User's Guide
SNVA284A – March 2008 – Revised April 2013
AN-1702 LP5524 Evaluation Kit
1
LP5524 Overview
The LP5524 is a highly integrated dual-zone LED driver that can drive up to four LEDs in parallel with a
total output current of 100 mA. Regulated high side internal current sources deliver excellent current and
brightness matching in all LEDs. Extremely low minimum headroom voltage allows the use of operating
voltages that are close to LED forward voltages.
LED driver current sources are split into two independently controlled banks for driving secondary
displays, keypads and indicator LEDs. Brightness control is achieved by applying PWM signals to each
enable pin. Default LED current is 5mA and an optional external resistor can be used to set initial
brightness to user required values. LP5524 is available in TI’s tiny 9-bump DSBGA package.
2
Evaluation Kit Overview
LP5524 evaluation kit enables designers an easy way to evaluate the performance of the device. The
evaluation board has jumpers for each enable pin for easy on/off type control. These inputs can also be
fed with external PWM source. Jumpers on LED outputs allow easy LED current measuring. ISET pin has
a jumper for selecting between two LED current levels.
The kit supports complete functional evaluation of the circuit. The evaluation kit consists of:
• LP5524 Evaluation Board
• LP5524 Parallel LED Driver With PWM Brightness Control in DSBGA Package Data Sheet (SNVS500)
• Evaluation Kit document (this document)
All trademarks are the property of their respective owners.
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1
Evaluation Kit Overview
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Figure 1. LP5524 Evaluation Board
2
AN-1702 LP5524 Evaluation Kit
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Jumper Description
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3
Jumper Description
This describes the jumpers and the connectors on the LP5524 evaluation board.
Figure 2. LP5524 Evaluation Board Top View
VIN – J1
This connector is the positive input for power supply. The evaluation board can operate with supply
voltages from 2.7 V to 5.5 V. The input leads from power supply should be twisted and kept as short as
possible. There is an input capacitor (C1) on board to smooth the input voltage.
GND – J4
This is the negative input for power supply.
J2
This jumper disconnects all LED cathodes from the GND. This can be used to separate the LED currents
from the circuit current.
D1B – J6
This jumper can be used to disconnect the D1B output from the LED anode. This can be used to measure
the D1B current.
D2B - J3
This jumper can be used to disconnect the D2B output from the LED anode. This can be used to measure
the D2B current.
D2A – J7
This jumper can be used to disconnect the D2A output from the LED anode. This can be used to measure
the D2A current.
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Getting Started
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D1A – J5
This jumper can be used to disconnect the D1A output from the LED anode. This can be used to measure
the D1A current.
D2A – J7
This jumper can be used to disconnect the D2A output from the LED anode. This can be used to measure
the D2A current.
ENB – J8
This is the ENB input. A three pin connector is applied to allow ENB to be connected either to VIN or to
GND. The center pin is connected directly to ENB pin. This pin can be used to connect external PWM
signal. Smaller than 300 Hz PWM frequency is recommended.
ISET – J10
ISET pin jumper. This can be used to connect the ISET pin either to VIN or to onboard RISET resistor.
Connecting ISET to VIN sets the LED current to default 5mA and connecting it to RISET sets the current to
15.6 mA. Center pin is connected directly to ISET pin and it can be used to connect external current set
resistors.
ENA – J9
This is the ENA input. A three pin connector is applied to allow ENA to be connected either to VIN or to
GND. The center pin is connected directly to ENA pin. This pin can be used to connect external PWM
signal. Smaller than 300 Hz PWM frequency is recommended.
4
Getting Started
The following instructions show how to set up and use the LP5524 evaluation kit. Use ESD protection to
prevent any unwanted damaging ESD events.
1. Check the onboard jumpers. Jumpers on the LED outputs (J3, J5-J7) and the jumper from LED
cathodes to gnd (J2) should be on. Remove jumpers from enables (J8 and J9). ISET can be connected
either to VDD or RISET.
2. Connect evaluation board to a power supply. Check that operation voltage is between 2.7 V to 5.5 V.
3. Set the enable jumpers to ON position. ENA jumper enables drivers D1A and D2A and ENB jumper
enables drivers D1B and D2B.
4. The Evaluation Kit is now ready to use.
4.1
Current Measurements
To measure the current of a single LED driver remove the jumper from that driver's output and connect
current meter to jumper's pins. To measure the current of all LEDs remove the J2 jumper and connect
current meter to J2 pins. To measure the current consumption of the device separate the LED ground
current from the board's ground current by removing the J2 jumper and conecting the LED ground to
power supply ground with separated wire. Then connect the current meter to evaluation board's ground
wire. Figure 3 illustrates how to measure different currents.
4
AN-1702 LP5524 Evaluation Kit
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Board Layout
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4.2
PWM Dimming
To dim the LEDs, feed a proper PWM signal to ENx pin. Less than 300 Hz PWM frequency is
recommended. Ensure that the PWM signals are high and that the low levels are adequate.
Figure 3. LP5524 Evaluation Board Current Measurements
5
Board Layout
A four layer board was used to enable the use of micro-VIAs. Micro VIA is required for routing the center
pad of the LP5524. The evaluation board layers are:
• Top, component side, signal
• Layer 2, VIN plane (signal)
• Layer 3, GND plane
• Bottom, GND plane
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Board Layout
6
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Figure 4. LP5524 Evaluation Board Layer 1 (Top).
Figure 5. LP5524 Evaluation Board Layer 2.
Figure 6. LP5524 Evaluation Board Layer 3.
Figure 7. LP5524 Evaluation Board Layer 4 (Bottom)
AN-1702 LP5524 Evaluation Kit
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Schematic
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6
Schematic
U1
B2
VIN
A3
ENA
J7
B1
J6
C1
J3
D3
LP5524
A2
1
2 3
C3
D2A
J9
ENB
1
2 3
J8
C1
0.1 PF
J5
D4
2 3
J4
VIN
B3
D1A
D1B
D2
A1
ISET
D2B
GND
J10
1
J1
GND
D1
C2
J2
R1
33 k:
GND
GND
GND
GND
GND
Figure 8. LP5524 Evaluation Board Schematic
7
List of Components
Reference
Model
Type
Vendor
Size
C1
100 nF 10 V
Ceramic X5R
TDK
0402 (1005)
R1
33kΩ 1%
-
-
0402 (1005)
D1 -D4
LS T676
LED Red
Osram
3.0 mm x 3.4 mm x 2.1 mm
U1
LP5524
-
TI
1.215 mm x 1.215 mm x 0.6 mm
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