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PDF IRS2980S Data sheet ( Hoja de datos )
| Número de pieza | IRS2980S | |
| Descripción | LED DRIVER CONTROL IC | |
| Fabricantes | International Rectifier | |
| Logotipo |  |
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January 20th, 2012
IRS2980S
LED DRIVER CONTROL IC
IC Features
• Dimming LED driver controller
• Hysteretic Current Regulation
• Closed-loop LED current dimming control
• Analog/PWM Dimming Input
• Internal High Voltage Regulator
• Internal 15.6V zener clamp diode on Vcc
• Micropower startup (250μA)
• Latch immunity and ESD protection
LED Driver System Features
• Single chip dimming solution
• Simple LED current dimming control method
• No external protection circuits required (fully
internal)
• Low external component count
• Easy to use for fast design cycle time
• Increased manufacturability and reliability
Product Summary
Topology
VOFFSET (breakdown)
VOUT
IO+ & IO- (typical)
Package Types
Buck
600 V
VCC
180mA & 260mA
SO8
Typical applications
• LED incandescent/CFL replacement lamps
• LED driver module
Typical Connection Diagram
www.irf.com
© 2011 International Rectifier
1
Free Datasheet http://www.Datasheet4U.com
1 page  
IRS2980S
Absolute Maximum Ratings
Absolute Maximum Ratings indicate sustained limits beyond which damage to the device may occur. All
voltage parameters are absolute voltages referenced to COM; all currents are defined positive into any lead.
The Thermal Resistance and Power Dissipation ratings are measured under board mounted and still air
conditions.
Symbol
VHV
VOUT
VADIM
VRAMP
ICC
IOMAX
PD
RθJA
TJ
TS
TL
Definition
High Voltage Input†
Low-Side Output Voltage
DIM Input Voltage
RAMP Input Voltage
Supply Current††
Maximum allowable current at OUT due to external
power transistor Miller effect.
Maximum Power Dissipation @ TA ≤ +25ºC†††
Thermal Resistance, Junction to Ambient
Junction Temperature
Storage Temperature
Lead Temperature (Soldering, 10 seconds)
Min.
-0.3
-0.3
-0.3
-0.3
---
-500
---
---
-55
-55
---
Max.
450
VCC + 0.3
VCC + 0.3
VCC + 0.3
20
500
0.625
128
150
150
300
Units
V
mA
W
ºC/W
ºC
† The IRS2980S uses an HVIC process capable of withstanding up to 600V, however the internal
regulator maximum input voltage rating is limited to 450V maximum due to package power
dissipation. The device can withstand transient voltages up to 600V for short periods.
†† This IC contains a zener clamp structure between the chip VCC and COM which has a nominal
breakdown voltage of 15.6V. This supply pin should not be driven by a DC, low impedance power
source greater than the VCLAMP specified in the Electrical Characteristics section.
††† Power dissipation is dependent on VHV and switching frequency. In order to limit device
temperature rise some thermal relief may be required in the form of copper on the PCB located
under and around the device. Alternatively a small heat sink may be attached to the top of the
device. Thermally conductive potting compounds can also provide excellent heat transfer.
www.irf.com
© 2011 International Rectifier
5
Free Datasheet http://www.Datasheet4U.com
5 Page 
IRS2980S
Application Information and Additional
Details
The IRS2980S is primarily intended for use in
Buck LED drivers operating with average current
regulation using hysteretic control. The circuit
topology uses a low side MOSFET referenced to
the 0V bus driven by a low side gate driver circuit
within the IRS2980S and an additional fast
recovery freewheeling diode. In order to minimize
switching losses the reverse recovery time of this
diode should be no more than 35nS. The
MOSFET should be selected for low capacitance
to reduce switching losses and low gate charge
(less than 25nC is recommended) to minimize
gate drive current. The LED load is referenced to
the DC bus and not 0V. The IRS2980S
incorporates floating high side current sense
inputs allowing the LED current to be sensed both
when the MOSFET is switched on and off. This
enables hysteretic operation, switching the
MOSFET off when the current rises above an
upper threshold and off when the current falls
below a lower threshold.
The current sense threshold Vcs is nominally
500mV with approximately 100mV of hysteresis
making the upper limit Vcs+50mV and the lower
limit Vcs-50mV. Some overshoot typically occurs
due to propagation delays and a small undershoot
is also possible. These vary depending on di/dt of
the ripple current, which is a function of input and
output voltage, inductor value and frequency as
well as RC filter values (RF and CF). The average
current is maintained at approximately the mid-
point over a wide input and output voltage range
due to the inherent accuracy of hysteretic control.
The LED output current is set by selecting the
value of the current sense resistor RCS. This is
determined by the formula:
operating conditions imposed by the input and
output voltages, output current and inductor value.
The following diagram shows the rise and fall of
the LED current as the MOSFET switches on and
off:
Figure 1: MOSFET gate drive and inductor/LED
current.
The following formulae model the operation of the
IRS2980S based Buck LED driver:
ton
≈ 0.2 ⋅ L ⋅ I LED
VBUS _ DC − VLED
+ RF
⋅CF
+
QG
0.18
+
tdr
toff
≈ 0.2 ⋅ L ⋅ I LED
VLED
+ RF ⋅CF
+
QG
0.26
+
tdf
f SW
=
ton
1
+ toff
(switching frequency)
d = ton (duty cycle)
ton + toff
RCS
=
VCS
I LED
Where ILED is the average LED output current.
The peak to peak ripple ∆ILED will be 20% of the
average LED current ILED due to the hysteretic
operation plus some additional ripple due to circuit
delays. These are caused mainly by the current
sense filter and MOSFET gate drive.
Since the IRS2980S uses hysteretic current
control to switch the Buck MOSFET on and off,
the LED current (which is equal to the inductor
current) is maintained between upper and lower
thresholds. Because of this the switching
frequency and duty cycle vary to meet the
Where,
RF and CF are the current sense filter
components,
L is the inductor value,
QG is the MOSFET gate charge,
tdr and tdf are propagation delays
(These values vary depending on circuit
conditions, tdr decreases with input voltage. tdf is
normally negligible. For a first order approximation
these terms may be ignored.)
www.irf.com
© 2011 International Rectifier
11
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11 Page | ||
| Páginas | Total 18 Páginas | |
| PDF Descargar | [ Datasheet IRS2980S.PDF ] | |
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