Texas Instruments TPS92512EVM-001 User manual

User's Guide
SLVUAC9A–February 2015–Revised July 2015
TPS92512EVM-001 High-Current Buck Regulator With
Analog and PWM Dimming for High Brightness LEDs
1 Introduction
The TPS92512EVM-001 evaluation module (EVM) helps designers evaluate the operation and
performance of the TPS92512HV buck switching regulator designed for high-current LED-drive
applications. The TPS92512HV device is designed to control the drive of high-brightness light emitting
diodes and features a wide input voltage range (4.5 V to 60 V), PWM dimming capability, analog dimming
capability, adjustable/syncable switching frequency, and input undervoltage protection.
2 Warnings
Observe the following precautions when using the TPS92512EVM-001.
WARNING
DO NOT STARE DIRECTLY INTO THE LED LIGHT SOURCE. Intense
light sources have a high-secondary blinding effect. A temporary
reduction in visual acuity and afterimages can occur, leading to
irritation, annoyance, visual impairment, and even
accidents—depending on the situation. Always consider the use of
light filtering and darkening protective eyewear and be fully aware
of surrounding laboratory-type set-ups when viewing intense light
sources to minimize or eliminate such risks in order to avoid
accidents related to temporary blindness.
WARNING
Do not stare at the operating LED (Risk Group1 [RG1]). See
IEC32471-1 ed1.0:2009-08 for risk group definitions.
3 Description
The TPS92512EVM-001 provides a high-brightness LED driver based on the TPS92512HV buck
regulator. It is designed to operate with an input voltage in the range of 12 V to 48 V. The EVM is set up
for a default output current of 1.5 A for an LED stack between approximately 5 V and 25 V. The
TPS92512 device helps provide high efficiency, good line regulation, low output ripple, and a wide
dimming range.
3.1 Typical Applications
This converter design describes an application of the TPS92512HV device as an LED driver with the
specifications described in Table 1. For applications with a different input voltage range or different output
voltage range refer to the TPS92512 data sheet.
1
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Description www.ti.com
3.2 Features
3.2.1 Connector Description
This section describes the connectors and test points on the EVM and how to properly connect, setup,
and use the TPS92512EVM-001.
3.2.1.1 J1, LED+, LED-
The screw-down connector, J1, and the test posts marked LED+ and LED- are for connecting the LED
load to the board. The leads to the LED load should be twisted and kept as short as possible to minimize
voltage drop, inductance, and EMI transmission. This design is for approximately 2 to 7 white LEDs.
3.2.1.2 J2, VIN, GND
The screw-down connector, J2, and the test posts marked VIN and GND are for connecting the EVM to
the DC input voltage supply. The input supply ground should be connected to J2 or the GND test post
directly next to J2. One other GND test point is provided on the board that can also be used for all
purposes but input power.
3.2.1.3 UVLO
The test point UVLO connects directly to the UVLO pin of the TPS92512 device. The voltage range is 0 V
to 4.5 V if driven externally. The UVLO resistor divider should be used for the UVLO function, but the
UVLO voltage can be monitored with this test point. Pulling UVLO to GND will also serve to disable the
part and put it into low power shutdown mode.
3.2.1.4 PDIM
The PDIM test point connects directly to the PDIM pin of the TPS92512 device. Leave open for normal
operation. If PWM dimming is used, apply a square wave with a low level of GND and a high level of
between 2 V and 4.5 V. The dimming frequency range is 100 Hz to 1 kHz.
3.2.1.5 SYNC
The SYNC test point is AC coupled to the RT/CLK pin of the TPS92512 device through a 4.02-kΩresistor
in series with a 470-pF capacitor. Apply a square wave with a low level of GND and a high level of 3.3 V
to synchronize the switching frequency to the applied frequency. The frequency range of SYNC is 200 kHz
to 2 MHz.
3.2.1.6 IADJ
The IADJ test point connects directly to the IADJ pin of the TPS92512 device. The default is pulled high
through a 10M resistor to VIN resulting in an ISENSE voltage of 300mV. The range on the IADJ pin is 180
mV to 1.8 V and the corresponding ISENSE voltage is VIADJ / 6.
3.2.1.7 PH
A large via, labelled PH, is included and sized specifically to receive the probe tip of a standard 10x probe.
Use this via to monitor the switching waveform at the PH pin of the device.
2TPS92512EVM-001 High-Current Buck Regulator With Analog and PWM SLVUAC9A–February 2015–Revised July 2015
Dimming for High Brightness LEDs Submit Documentation Feedback
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VIN
0.01µF
C3
UVLO
GND
4.02k
R6
470pF
C8
1.00k
R4
0.1µF
C1
LED-
LED+
PDIM
0.01µF
C6
IADJ
J1
SYNC
10.0M
R2
1.00k
R1
20.5k
R7
174k
R3
191k
R5
0.1µF
C7
VIN=12VDC - 48VDC
VOUT= 5 - 25V , 1.5A
33µH
L1
CAUTION HOT SURFACE
J2
BOOT 1
VIN
2
UVLO
3
PDIM
4
RT/CLK
5
IADJ
6
ISENSE 7
COMP
8
GND 9
PH 10
PAD 11
U1
TPS92512HV
4.7µF
C5
D2
4.7µF
C2
4.7µF
C4
4.7µF
C9
0.2
R8
GND
D1
www.ti.com Electrical Performance Specifications
4 Electrical Performance Specifications
Table 1. TPS92512EVM-001 Electrical Performance Specifications
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
INPUT CHARACTERISTICS
Voltage range 12 48 V
Maximum input current 1.5 A
Input UVLO setting 11.5 V
OUTPUT CHARACTERISTICS
Output voltage, VOUT LED+ to LED- 5 25 V
Output current 1.425 1.5 1.575 A
Output current ripple 20 mApp
Analog dimming range IADJ = 180 mV to 1.8 V 10:1
PWM dimming range 250-Hz PWM 100:1
SYSTEMS CHARACTERISTICS
Efficiency Input voltage = 24 V, 4 LEDs 93%
Switching frequency 570 kHz
5 Schematic
Figure 1. TPS92512EVM-001 Schematic
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Dimming for High Brightness LEDs
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1.45
1.46
1.47
1.48
1.49
1.5
1.51
1.52
1.53
10 15 20 25 30 35 40 45
LED Current (A)
Input Voltage (V)
C002
70
75
80
85
90
95
100
10 15 20 25 30 35 40 45
Efficiency (%)
Input Voltage (V)
C001
Performance Data and Typical Characteristic Curves www.ti.com
6 Performance Data and Typical Characteristic Curves
Figure 2 through Figure 8 show the typical performance curves for the TPS92512EVM-001. Unless
otherwise noted, VIN = 24 V and 3 LED output.
6.1 Efficiency
Top = 7 LEDs Middle = 4 LEDs Bottom = 2 LEDs
Figure 2. Efficiency vs Input Voltage
6.2 Line Regulation
Figure 3. Output Current vs Input Voltage
4TPS92512EVM-001 High-Current Buck Regulator With Analog and PWM SLVUAC9A–February 2015–Revised July 2015
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0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8
LED Current (A)
IADJ Voltage (V)
C003
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
0 10 20 30 40 50 60 70 80 90 100
LED Current (A)
PDIM Duty Cycle (%)
C004
www.ti.com Performance Data and Typical Characteristic Curves
6.3 PWM Dimming
Figure 4. Output Current vs PWM Duty Cycle (250Hz)
6.4 Analog Dimming
Figure 5. Output Current vs IADJ Voltage
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Performance Data and Typical Characteristic Curves www.ti.com
6.5 PWM Dimming Waveforms
Top = PDIM Bottom = LED Current
Figure 6. 1% Duty Cycle, 250-Hz PWM Dimming
Top = PDIM Bottom = LED Current
Figure 7. 50% Duty Cycle, 250-Hz PWM Dimming
6TPS92512EVM-001 High-Current Buck Regulator With Analog and PWM SLVUAC9A–February 2015–Revised July 2015
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www.ti.com Performance Data and Typical Characteristic Curves
Top = PDIM Bottom = LED Current
Figure 8. 99% Duty Cycle, 250-Hz PWM Dimming
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TPS92512EVM-001 PCB layout www.ti.com
7 TPS92512EVM-001 PCB layout
Figure 9 and Figure 10 show the design of the TPS92512EVM-001 printed circuit board.
Figure 9. Top Layer and Top Overlay (Top View)
Figure 10. Bottom Layer and Bottom Overlay (Bottom View)
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www.ti.com Bill of Materials
8 Bill of Materials
Table 2 lists the TPS92512EVM-001 components list according to the schematic shown in Figure 1.
Table 2. Bill of Materials
REFERENCE QTY VALUE DESCRIPTION SIZE PART NUMBER MFR
DESIGNATOR
C1 1 0.1 µF CAP, CERM, 0.1 µF, 25 V, ±10%, X5R 0603 885012206071 Wurth
C2, C4, C9 3 4.7 µF CAP, CERM, 4.7 µF, 100 V, ± 10%, X7S 1210 C3225X7S2A475K200AB TDK
C3, C6 2 0.01 µF CAP, CERM, 0.01 µF, 100 V, ±10%, X7R 0603 06031C103KAT2A AVX
C5 1 4.7 µF CAP, CERM, 4.7 µF, 25 V, ± 10%, X7R 1206 885012208068 Wurth
C7 1 0.1 µF CAP, CERM, 0.1 µF, 50 V, ± 10%, X7R 0603 885012206095 Wurth
C8 1 470 pF CAP, CERM, 470 pF, 50 V, ±10%, X7R 0603 885012206081 Wurth
D1 1 800 mV at 500 mA DIODE SCHOTTKY 80 V 0.5 A SOD-123 MBR0580-TP Micro Commercial Co
D2 1 850 mV at 2 A DIODE SCHOTTKY 80 V 2 A DO-214AC, SMA CDBA280-G Comchip Technology
L1 1 33 µH Inductor, Shielded Drum Core, Ferrite, 33 1246 744771133 Wurth
µH
J1, J2 2 Connector, rising clamp, 2 pins, 5mm 691123710002 Wurth
pitch
R1, R4 1 1 kΩRES, 1 kΩ, 1%, 0.1W 0603 CRCW06031K00FKEA Vishay-Dale
R2 1 10 MΩRES, 10 MΩ, 1%, 0.1 W 0603 CRCW060310M0FKEA Vishay-Dale
R3 1 174 kΩRES, 174 kΩ, 1%, 0.1 W 0603 CRCW0603174KFKEA Vishay-Dale
R5 1 191 kΩRES, 191 kΩ, 1%, 0.1 W 0603 CRCW0603191KFKEA Vishay-Dale
R6 1 4.02 kΩRES, 4.02 kΩ, 1%, 0.1W 0603 CRCW06034K02FKEA Vishay-Dale
R7 1 20.5 kΩRES, 20.5 kΩ, 1%, 0.1 W 0603 CRCW060320K5FKEA Vishay-Dale
R8 1 0.2 RES, 0.2, 1%, 1 W 2010 CSRN2010FKR200 Stackpole Electronics Inc
U1 1 TPS92512 2.5A Buck Current Regulator DGQ0010D TPS92512HV Texas Instruments
for High-Brightness LEDs with Integrated
Analog Current Adjust
9
SLVUAC9A–February 2015–Revised July 2015 TPS92512EVM-001 High-Current Buck Regulator With Analog and PWM
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Revision History www.ti.com
Revision History
Changes from Original (February 2015) to A Revision .................................................................................................. Page
• Changed the PART NUMBER and MFR of C1, C5, C7, C8, and L1 in Table 2.................................................. 9
• Added J1, J2 to Table 2.................................................................................................................. 9
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
10 Revision History SLVUAC9A–February 2015–Revised July 2015
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