SGM3735
38V Step-Up LED Driver
GENERAL DESCRIPTION
The SGM3735 is a versatile constant current LED
driver with a high efficiency step-up converter
architecture. Unique technology and high 1.35A current
limit allow SGM3735 to drive up to 38V output (10
LEDs in series). Alternatively, SGM3735 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
1MHz
switching
frequency
results
in
reduced
conduction loss and small external component size. A
single wire dimming interface is integrated to adjust the
FB voltage in 32 steps, which can overcome audible
noise and inrush current issues in normal PWM
dimming schemes.
Various protection features are built into the SGM3735,
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.
The SGM3735 is available in Green TDFN-2×2-8L
package. It operates over an ambient temperature
range of -40℃ to +85℃.
FEATURES
●
Wide Output Range: Up to 10 Series LEDs
●
Integrated 40V High Current Switch (1.35A Limit)
●
2.7V to 5.5V Input Voltage Range
●
High Efficiency PWM Converter
●
Low 200mV Feedback Voltage
●
500kΩ Pull-Low Resistor on EN/SET Pin
●
Single Wire Dimming Interface
●
38V Open LED Protection
●
1MHz Switching Frequency
●
Integrated Soft-Start Function
●
Less than 1µA Shutdown Current
●
Simple, Small Solution Size
●
Available in Green TDFN-2×2-8L Package
●
-40℃ to +85℃ Temperature Range
APPLICATIONS
LED Backlighting
Mobile Phones
Handheld Devices
Digital Photo Frames
Automotive Navigation
SG Micro Corp
www.sg-micro.com
REV. A. 1
SGM3735
PACKAGE/ORDERING INFORMATION
MODEL
SGM3735
PACKAGE
DESCRIPTION
TDFN-2×2-8L
SPECIFIED
TEMPERATURE
RANGE
-40℃ to +85℃
ORDER NUMBER
SGM3735YTDE8G/TR
38V Step-Up LED Driver
MARKING
INFORMATION
3735
XXXX
PACKAGE
OPTION
Tape and Reel, 3000
NOTE:
XXXX
= Date Code.
ABSOLUTE MAXIMUM RATINGS
Input Voltage, V
IN
……………………......….………….-0.3V to 6V
High Voltage Nodes, SW, VOUT……….…………...-0.3V to 40V
Other Pins, FB, EN/SET……………...………-0.3V to V
IN
+ 0.3V
Package Thermal Resistance
TDFN-2×2-8L,
θ
JA
…………..……...….………..…….…....75℃/W
Storage Temperature Range...….……….……...-65℃ to +150℃
Junction Temperature…………………………………….….150℃
Operating Temperature Range...………………....-40℃ to +85℃
Lead Temperature (Soldering 10 sec)
……………………………………………………………...…. 260℃
ESD Susceptibility
HBM..................................................................................3000V
MM......................................................................................200V
NOTE:
Stresses beyond those listed under “Absolute Maximum
Ratings” may cause permanent damage to the device. These
are stress ratings only, and functional operation of the device at
these or any other conditions beyond those indicated in the
operational sections of the specifications is not implied.
Exposure to absolute maximum rating conditions for extended
periods may affect device reliability.
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.
SGMICRO reserves the right to make any change in circuit
design, specification or other related things if necessary without
notice at any time. Please contact SGMICRO sales office to get
the latest datasheet.
SG Micro Corp
www.sg-micro.com
2
SGM3735
PIN CONFIGURATION
(TOP VIEW)
SGM3735
PGND
VIN
EN/SET
GND
1
2
3
4
8
7
6
5
SW
38V Step-Up LED Driver
VOUT
FB
RSET
TDFN-2×2-8L
GND
PIN DESCRIPTION
PIN
1
2
3
4
5
6
7
8
Exposed
Pad
NAME
PGND
VIN
EN/SET
GND
RSET
FB
VOUT
SW
GND
FUNCTION
Power Ground.
Supply Input.
Enable Control and Single Wire Dimming Interface. Drive to a logic high to enable the
device. Use pulse to dim LED brightness. Keep EN/SET pin in "Low" status for 3ms to shut
down chip.
Ground.
RSET Pin. Connect one resistor from RSET to GND to program the maximum white LED
current.
Feedback Input. Connect this pin to the cathode of the white LED.
Output and Over-Voltage Protection Pin.
Switch Output. Connect this pin to the inductor and the Schottky diode.
Exposed pad should be soldered to PCB board and connected to GND.
TYPICAL APPLICATION
Input Range
2.7V~5.5V
C
IN
2
VIN
Up to 38V Output
L
8
SW
VOUT
7
6
5
R
SET
D1
C
OUT
White LEDs
Up to 10 in series
Or up to 10S4P
SGM3735
1kΩ
Brightness control
3
EN/SET
GND
4
PGND
1
FB
RSET
SG Micro Corp
www.sg-micro.com
3
SGM3735
38V Step-Up LED Driver
ELECTRICAL CHARACTERISTICS
(1)
(V
IN
= 3.6V, L = 10μH, C
IN
= 10μF, C
OUT
= 0.47μF, Full = -40℃ to +85℃, typical values are at T
A
= +25℃, unless otherwise noted.)
PARAMETER
IC SUPPLY
Input Voltage Range
Input Under-Voltage Lockout
UVLO Hysteresis
Quiescent Current (Non Switching)
Operating Current (Switching)
VIN Pin Shutdown Current
STEP-UP CONVERTER
Voltage Feedback Regulation Voltage
NMOS On-Resistance
SW Pin Leakage Current
Peak NMOS Current Limit
Oscillator Frequency
Maximum Duty Cycle
Over-Voltage Threshold
Start-Up Time
CONTROL
Logic Low Threshold
Logic High Threshold
Minimum Logic High Pulse Width Timing
Logic Low Pulse Width Timing
Minimum Shutdown Pulse Width Timing
Junction Thermal Shutdown Threshold
Junction Thermal Shutdown Hysteresis
V
IL
V
IH
t
HIGH_MIN
t
LOW
t
OFF
Full
Full
+25℃
+25℃
+25℃
1.5
0.4
0.4
3
150
15
750
0.35
V
V
μs
μs
ms
℃
℃
V
REF
R
DS(ON)
I
SW
I
LIM
f
S
D
MAX
V
OVP
t
S
Measured at VOUT pin
Full
+25℃
+25℃
+25℃
Full
+25℃
Full
+25℃
1.0
0.8
92
35.5
192
200
0.36
0.01
1.35
1.0
95
38
800
40.5
212.5
0.55
1
1.7
1.22
mV
Ω
μA
A
MHz
%
V
μs
V
IN
UVLO
V
HYS
I
Q
I
SHDN
V
FB
= 0.4V
V
FB
= 0V
V
EN
= 0V
Rising edge
Full
+25℃
+25℃
+25℃
+25℃
+25℃
2.7
2.5
0.15
0.20
0.72
0.1
0.35
1.20
1
5.5
2.6
V
V
V
mA
mA
μA
SYMBOL
CONDITIONS
TEMP
MIN
TYP
MAX
UNITS
NOTE:
1. The SGM3735 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
SGM3735
38V Step-Up LED Driver
TYPICAL PERFORMANCE CHARACTERISTICS
T
A
= +25℃, L = 10μH, C
IN
= 10μF, C
OUT
= 0.47μF, unless otherwise noted.
Feedback Voltage vs. Temperature
215
Feedback Voltage (mV)
Feedback Voltage (mV)
215
Feedback Voltage vs. Input Voltage
210
205
200
195
190
185
-50
V
IN
= 3.6V
210
205
200
195
190
185
-25
0
25
50
Temperature (℃)
75
100
2.5
3
3.5
4
4.5
Input Voltage (V)
5
5.5
Efficiency vs. Input Voltage
90
I
LED
= 20mA, L = 10μH
88
Efficiency (%)
86
84
82
10 LEDs
80
2.5
3
3.5
4
4.5
Input Voltage (V)
5
5.5
80
2.5
3
Efficiency (%)
88
86
84
82
90
Efficiency vs. Input Voltage
I
LED
= 20mA, L = 22μH
10 LEDs
3.5
4
4.5
Input Voltage (V)
5
5.5
Efficiency vs. Output Current
100
V
IN
= 3.6V, L = 10μH
90
Efficiency (%)
V
SW
Switching Waveform
20V/div
80
70
60
10 LEDs
50
0
5
10
15
20
Output Current (mA)
25
30
I
L
V
OUT
200mV/div
AC Coupled
200mA/div
V
IN
= 3.6V, I
LED
= 20mA, L=10μH, 8 LEDs
Time (1μs/div)
SG Micro Corp
www.sg-micro.com
5
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