the application or use of any information, products or services described herein. Customers are advised to obtain the latest version of this device specification before relying on any published information and before
placing orders for products.
Integrated Silicon Solution, Inc. does not recommend the use of any of its products in life support applications where the failure or malfunction of the product can reasonably be expected to cause failure of the life
support system or to significantly affect its safety or effectiveness. Products are not authorized for use in such applications unless Integrated Silicon Solution, Inc. receives written assurance to its satisfaction, that:
a.) the risk of injury or damage has been minimized;
b.) the user assume all such risks; and
c.) potential liability of Integrated Silicon Solution, Inc is adequately protected under the circumstances
Integrated Silicon Solution, Inc. – www.issi.com - 1-800-379-4774
Rev. B, 03/12/2013
1
IS31LT3935
PIN CONFIGURATION
Package
Top View
DFN-10
3x3 (Exposed Pad)
10-LEAD (3mm x 3mm) PLASTIC DFN
EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB
PIN DESCRIPTION –
(PINOUT IS SUBJECT TO CHANGE BASED)
Pin #
1
2
3
4
5
6
7
8
9
10
11
*Note1
Name
VCC
VIN
VSINE
SST
FSET
CS
GATE
RMAG
CAVG
BLD
GND
Type
Power
Input
I/O
Input
I/O
Input
Output
Input
Input
Input
Power
Input power supply pin for the IC
Scaled line input voltage. Used to control the TRIAC bias circuit block.
Scaled line input voltage. Used to shape the inductor current to match line input
voltage.
Soft-start input. Connect a capacitor between this pin and GND to control startup delay
time
Frequency select pin. Connect a resistor between this pin and GND to set the base
operating frequency of the IC.
Inductor current sense input pin.
Gate drive output. Connect to the gate of the power NMOS.
Bleeder current set pin. Connect a resistor between this pin and GND to set the
magnitude of the bleeder current for the TRIAC based dimmer.
Bleeder circuit averaging capacitor. Connect a capacitor between this pin and RMAG
to control the bleeder current average function.
Bleeder current path. Connect this pin to the output of the linear regulator via a diode
to provide bleeder current for the TRIAC dimmer.
Ground connection. Connect the exposed pad to GND to provide the power return for
the IC supply.
Description
*Note 1:
Exposed pad (Pin 11) is GND, must be soldered to GND for the IC to operate.
ORDERING INFORMATION
INDUSTRIAL RANGE: -40°C TO +85°C
Order Part No.
IS31LT3935-DLS2-TR
Package
DFN10 (3x3)
QTY/Reel
2500
Integrated Silicon Solution, Inc. – www.issi.com - 1-800-379-4774
Rev. C, 07/19/2013
2
IS31LT3935
ABSOLUTE MAXIMUM RATINGS
(*NOTE 2)
VCC, VIN, CS, BLD voltage to GND
VSINE, SST, CAVG, RMAG voltage to GND
FSET voltage to GND
GATE Output Current
GATE Output Voltage
ESD Susceptibility:
HBM
MM
Junction Temperature
Storage Temperature
Lead Temperature (Soldering, 10sec)
-0.3V to 7.0V
-0.3V to 2.7V
-0.3V to 1.0V
50mA (RMS)
-0.3V to (VCC+0.3V)
2kV
200V
150°C
-65°C to 150°C
260°C
*Note 2:
1.
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 condition 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.
ELECTRICAL CHARACTERISTICS
T
A
= 25°C,
VCC=5.5V, unless otherwise specified. Minimum and maximum limits are guaranteed through test, by design, or by statistical
correlation.
Symbol
VCC
I
VCC
UVLO
tr
GATE
tf
GATE
I
GATEsrc
I
GATEsnk
V
FSET
T
max
T
hyst
A
gm
V
VSINE
fOSC
tmin
V
RMAG
V
CAVG
I
BLD
I
SST
I
CS
V
VIN
Parameter
Supply voltage
Operating Supply Current
Condition
Min.
3.0
Typ.
500
2.3
2.1
20
20
1
1
0.6
165
25
1000
0.1
Max.
6.0
2.5
Unit
V
µA
V
ns
ns
A
A
V
°C
°C
V/V
mmho
VCC rising
VCC falling
GATE Driver
Gate driver output rise time Cload = 1nF (note 2)
Gate driver output fall time Cload = 1nF (note 2)
GATE driver peak current
V
GATE
= 5V
GATE driver peak current
V
GATE
= 0V
Voltage and Temperature Reference
Voltage on FSET pin
Over-temperature shutdown
threshold
Over-temperature hysteresis
Error Amplifier
Open-loop gain
Transconductance
Maximum voltage on VSINE No external voltage overdrive
pin
With external voltage overdrive
Oscillator
Frequency
R
FSET
= 180kΩ
Minimum on-time
Bleed Circuitry
RMAG voltage
R
RMAG
= 10kΩ; V
VIN
= 0V
CAVG voltage
BLD current
Softstart and Sensing
SST pin output current
CS pin input current
VIN input voltage range
Under-voltage lockout
1.8
1.5
2.0
105
100
1.0
0.3
100
-8
0
10
2.5
V
kHz
Ns
V
V
mA
µA
nA
V
NOTES:
1. 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 under recommended operating conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device
reliability.
2. All parts are production tested at T
A
= 25°C. Other temperature limits are guaranteed by design
3. Guaranteed by design
Integrated Silicon Solution, Inc. – www.issi.com - 1-800-379-4774
Rev. C, 07/19/2013
3
IS31LT3935
TYPICAL PERFORMANCE CHARACTERISTICS
Power Factor vs. Dimming (22V/0.6A Output)
Power Factor vs. Dimming (28V/0.3A Output)
Note: Lab data taken using same dimmer and LEDs
Note: Lab data taken using same dimmer and LEDs
Efficiency vs. Dimming (22V/0.6A Output)
Efficiency vs. Dimming (28V/0.3A Output)
Note: Lab data taken using same dimmer and LEDs
Efficiency is from 120Vrms input to 22Vdc output
Note: Lab data taken using same dimmer and LEDs
Efficiency is from 120Vrms input to 28Vdc output
Integrated Silicon Solution, Inc. – www.issi.com - 1-800-379-4774
Rev. C, 07/19/2013
4
IS31LT3935
Functional Block Diagram
Figure 2
Typical Application Schematic
FUNCTIONAL DESCRIPTION
The IS31LT3935 is a high performance off-line AC/DC
LED controller for dimmable LED retrofit lamps and
luminaries using patent pending dimming technology to
eliminate visible light flicker. It can work with all types of
wall dimmers including leading-edge and trailing-edge
dimmers. The controller can also work when no dimmer
is connected.
The IS31LT3935 uses primary-feedback technology to
remove the need for secondary feedback circuitry while
achieving excellent line and load regulation. It eliminates
the need for external loop compensation components
while maintaining stable overall operating conditions.
Pulse-by-pulse waveform analysis allows for accurate
LED current regulations. On every clock cycle, the
oscillator sends a pulse of minimum on- time to the
control logic. Nominal switching frequency is determined
by the value of the resistor attached between FSET and
ground, with approximately 10% variation due to spread-
spectrum modulation. Provided there is no fault condition
(UV or OT or OC high), the driver will switch the GATE
high. GATE will stay high until V
CS
~= V
VSINE
/10, and will
switch low once that condition is met, or the over current
comparator switches.
The proprietary bleed circuitry provides current such that
TRIAC based dimmers properly switch and more
sophisticated electronic dimmers maintain proper
functionality even in their standby state.
Integrated Silicon Solution, Inc. – www.issi.com - 1-800-379-4774
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