
2.6
V
IC Supply
Input Voltage Range
Input Under-Voltage Lockout
UVLO Hysteresis
Quiescent Current (Non Switching)
Operating Current (Switching)
VIN Pin Shutdown Current
VIN
UVLO
Rising edge
VHYS
IQ
ISHDN
+25℃
2.5
+25℃
0.15
V
VFB = 0.4V
+25℃
0.20
0.35
mA
VFB = 0V
+25℃
0.72
1.5
mA
VEN = 0V
+25℃
0.1
1
μA
Step-Up Converter
Voltage Feedback Regulation Voltage
Voltage Feedback Regulation Voltage Under
Brightness Control
VREF Filter 3dB Frequency
VREF
VREF_PWM
fPWM = 10kHz, duty cycle = 3%
Full
192
200
212.5
mV
+25℃
3.5
6
8.5
mV
fREF(3dB)
+25℃
600
Voltage Feedback Input Bias Current
IFB
Full
0.001
0.3
μA
SW Pin Leakage Current
ISW
+25℃
0.01
1
μA
Peak NMOS Current Limit
ILIM
+25℃
fS
Full
0.90
1.10
1.4
MHz
Full
35.5
38.0
40.5
V
Oscillator Frequency
Over-Voltage Threshold
Start-Up Time
VOVP
Measured at VOUT pin
tS
+25℃
Logic Low Threshold
VIL
Full
Logic High Threshold
VIH
Full
Hz
1.35
A
μs
800
Control
0.35
1.5
PWM Dimming Frequency Range
DFR
+25℃
2
Minimum Shutdown Pulse Width Timing
tOFF
+25℃
3
V
V
60
kHz
ms
Junction Thermal Shutdown Threshold
150
℃
Junction Thermal Shutdown Hysteresis
15
℃
NOTE:
1. The SGM3732 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
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SEPTEMBER 2021
4
SGM3732
PWM Dimming, 38V Step-Up LED Driver
RECOMMENDED COMPONENTS OF TEST CIRCUITS
Inductor
Component
Component
22μH/CD75NP-220KC
10μF/C2012X7R1H106KT
10μH/CD75NP-100KC
Diode
0.47μF/C2012X7R1H474KT
Capacitor
MBR0540
TYPICAL PERFORMANCE CHARACTERISTICS
TA = +25℃, L = 10μH, CIN = 10μF, COUT = 0.47μF, unless otherwise noted.
Switching Waveform
Open LED Protection
VIN = 3.6V, ILED = 20mA, L=10μH, 8 LEDs
200mA/div
IL
VOUT
500mA/div
200mV/div
AC Coupled
VOUT
200mV/div 10V/div
20V/div
VSW
VFB
IL
VIN = 3.6V, ILED = 20mA, L = 10μH, 8 LEDs
Time (1μs/div)
Time (100μs/div)
Start-Up
Output Ripple at PWM Dimming
10V/div
VOUT
200mA/div
IL
VIN = 3.6V, ILED = 20mA, L = 10μH, 8 LEDs
Time (1ms/div)
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PWM
AC Coupled
VOUT
ILED
VIN = 3.6V, ILED = 20mA, fPWM = 10kHz,
L=10μH, 8 LEDs
2V/div 200mV/div 10mA/div
2V/div
VEN
Time (100μs/div)
SEPTEMBER 2021
5
SGM3732
PWM Dimming, 38V Step-Up LED Driver
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
TA = +25℃, L = 10μH, CIN = 10μF, COUT = 0.47μF, unless otherwise noted.
Feedback Voltage vs. Temperature
Feedback Voltage vs. Input Voltage
215
215
DPWM = 100%
210
Feedback Voltage (mV)
Feedback Voltage (mV)
V IN =3.6V, DPWM = 100%
210
205
200
195
190
185
-50
205
200
195
190
185
-25
0
25
50
75
2.5
100
3
3.5
Efficiency vs. Input Voltage
5
5.5
Efficiency vs. Input Voltage
ILED = 20mA, L = 22μH
ILED = 20mA, L = 10μH
86
Efficiency (%)
86
Efficiency (%)
4.5
90
90
82
78
82
78
74
74
10 LEDs (32V)
10 LEDs (32V)
70
70
2.5
3
3.5
4
4.5
Input Voltage (V)
5
2.5
5.5
Efficiency vs. Output Current
3
3.5
4
4.5
Input Voltage (V)
5
5.5
LED Current vs. PWM Duty Cycle
24
90
V IN = 3.6V, L = 10μH
V IN = 3.6V, ILED = 20mA, L = 10μH, 6 LEDs
21
LED Current (mA)
85
Efficiency (%)
4
Input Voltage (V)
Temperature (℃)
80
75
70
65
18
15
12
f PWM = 2kHz
9
f PWM = 20kHz
6
3
10 LEDs (32V)
0
60
0
5
10
15
20
Output Current (mA)
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25
30
0
20
40
60
PWM Duty Cycle (%)
80
100
SEPTEMBER 2021
6
SGM3732
PWM Dimming, 38V Step-Up LED Driver
FUNCTIONAL BLOCK DIAGRAM
VIN
SGM3732
SW
VIN
Ramp
Generator
Oscillator
LED Current
Control
FB
VOUT
Over-Voltage
Protection
Thermal
Shutdown
Current
Sense
COMP
Gm
VREF
PWM Control
and
Gate Drive
Current
Limit
Voltage
Reference and
PWM
Dimming
Control
Input Logic
and DAC
CTRL
500kΩ
Pull-Down Resistor
Current
Sense
GND
Figure 2. SGM3732 Block Diagram
FUNCTIONAL DESCRIPTION
The SGM3732 uses a constant-frequency currentmode 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 SGM3732 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.
The SGM3732 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
SGM3732 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
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duty cycle mode, ramping up the output 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 SGM3732,
the IC provides typically 200mV 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.
VFB = Duty × 200mV
Where:
Duty = duty cycle of the PWM signal
200mV = 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.
SEPTEMBER 2021
7
SGM3732
PWM Dimming, 38V Step-Up LED Driver
APPLICATION INFORMATION
Inductor Selection
LED Maximum Current Setting
A 6.8μH 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).
LED maximum current setting, IMAX, is determined by
the feedback resistor (RSET in Figure 3). The feedback
voltage is internally set at 200mV when the PWM
dimming duty cycle = 100%. The LED current is
programmed according to the formula IMAX =
200mV/RSET. For accurate LED current settings,
precision 1% resistors are recommended. The formula
and table for RSET selection are shown below.
Capacitor Selection
RSET = 200mV/IMAX
Small size ceramic capacitors are ideal for SGM3732
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.
Table 1. Current Setting Resistor
RSET (Ω)
IMAX Current (mA)
200
1
40.2
5
20.0
10
Diode Selection
13.3
15
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.
10.0
20
6.65
30
2.00
100
L
10μH
Input Power
2.7V ~ 30V
D1
CIN
22μF
COUT
0.47μF
1
SW
6
Bias Voltage
2.7V ~ 5.5V
VOUT
VIN
20mA
10-Series White LEDs
5
SGM3732
C1
0.1μF
PWM
Dimming
4
CTRL
FB
1kΩ
GND
3
RSET
10Ω
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)
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SEPTEMBER 2021
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SGM3732
PWM Dimming, 38V Step-Up LED Driver
APPLICATION INFORMATION (continued)
PCB Layout Considerations
As for all switching power supplies, especially those
high frequency and high current ones, layout is an
important design step. If layout is not carefully done,
the regulator could suffer from instability as well as
noise problems. To reduce switching losses, the SW
pin rise and fall times are made as short as possible. To
prevent radiation of high frequency resonance
problems, proper layout of the high frequency switching
path is essential. Minimize the length and area of all
traces connected to the SW pin and always use a
ground plane under the switching regulator to minimize
inter-plane coupling. The loop including the PWM
switch, Schottky diode, and output capacitor, contains
high current rising and falling in nanosecond and
should be kept as short as possible. Both B1 and B2
(in Figure 4) magnetic Beads are recommended to be
used to reduce EMI.
The input and the output bypass capacitors should be
placed as close to the IC as possible. Minimize trace
lengths between the IC and the inductor, the diode and
the output capacitor; keep these traces short, direct,
and wide. A recommended PCB layout is shown in
Figure 5.
L1
10μH
B1
6
VIN
C1
22μF
C2
NC
CTRL
R1
0R
2
4
R2
100kΩ
SW
VIN
CTRL
VOUT
FB
B2
LED+
BAT54
SGM3732
GND
D1
1
5
3
C3
0.47μF
LEDR3
10R
U1
Figure 4. Schematic
Figure 5. Recommended PCB Layout
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SEPTEMBER 2021
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SGM3732
PWM Dimming, 38V Step-Up LED Driver
REVISION HISTORY
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
SEPTEMBER 2021 ‒ REV.A.3 to REV.A.4
Page
Changed Ordering Information section .....................................................................................................................................................................2
Changed Package Outline Dimensions section ......................................................................................................................................................11
JULY 2016 ‒ REV.A.2 to REV.A.3
Page
Changed Ordering Number .......................................................................................................................................................................................2
Changed Package Outline Dimensions section ......................................................................................................................................................10
JUNE 2015 ‒ REV.A.1 to REV.A.2
Page
New version.............................................................................................................................................................................................................All
JULY 2014 ‒ REV.A to REV.A.1
Page
Added Functional Description section .......................................................................................................................................................................8
Changed Figure 1......................................................................................................................................................................................................9
Changed Figure 2....................................................................................................................................................................................................10
Changes from Original (MARCH 2014) to REV.A
Page
Changed from product preview to production data .................................................................................................................................................All
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10
PACKAGE INFORMATION
PACKAGE OUTLINE DIMENSIONS
TSOT-23-6
0.69
0.95
D
e
E1
2.59
E
0.99
b
RECOMMENDED LAND PATTERN (Unit: mm)
L
A
θ
A1
0.25
c
A2
Symbol
Dimensions In Millimeters
MIN
MOD
MAX
A
-
-
1.100
A1
0.000
-
0.100
A2
0.700
-
1.000
b
0.300
-
0.500
c
0.080
-
0.200
D
2.820
-
3.050
E
1.550
-
1.700
E1
2.650
-
2.950
e
0.950 BSC
L
0.300
-
0.600
θ
0°
-
8°
NOTES:
1. Body dimensions do not include mode flash or protrusion.
2. This drawing is subject to change without notice.
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TX00038.002
PACKAGE INFORMATION
TAPE AND REEL INFORMATION
REEL DIMENSIONS
TAPE DIMENSIONS
P2
W
P0
Q1
Q2
Q1
Q2
Q1
Q2
Q3
Q4
Q3
Q4
Q3
Q4
B0
Reel Diameter
A0
P1
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
Diameter
Reel Width
W1
(mm)
A0
(mm)
B0
(mm)
K0
(mm)
P0
(mm)
P1
(mm)
P2
(mm)
W
(mm)
Pin1
Quadrant
TSOT-23-6
7″
9.5
3.20
3.10
1.10
4.0
4.0
2.0
8.0
Q3
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TX10000.000
DD0001
Package Type
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)
Pizza/Carton
7″ (Option)
368
227
224
8
7″
442
410
224
18
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DD0002
Reel Type
TX20000.000
工商网监
湘ICP备2023018690号
