IRS2548D
LED Driver IC
PFC and Half Bridge driver combo
Peter Green – LED Group Mgr
Energy Saving Products Business Unit
April 2011
COMPANY CONFIDENTIAL
1
LED Lighting Introduction
Small LEDs developed in 1960s for indication
High Brightness / High Power LEDs now available
Lumens per Watt better than Incandescent / Halogen
lamps
Lumens per Watt equal or better than Fluorescent or
HID lamps
HB/HP LEDs being adopted in general illumination
Typical applications; bulb replacements, light fixtures,
Street lamps
LEDs have longer operating life, typically 50000 hours
LEDs offer better reliability / durability
LEDs are easier to control and dim
LEDs offer reduced Lumen depreciation
(less light output reduction over time)
LEDs are normally DC driven
LEDs are driven by constant current
COMPANY CONFIDENTIAL
High Power LED Applications
LED Street Light
Typically 120W per cobra head
Example opposite uses 4 x 30W
LED panels
One LED driver per cobra head
Typically 1.4A output
Single or multi channel output
Optimize for efficiency (series LED
connection) or redundancy (4 channel
output)
High Lumen output / directed light
Controllable light output (PWM or linear dimming)
Galvanically isolated low voltage outputs (safety)
Open and short circuit protected
Wide input voltage range 90 to 305VAC
High power factor and low THD
COMPANY CONFIDENTIAL
Power Factor Control is Power Quality
 “Power Factor”

Relationship between voltage and current waveforms

Measure of “power quality” that affects transmission network efficiency
 PFC regulations apply to:

China

Europe : IEC 1000-3-2

Japan

: China Compulsory Certificate (CCC)
: JIC C 61000-3-2
For products >75W (>26W for lighting applications)
COMPANY CONFIDENTIAL
4
IRS2548D
Critical conduction mode (CrCM) PFC Control
THD reduction by on time modulation
Variable frequency oscillator (current controlled)
Half bridge driver
PWM dimming input (ENN) also disables PFC
Over current protection (PFC and Half bridge)
Fixed internal 1.6uS half bridge (HO and LO) dead time
Internal bootstrap MOSFET
Internal 15.6V zener clamp diode on VCC
Micropower startup (250uA)
Latch immunity and ESD protection
Maximum half bridge offset voltage 600V
Gate drive output current (PFC, HO, LO) +/-0.5A
14 lead SOIC package
For LED driver and SMPS applications (typically >
50W)
For wide AC input voltage range 90 to 305 VAC
COMPANY CONFIDENTIAL
IRS2548D Target Applications
Handheld LED
Lamps
OFF LINE LED
LIGHT FIXTURES
AUTOMOTIVE
LCD Back Light
Fluorescent
Replacement
Incandescent
Replacement
HID
Replacement
Handheld
Devices
COMPANY CONFIDENTIAL
Two Stage LED Driver
EMI Filter & Rectifier
L
PFC Boost Converter
Half-Bridge Stage
Output
N
E
IFB
IRS2548D
PFC + Half Bridge Driver IC
Combo IC Solution
COMPANY CONFIDENTIAL
7
IRS2548D Typical Schematic
Bus Voltage Feedback
Frequency Control Input
DPFC
LPFC
RVBUS1
RVCC
RVBUS2
L
F1
RV1
CVBUS
C1
L1
VBUS
N
RPU
BR1
14
2
13
CCO MP
RZX
CY
CVBUS2
C2
3
ZX
4
+
PFC
MPFC
5
RP FC
OC
76
IRS2548D
COMP
GND
MHS
LED+
VS
FMIN
RFMIN
CVBUS1 +
RHO
HO
1
RVBUS
CBS
VB
12
CVS
VCC
RLM2
11
+
COM
10
CVCC 2
9
RD1
MLS
COUT
RF1
CS
CF1
DOUT2
DCP 1
ENN
RV1
CVS
DCP2
CVCC1
RLO
LO
+5V
Reg
RLM1
ROC
7
DOUT1
8
CRES
LED-
RD2
RCS
RFMAX
ROC
CF2
RV2
COC
R CL
CCS
RD3
Half Bridge MOSFETs
PFC MOSFET
OPTO ISOLATOR
(Feedback)
Rectifier
Diodes/MOSFETs
Voltage and
Current
Feedback
COMPANY CONFIDENTIAL
IRS2548D Demo Board  IRPLLED5
Features:
High output current regulation
90-305VAC universal input
Dimmable with 1-10V DC input
Non-latched shutdown against
output over-voltage
Using IRS2548DS
LED control IC
COMPANY CONFIDENTIAL
Test Results
Load: 2 x Eco Lumens EPAD connected in series
Pin
(W)
PF
THDi
(%)
Fs
(kHz)
Vout
(Vdc)
Iout
(Adc)
Pout
(W)
Eff
(%)
100
55.1
0.999
2.3
42.8
39.2
1.22
47.8
86.8
120
55.4
0.998
6.4
42.8
39.1
1.23
48.1
86.8
220
55.0
0.979
13.1
42.8
39.1
1.24
48.5
88.2
240
55.1
0.972
15.6
42.8
39.1
1.24
48.5
88.0
277
55.5
0.952
18.3
42.8
39.1
1.25
48.9
88.1
VACin
(Vrms)
Driving
32 x Samsung Sunnix6
HPLED packs
Total Power = 55W
COMPANY CONFIDENTIAL
Output V-I Characteristic
Voltage vs Current
60
Voltage (V)
50
40
30
V-I
20
10
Current (A)
1.
6
1.
4
1.
2
1
0.
8
0.
6
0.
4
0.
2
0
0
Green = LED Voltage
Blue = LED Current
Open circuit voltage < 60V
Current ripple ~15%
Short circuit current = 1.5A
COMPANY CONFIDENTIAL
Multi Channel LED Concept
90 to
305VAC
50/60Hz
~
700mA
+48V
EMI filter/
Rectification
PFC
Isolation
Voltage
Control
0V
2 Channel
700mA
Driver
Power Converter
IRS2548D Based
Power Stage
One main power converter supplies 48V
isolated DC bus
Wide input voltage range 90 to 305VAC
High power factor and low THD
Output modules provide 2 x 700mA
regulated current outputs
2 Channel
Driver
2 Channel
Driver
COMPANY CONFIDENTIAL
IRS2548D IC Summary
For LED driver and SMPS applications (typically > 50W)
For wide AC input voltage range 90 to 305 VAC
High Power Factor and Low THD
Resonant Half Bridge Topology / Soft Switching
Efficiency better than 85% above 50W
Efficiency improves at higher power levels
Suitable for isolated LED drivers > 50W
Efficiency and flexibility surpasses Flyback solution above 50W
Protected against short circuit in primary and secondary stages
Enables regulated output current loop for LED driving
Incorporates PWM dimming input, allows dimming to ~2% output
COMPANY CONFIDENTIAL