NXP Semiconductors UM10694 User manual

UM10694
SSL2109ADB1107 - 230 V/7 W GU10 high PF isolated LED
driver demo board
R
ev. 1 — 9 April 2013
User manual
Document information
Info Content
Keywords SSL2109ADB1107, flyback converter, high power factor, GU10
Abstract This document describes the operation of a 230 V/7 W non-dimmable
LED driver demo board featuring SSL2109A and using an isolated
flyback topology. The SSL2109ADB1107 demo board is designed for
GU10 form factors used in Solid State Lighting (SSL) applications.

NXP Semiconductors
UM10694
SSL2109ADB1107 - 230 V/7 W GU10 high PF isolated LED driver
UM10694
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2013. All rights reserved.
User manual
Rev. 1 — 9 April 2013
2 of 21
Revision history
Rev
Date
Description
v. 1
20130409
first issue

NXP Semiconductors
UM10694
SSL2109ADB1107 - 230 V/7 W GU10 high PF isolated LED driver
UM10694
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2013. All rights reserved.
User manual
Rev. 1 — 9 April 2013
3 of 21
1. Introduction
This user manual describes the operation of the SSL2109ADB1107 demo board
featuring the SSL LED driver SSL2109A in a 230 V/7 W isolated flyback converter
application.
The SSL2109ADB1107 demo board is designed for driving a 3-LED string load.
The PCB dimensions are compatible with GU10 form factors used in SSL applications.
The demo board provides a simple and effective solution having a power factor greater
than 0.9 and efficiency up to 85 % for SSL applications.
1.1 Features of the application
•GU10 form factor compatibility
•Open LED and short circuit LED string protection
•OverCurrent protection (OCP) and OverTemperature protection (OTP)
•Power factor (PF) greater than 0.9 and THD < 20 %
•Efficiency up to 85 %
•Compliant with IEC61000-3-2 harmonics standard
The assembled top and bottom board views are shown in Fig 1 with the board
dimensions in Fig 3. The board dimensions allow enough headroom with GU10 lamps.

NXP Semiconductors
UM10694
SSL2109ADB1107 - 230 V/7 W GU10 high PF isolated LED driver
UM10694
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2013. All rights reserved.
User manual
Rev. 1 — 9 April 2013
4 of 21
a. Top view
b. Bottom view
Fig 1. SSL2109ADB1107 230 V/7 W GU10 demo board

NXP Semiconductors
UM10694
SSL2109ADB1107 - 230 V/7 W GU10 high PF isolated LED driver
UM10694
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2013. All rights reserved.
User manual
Rev. 1 — 9 April 2013
5 of 21
2. Safety
The board is connected to mains voltage. Avoid touching the demo board while it is
connected to the mains voltage. An isolated housing is obligatory when used in
uncontrolled, non-laboratory environments. Galvanic isolation of the mains phase using a
variable transformer is always recommended.
a. Isolated
b. Not isolated
Fig 2. Variable transformer isolation symbols

NXP Semiconductors
UM10694
SSL2109ADB1107 - 230 V/7 W GU10 high PF isolated LED driver
UM10694
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2013. All rights reserved.
User manual
Rev. 1 — 9 April 2013
6 of 21
3. Specifications
Table 1. Specifications of the SSL2109ADB1107
Symbol
Parameter
Value
Vmains AC mains supply voltage 230 V; ±10 %
Pin input power 6.9 W at nominal Vmains = 230 V
Pout output power 5.9 W
VLED output voltage (LED voltage) 8 V to 14 V with nominal VLED = 10.8 V
ILED output current (LED current) 550 mA
Iripple output ripple current 215 mA (p-p)
∆
ILED/
∆
Vmains line regulation 0.6 mA/V
(±2.5 %; ILED at ±10 % Vmains variation)
∆
ILED/
∆
VLED load regulation 4 mA/V
(±1 %; ILED at ±10 % VLED variation)
η
efficiency 85 %
PF
power factor
0.92
THD
total harmonic distortion
19 %
fsw switching frequency 70 kHz
Fig 3. SSL2109ADB1107 demo board dimensions

NXP Semiconductors
UM10694
SSL2109ADB1107 - 230 V/7 W GU10 high PF isolated LED driver
UM10694
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2013. All rights reserved.
User manual
Rev. 1 — 9 April 2013
7 of 21
4. Functional description
4.1 Input filtering
A differential mode πfilter is implemented to reduce differential mode noise originating
from the High-frequency (HF) switching currents/voltages in the primary of the converter
from returning to the mains. This noise must be kept to a minimum by:
•Small primary current loop (C2 to pin 5 of T1, pin 3 of T1 to drain of external
MOSFET Q5, ground return from sense resistors R1, R24, R26 to C2 ground)
•Snubber components D3, R17, C8 closely parallel to pins 5 and 3 of T1
•Track length from pin 3 of T1 to drain of external MOSFET to be small in order to
reduce capacitance to surroundings
For this 7 W application, C2 must be chosen sufficiently large to act as a buffer for the HF
current flowing in the primary but also small enough to maintain a high PF where a value
of 100 nF for C2 is a good compromise.
4.2 PF adjustment
The divider network consisting of R5, R6, R7, R9, R10, D4, C10 and C11 modulates the
base of Q7 according to the rectified mains. Consequently, a modulating current set by
R11 flows through R8 and the sense current through R1, R24 and R26 is also
modulated. Depending on the divider resistor values, the HF current through the primary
has a current with a rectified mains modulation resulting in a high PF.
The PF can be increased/decreased by decreasing/increasing R5 and R6 and a
compromise can be reached between PF and line regulation.
4.3 RCD clamp
Leakage inductance of the transformer is in series with primary inductance and the drain
of MOSFET Q5. This leakage inductance together with the parasitic capacitance across
the drain source of Q5 causes HF ringing when Q5 switches off. If the leakage is not
minimized the voltage at the drain reaches high voltages levels which can damage Q5 if
voltage levels exceed the maximum allowable level.
An RCD clamp (R17, C8 and D3) prevents the voltage on the drain of Q5 exceeding the
maximum drain voltage when Q5 switches off.
4.4 Supply voltage
The supply voltage of the SSL2109A is achieved using an auxiliary winding. As further
advantages, the auxiliary winding provides, via a resistor R25 on its underwinding, both a
simple solution for improved load regulation using R12 and open-circuit protection (OCP)
via the NTC pin using R13.
4.4.1 Open-circuit protection
If no LED string is connected to the converter output, the voltage can quickly exceed the
maximum rating of the output capacitors C3 and C13.
The underwinding of the auxiliary is connected to resistor R25 to prevent this. The
voltage across R25 decreases as the output voltage increases. Consequently, the
voltage at the NTC pin decreases once the current through R13 exceeds the internal
current of the NTC pin. When the NTC voltage drops below 0.35 V then the SSL2109A
switches off.

NXP Semiconductors
UM10694
SSL2109ADB1107 - 230 V/7 W GU10 high PF isolated LED driver
UM10694
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2013. All rights reserved.
User manual
Rev. 1 — 9 April 2013
8 of 21
An external 18 V Zener diode is included at the VCC pin to prevent that the voltage
exceeds 20 V at the VCC pin for this no LED string situation.
4.4.2 Short circuit
When the LED terminals are shorted, the SSL2109A defaults to its maximum
demagnetization time of 36 µs. This prevents that the inductor current ramps up to an
excessively large value while the input power is limited and the SSL2109A enters OPS
protection (latched) mode.
Remark:
Do not try to short-circuit the LED output while the circuit is powered or without
discharging C3. The short-circuit protection is intended for zero-hour short circuit
protection (so a short circuit during first assembly before power is applied).

NXP Semiconductors
UM10694
SSL2109ADB1107 - 230 V/7 W GU10 high PF isolated LED driver
UM10694
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2013. All rights reserved.
User manual
Rev. 1 — 9 April 2013
9 of 21
5. Demo board connections
The SSL2109ADB1107 demo board is supplied with a 230 V, 50 Hz mains supply where
the board connection is shown in Fig 4.
Table 2. Input and output connections
Connector
Function
Remark
L AC MainsL line wire solder connection on
small board
N AC MainsN neutral wire solder connection
on small board
+
LED anode
positive LED wire solder
connection on small board
-
LED cathode
negative LED wire solder
connection on small board
X5 AC mains input AC mains in terminal block
X6 LED load output LED connector 6-way female
for NXP LED load
Remarks:
Make all connections with the input mains supply switched off.
Use a protective shield over application and never touch the board when measuring or
testing.
Connections and testing:
•Connect 3-LED string load to the SSL2109ADB1107 together with power meters at
both inputs and outputs.
•Connect Vmains (230 V (AC)/50 Hz) using an isolating transformer (initially set to 0 V)
to the input connection points of the flyback converter. Alternatively, use an AC
power supply with limited output current capability (for example 200 mA).
•Increase Vmains to 230 V (AC) and measure the different parameters as shown in
Table 3.
Table 3. Input/output parameters SSL2109ADB1107
V
mains
(V)
I
in
(mA)
PF
P
in
(W)
V
LED
(V)
I
LED
(mA)
P
out
(W)
η
230
33
0.92
6.9
10.8
550
5.9
0.85

NXP Semiconductors
UM10694
SSL2109ADB1107 - 230 V/7 W GU10 high PF isolated LED driver
UM10694
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2013. All rights reserved.
User manual
Rev. 1 — 9 April 2013
10 of 21
230V
L
N
3 LEDs
Fig 4. Board connection for SSL2109ADB1107 with 3-string LED load