SGM3725_16 [SGMICRO]
38V Step-Up LED Driver;
| 型号： | SGM3725_16 |
| 厂家： | 
Shengbang Microelectronics Co, Ltd |
| 描述： | 38V Step-Up LED Driver |
| 文件： | 总13页 (文件大小：1414K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
SGM3725
38V Step-Up LED Driver
GENERAL DESCRIPTION
FEATURES
The SGM3725 is a versatile constant current LED
● 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
driver with
a
high efficiency step-up converter
architecture. Unique technology and high 1.35A current
limit allow SGM3725 to drive up to 38V output (10
LEDs in series). Alternatively, SGM3725 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
1.1MHz switching frequency results in reduced
conduction loss and small external component size. A
single wire 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.
● 500kΩ Pull-Down Resistor on CTRL Pin
● Single Wire Dimming Interface
● 38V Open LED Protection
● 1.1MHz Switching Frequency
● Integrated Soft-Start Function
● Less than 1µA Shutdown Current
● Simple, Small Solution Size
● Available in Green TSOT-23-6 Package
● -40℃ to +85℃ Operating Temperature Range
Various protection features are built into the SGM3725,
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.
APPLICATIONS
LED Backlighting
Mobile Phones
Handheld Devices
Digital Photo Frames
Automotive Navigation
The SGM3725 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
SGM3725
38V Step-Up LED Driver
PACKAGE/ORDERING INFORMATION
SPECIFIED
TEMPERATURE
RANGE
PACKAGE
DESCRIPTION
ORDERING
NUMBER
PACKAGE
MARKING
PACKING
OPTION
MODEL
SGM3725
TSOT-23-6
SGM3725YTN6G/TR-V1
SK9XX
Tape and Reel, 3000
-40℃ to +85℃
NOTE: XX = Date Code.
MARKING INFORMATION
SK9 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: SK9FA (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
SGM3725
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 200mV.
Control Pin of the Boost Regulator. Can be used to enable/disable the IC, as well as to
program the output current at 32 levels.
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
Input Range
2.7V~5.5V
L
D1
CIN
White LEDs
COUT
6
1
VIN
SW
Up to 10 in series
Or up to 10S4P
5
VOUT
SGM3725
1kΩ
4
3
CTRL
FB
Brightness control
RSET
GND
2
Figure 1. Typical Application Circuit
SG Micro Corp
www.sg-micro.com
3
SGM3725
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
TYP
MAX UNITS
IC SUPPLY
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
0.72
0.1
+25℃
+25℃
+25℃
+25℃
+25℃
V
Quiescent Current (Non Switching)
Operating Current (Switching)
VFB = 0.4V
0.35
1.5
1
mA
mA
μA
IQ
VFB = 0V
VEN = 0V
VIN Pin Shutdown Current
ISHDN
STEP-UP CONVERTER
Voltage Feedback Regulation Voltage
Voltage Feedback Input Bias Current
SW Pin Leakage Current
VREF
IFB
Full
Full
192
200
0.001
0.01
212.5
0.3
1
mV
μA
μA
ISW
+25℃
Peak NMOS Current Limit
Oscillator Frequency
Over-Voltage Threshold
Start-Up Time
ILIM
fS
VOVP
tS
1.35
1.10
38.0
800
A
MHz
V
+25℃
Full
0.90
35.5
1.4
Measured at VOUT pin
Full
40.5
μs
+25℃
CONTROL
Logic Low Threshold
Logic High Threshold
Minimum Logic High Pulse Width Timing
VIL
VIH
Full
Full
0.35
750
V
V
1.5
0.4
0.4
3
tHIGH_MIN
μs
+25℃
Logic Low Pulse Width Timing
tLOW
tOFF
μs
ms
℃
+25℃
+25℃
Minimum Shutdown Pulse Width Timing
Junction Thermal Shutdown Threshold
Junction Thermal Shutdown Hysteresis
150
15
℃
NOTE:
1. The SGM3725 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
SGM3725
38V Step-Up LED Driver
RECOMMENDED COMPONENTS OF TEST CIRCUITS
COMPONENT
22μH/CD75NP-220KC
10μH/CD75NP-100KC
MBR0540
COMPONENT
10μF/C2012X7R1H106KT
0.47μF/C2012X7R1H474KT
INDUCTOR
DIODE
CAPACITOR
TYPICAL PERFORMANCE CHARACTERISTICS
TA = +25℃, L = 10μH, 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 = 10μH, 8 LEDs
Time (100μs/div)
VIN = 3.6V, ILED = 20mA, L = 10μH, 8 LEDs
Time (1μs/div)
Start-Up
VEN
VOUT
IL
VIN = 3.6V, ILED = 20mA, L = 10μH, 8 LEDs
Time (1ms/div)
SG Micro Corp
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5
SGM3725
38V Step-Up LED Driver
TYPICAL PERFORMANCE CHARACTERISTICS
TA = +25℃, L = 10μH, CIN = 10μF, COUT = 0.47μF, unless otherwise noted.
Feedback Voltage vs. Temperature
Feedback Voltage vs. Input Voltage
215
210
205
200
195
190
185
215
210
205
200
195
190
185
VIN =3.6V, Not Dimmed
Not Dimmed
-50
-25
0
25
50
75
100
2.5
3
3.5
4
4.5
5
5.5
Input Voltage (V)
Temperature (℃)
Efficiency vs. Input Voltage
Efficiency vs. Input Voltage
ILED = 20mA, L = 22μH
90
86
82
78
74
70
90
86
82
78
74
70
ILED = 20mA, L = 10μH
10 LEDs (32V)
10 LEDs (32V)
2.5
3
3.5
4
4.5
5
5.5
2.5
3
3.5
4
4.5
5
5.5
Input Voltage (V)
Input Voltage (V)
Efficiency vs. Output Current
90
85
80
75
70
65
60
V
IN = 3.6V, L = 10μH
10 LEDs (32V)
0
5
10
15
20
25
30
Output Current (mA)
SG Micro Corp
www.sg-micro.com
6
SGM3725
38V Step-Up LED Driver
FUNCTIONAL BLOCK DIAGRAM
VIN
VOUT
SW
SGM3725
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
Dimming
Control
Input Logic
and DAC
Current
Sense
CTRL
500kΩ
Pull-Down Resistor
GND
Figure 2. SGM3725 Block Diagram
SG Micro Corp
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7
SGM3725
38V Step-Up LED Driver
FUNCTIONAL DESCRIPTION
The SGM3725 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 SGM3725 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 single wire control interface accepts a series of
pulses into the CTRL pin to program the reference
voltage. The number of rising edges is detected
internally and decoded as illustrated in Table 1. The
register contains 5-bits, yielding 32 different current
levels. Using the simplest control method, output
current can be toggled on and off between IMAX and
0mA, by pulling the CTRL pin high or low. IMAX is
programmed by the resistor connected between FB
and GND. Please see LED Maximum Current Setting
section in this document to determine the proper
resistor value. The next level of control is achieved by
injecting a series of pulses into the CTRL pin to
program the reference voltage at 32 levels. The
number of rising edges is detected internally and
decoded to the current level as illustrated in Table 1.
The reference voltage levels are evenly spaced among
these 32 steps.
The SGM3725 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
SGM3725 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.
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.
The first rising edge on the CTRL pin takes the current
level to maximum of 100% of IMAX. Then the current will
be changed with each additional qualified pulse. The
current stays unchanged as long as the CTRL pin stays
high.
Table 1. Current Setting
DATA LED Current Ratio DATA LED Current Ratio DATA LED Current Ratio DATA LED Current Ratio
1
2
3
4
5
6
7
8
32/32
31/32
30/32
29/32
28/32
27/32
26/32
25/32
9
24/32
23/32
22/32
21/32
20/32
19/32
18/32
17/32
17
18
19
20
21
22
23
24
16/32
15/32
14/32
13/32
12/32
11/32
10/32
9/32
25
26
27
28
29
30
31
32
8/32
7/32
6/32
5/32
4/32
3/32
2/32
1/32
10
11
12
13
14
15
16
SG Micro Corp
www.sg-micro.com
8
SGM3725
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 DATA = 1.
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.
R
SET = 200mV/IMAX
Capacitor Selection
Small size ceramic capacitors are ideal for SGM3725
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 2. Current Setting Resistor
RSET (Ω)
200
IMAX Current (mA)
1
5
40.2
20.0
13.3
10.0
6.65
2.00
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.
10μH
Input Power
2.7V~30V
L
D1
CIN
COUT
20mA
10-Series White LE5s
22μF
0.47μF
1
SW
6
5
3
Bias Voltage
2.7V~5.5V
VIN
VOUT
SGM3725
1kΩ
C1
0.1µF
4
CTRL
FB
Brightness control
RSET
GND
2
10Ω
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
9
SGM3725
38V Step-Up LED Driver
APPLICATION INFORMATION
Since the data in Table 1 automatically circles around
after 32 pulses, adding 32-8 = 24 pulses changes from
6/32 (DATA 27) to 14/32 (DATA 19). The second way is
to reset the IC by pulling CTRL pin low for 3ms
(guaranteed shutdown), and then inputting the desired
number of pulses.
Current Setting at CTRL Pin
Current control can be as simple as a bi-level signal at
the CTRL pin, resulting in LEDs ON at 100% IMAX or
LED OFF state. However, more sophisticated control
techniques can be achieved by pulsing the CTRL pin.
An example for programming the output current is
shown in Figure 4.
Example: going from 6/32 (DATA 27) to 14/32 (DATA
19)
There are two ways to adjust the channels’ ON/OFF
state or current level. The first way is by simply adding
the number of pulses according to Table 2. For example,
we will use RSET = 10Ω to program 20mA IMAX. In this
example, the user can add 12 more pulses when
changing from 14/32 (8.75mA when IMAX = 20mA) to
2/32 (1.25mA when IMAX = 20mA). However, increasing
the current level can be accomplished by two ways,
allowing for more flexible programming.
Option 1: send in 24 pulses (19+32-27 = 24);
Option 2: pull low for 3ms and then send in 19 pulses.
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. Please
see the SGM3725 evaluation document for detailed
PCB layout guidelines.
tHIGH > 0.4µs
0.4µs < tLOW < 750µs
tOFF > 3ms
CTRL
tS = 800µs (TYP)
100%
31/32
30/32
4/32
3/32
2/32
1/32
I_LED
OFF
OFF
Figure 4. Output Current Programming via CTRL Pin
SG Micro Corp
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10
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
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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
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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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