LED5000PHR STMicroelectronics, LED5000PHR Datasheet

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LED5000PHR

Manufacturer Part Number
LED5000PHR
Description
Current & Power Monitors & Regulators 3A monolithic Conv 850kHz Synch
Manufacturer
STMicroelectronics
Datasheet

Specifications of LED5000PHR

Rohs
yes
Product
Current Regulators
Supply Voltage - Max
48 V
Supply Voltage - Min
5.5 V
Operating Temperature Range
- 40 C to + 150 C
Mounting Style
SMD/SMT
Package / Case
HPSO-8
Accuracy
+/- 3 %
Input Voltage Range
5.5 V to 48 V
Output Current
23 uA
Sensing Method
High or Low Side
Supply Current
1.7 mA

Available stocks

Company
Part Number
Manufacturer
Quantity
Price
Part Number:
LED5000PHR
Manufacturer:
ISSI
Quantity:
1 001
Features
Applications
Figure 1.
January 2013
This is information on a product in full production.
5.5 V to 48 V operating input voltage range
850 kHz fixed switching frequency
200 mV typ. current sense voltage drop
buck / buck-boost / floating boost topologies
PWM dimming
±
200 mW typical RDS
Peak current mode architecture
Short-circuit protection
Compliant with ceramic output capacitors
Inhibit for zero current consumption
Thermal shutdown
High brightness LED driving
Street lighting
Signage
Halogen bulb replacement
General lighting
GND
3 A monolithic step-down current source with dimming capability
3% output current accuracy over temperature
VIN
DIM
Typical application circuit
CIN
ON
CFLT
7
2
3
LED5000
VIN
DIM
INH
COMP
4
Doc ID 023951 Rev 1
BOOT
1
GND
6
SW
FB
U1
Description
The LED5000 is an 850 kHz fixed switching
frequency monolithic step-down DC-DC converter
designed to operate as a precise constant current
source with an adjustable current capability up to
3 A DC. The embedded PWM dimming circuitry
features LED brightness control. The regulated
output current level is set by connecting a sensing
resistor to the feedback pin. The 200 mV typical
R
terms of efficiency. The size of the overall
application is minimized thanks to the high
switching frequency and its compatibility with
ceramic output capacitors. The device is fully
protected against overheating, overcurrent and
output short-circuit. The LED5000 is available in
an HSOP8 package.
8
5
SENSE
voltage drop enhances performance in
L
RS
COUT
HPSO8
Datasheet
LED5000
production data
AM13485v1
www.st.com
1/51
51

Related parts for LED5000PHR

LED5000PHR Summary of contents

Page 1

A monolithic step-down current source with dimming capability Features ■ 5 operating input voltage range ■ 850 kHz fixed switching frequency ■ 200 mV typ. current sense voltage drop ■ buck / buck-boost / floating ...

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Contents Contents 1 Pin settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...

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LED5000 5.9.2 5.9.3 5.10 Layout considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...

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List of tables List of tables Table 1. Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...

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LED5000 List of figures Figure 1. Typical application circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...

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Pin settings 1 Pin settings 1.1 Pin connection Figure 2. Pin connection (top view) 1.2 Pin description Table 1. Pin description COMP 6/51 HSOP8 Type BOOT Analog circuitry power supply connection ...

Page 7

LED5000 2 Maximum ratings 2.1 Maximum ratings Table 2. Absolute maximum ratings Symbol V Power supply input voltage IN V Inhibit input INH V Dimming input DIM V Comp output COMP BOOT Bootstrap pin SW Switching node V Feedback voltage ...

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Electrical characteristics 3 Electrical characteristics All tests performed at T specification is guaranteed from (-40 to +125) T characterization and statistical correlation. Table 5. Electrical characteristics Symbol Parameter Operating input V IN voltage range MOSFET on R DS(on) resistance Maximum ...

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LED5000 Table 5. Electrical characteristics (continued) Symbol Parameter Dimming V Dimming levels DIM Error amplifier High level output V OH voltage Low level output V OL voltage I Source output current o source I Sink output current o sink I ...

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Functional description 4 Functional description The LED5000 is based on a “peak current mode” architecture with fixed frequency control consequence the intersection between the error amplifier output and the sensed inductor current generates the control signal to drive ...

Page 11

LED5000 4.1 Power supply and voltage reference The internal regulator circuit consists of a startup circuit, an internal voltage pre-regulator, the bandgap voltage reference and the bias block that provides current to all the blocks. The starter supplies the startup ...

Page 12

Functional description During normal operation a new soft-start cycle takes place in case of: ● thermal shutdown event ● UVLO event The soft-start is disabled during the dimming operation to maximize the dimming performance. 4.4 Dimming block The DIM input ...

Page 13

LED5000 5 Application notes - buck conversion 5.1 Closing the loop Figure 6. Block diagram of the loop PWM control Current sense PWM comparator 5.2 G (s) control to output transfer function CO The accurate control to output transfer function ...

Page 14

Application notes - buck conversion Equation 2 Equation 3 where: Equation 4 S represents the slope of the sensed inductor current peak to peak amplitude) that implements the slope compensation to avoid sub- PP harmonic oscillations at ...

Page 15

LED5000 Figure 7. Transconductance embedded error amplifier and C introduce a pole and a zero in the open loop gain system stability but it can be useful to reduce the noise at the ...

Page 16

Application notes - buck conversion 5.4 LED small signal model Once the system reaches the working condition the LEDs composing the row are biased and their equivalent circuit can be considered as a resistor for frequencies << 1 MHz. The ...

Page 17

LED5000 Figure 9. Load equivalent circuit As a consequence the LED equivalent circuit gives the voltage with the high impedance FB input: Equation 13 5.5 Total loop gain In summary, the open loop gain can be expressed as: Equation 14 ...

Page 18

Application notes - buck conversion With the power components selected in accordance with and given the BW specification, the components composing the compensation network can be calculated as: Equation 16 where the term m ( Equation ...

Page 19

LED5000 Equation 21 The gain and phase margin bode diagrams are plotted, respectively, in Figure 11 . Figure 10. Module plot 100 0.1 Figure 11. Phase plot 180 157.5 135 ...

Page 20

Application notes - buck conversion The cut-off frequency and the phase margin are: Equation 22 5.8 Dimming operation The dimming input disables the switching activity, masking the PWM comparator output. The inductor current dynamic performance when dimming input goes high ...

Page 21

LED5000 Figure 13. LED rising edge operation Figure 14. LED rising edge operation (zoom) Application notes - buck conversion Doc ID 023951 Rev 1 AM13497v1 AM13498v1 21/51 ...

Page 22

Application notes - buck conversion 5.8.1 Dimming frequency vs. dimming depth As seen in Chapter 5.8 system bandwidth (T The dimming performance depends on the minimum current pulse shape specification of the final application. The ideal minimum current pulse has ...

Page 23

LED5000 the external power components and the compensation network are selected, a direct measurement to determine T achieved dimming performance. 5.9 Component selection 5.9.1 Sensing resistor In closed loop operation the LED5000 feedback pin voltage is 200 mV, so the ...

Page 24

Application notes - buck conversion The LED ripple current can be calculated as the inductor ripple current ratio flowing into the output impedance using the Laplace transform (see Equation 27 where the term 8/ 2 represents the main harmonic of ...

Page 25

LED5000 Equation 32 which is satisfied selecting a10 H inductor value. The output capacitor value has to be dimensioned according to Finally, given the selected inductor value ceramic capacitor value keeps the LED current ripple ratio lower ...

Page 26

Application notes - buck conversion Equation 35 Where V is the free wheeling diode forward voltage and V F internal PDMOS. Considering the range D I going through the input capacitor. Capacitors that can be considered are: RMS ● Electrolytic ...

Page 27

LED5000 The input and output loops are minimized to avoid radiation and high frequency resonance problems. The feedback pin to the sensing resistor path must be designed as short as possible to avoid pick-up noise. Another important issue is the ...

Page 28

Application notes - buck conversion higher than this value to compensate for the losses in the overall application. For this reason, the conduction losses related to the R ● Switching losses due to turning ON and OFF. These are derived ...

Page 29

LED5000 For the calculation we can estimate R during the operation approximately 12 ns. SW_EQ I has a typical value of 2 The overall internal losses are: Equation 41 P TOT Equation 42 P ...

Page 30

Application notes - buck conversion Equation 45 where DCR is the series resistance of the inductor and V L drop across the external rectifying diode. The pulse-by-pulse current limitation is effective to implement constant current protection when: Equation 46 Equation ...

Page 31

LED5000 Figure 19. constant current protection triggering hiccup mode 5.13 Application circuit Figure 20. Evaluation board application circuit TP1 DIM TP2 VIN INH TP8 C1 C2 10uF 10uF 50V 50V TP3 GND The network D3, R4, RS implements an inexpensive ...

Page 32

Application notes - buck conversion Equation 49 R1 must be dimensioned to limit the D1 rated power inexpensive small signal Zener diode. The overvoltage limits the output voltage in case of LED disconnection so protecting LEDs ...

Page 33

LED5000 Figure 21. PCB layout (component side) Figure 22. PCB layout (bottom side) Application notes - buck conversion Doc ID 023951 Rev 1 AM13505v1 AM13506v1 33/51 ...

Page 34

Application notes - alternative topologies 6 Application notes - alternative topologies Thanks to the wide input voltage range, the adjustable external compensation network and enhanced dimming capability, the LED5000 is suitable to implement boost and buck-boost topologies. 6.1 Inverting buck-boost ...

Page 35

LED5000 Since the maximum operating voltage of the LED5000 according to maximum input voltage of the application is 48-18.7=29.3 V The output voltage is given by: Equation 52 where the ideal duty cycle D Equation 53 However, ...

Page 36

Application notes - alternative topologies Figure 24. LED current source based on inverting BB topology TP1 VIN TP3 DIM C2 C3 10uF 10uF 50V 50V TP4 GND The circuitry Q1, R2, R3, R4 implements a level shifter to convert the ...

Page 37

LED5000 Equation 57 R1 must be dimensioned to limit the D1 rated power inexpensive small signal Zener diode. The overvoltage protection plays an important role for the inverting buck-boost topology. In fact, in case of open ...

Page 38

Application notes - alternative topologies 6.2 Positive buck-boost Positive buck-boost fits those applications that require a buck-boost topology (i.e. the input voltage range crosses the output voltage value) and where the inverting buck-boost is not suitable because of the main ...

Page 39

LED5000 Equation 61 This is due to the fact that the current flowing through the internal power switch is delivered to the output only during the OFF phase. The switch peak current must be lower than the minimum current limit ...

Page 40

Application notes - alternative topologies In case of open row, the positive output voltage tends to diverge, exceeding the D3 maximum reverse voltage and so the diode would be damaged. The overvoltage protection limits V and it protects the power ...

Page 41

LED5000 Equation 66 where V is the minimum operating voltage. OP_MIN The equations for the floating boost are: Equation 67 The ideal duty cycle D Equation 68 As seen for the buck-boost topologies ( the real duty cycle is always ...

Page 42

Application notes - alternative topologies Figure 31 shows the circuit schematic for an LED current source based on the floating boost topology. The input voltage ranges from and it can drive a string composed of 11 ...

Page 43

LED5000 Figure 32. Floating BB dimming operation To design the compensation network for the boost topology please refer to paragraph Chapter 6.4: Compensation network design for alternative topologies Figure 33. Floating boost PCB layout (component side) Figure 34. Floating boost ...

Page 44

Application notes - alternative topologies 6.4 Compensation network design for alternative topologies The small signal analysis for the alternative topologies can be written as: Equation 74 G that shares similar terms with addition K depends on the topology (different for ...

Page 45

LED5000 Equation 78 Table 10. BB and boost parameters R K LOAD --------------------- - V OUT ----------------- I LED -------------------------------------------------------------------------------------------------------------------------------------------------- K m 0.5 D – 0.5 6.4.1 f < case the ...

Page 46

Application notes - alternative topologies Equation 80 where K represents the leading position of the F bandwidth. In general a decade (K=10) gives enough phase margin to the overall small loop transfer function. 6.4.2 f > case ...

Page 47

LED5000 7 Package mechanical data In order to meet environmental requirements, ST offers these devices in different grades of ® ECOPACK packages, depending on their level of environmental compliance. ECOPACK specifications, grade definitions and product status are available at: ® ...

Page 48

Package mechanical data Figure 35. Package dimensions 48/51 Doc ID 023951 Rev 1 LED5000 7195016_D ...

Page 49

... LED5000 8 Ordering information Table 12. Order code Order code LED5000PHR Package HPSO8 Doc ID 023951 Rev 1 Ordering information Packing Tube 49/51 ...

Page 50

Revision history 9 Revision history Table 13. Document revision history Date 31-Jan-2013 50/51 Revision 1 Initial release. Doc ID 023951 Rev 1 LED5000 Changes ...

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... LED5000 Information in this document is provided solely in connection with ST products. STMicroelectronics NV and its subsidiaries (“ST”) reserve the right to make changes, corrections, modifications or improvements, to this document, and the products and services described herein at any time, without notice. All ST products are sold pursuant to ST’s terms and conditions of sale. ...

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