TPS92560DGQ/NOPB [TI]
适用于 MR16 和 AR111 应用的简易 LED 驱动器 | DGQ | 10 | -40 to 125;
| 型号： | TPS92560DGQ/NOPB |
| 厂家： | 
TEXAS INSTRUMENTS |
| 描述： | 适用于 MR16 和 AR111 应用的简易 LED 驱动器 | DGQ | 10 | -40 to 125 驱动 光电二极管 接口集成电路 显示驱动器 驱动程序和接口 |
| 文件： | 总17页 (文件大小：704K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
TPS92560
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SNVS900A –DECEMBER 2012–REVISED JANUARY 2013
SIMPLE LED DRIVER FOR MR16 AND AR111 APPLICATIONS
Check for Samples: TPS92560
1
FEATURES
APPLICATIONS
•
Controlled peak input current to prevent over-
stressing of the electronic transformer
•
•
•
MR16/AR111 LED lamps
Lighting system using electronic transformer
•
Allows either step-up or step-up/down
operation
General lighting systems that require a boost /
SEPIC LED driver
•
•
Compatible to generic electronic transformers
DESCRIPTION
Compatible to magnetic transformers and DC
power supplies
The TPS92560 is a simple LED driver designed to
drive high power LEDs by drawing constant current
from the power source. The device is ideal for MR16
and AR111 applications which need good
compatibility to DC and AC voltages and electronic
transformers. The hysteretic control scheme does not
need control loop compensation while providing the
benefits of fast transient response and high power
factor. The patent pending feedback control method
allows the output power to be determined by the
number of LED used without component change. The
TPS92560 supports both boost and SEPIC
configurations for the use of different LED modules.
•
•
•
•
•
•
•
•
Integrated active low-side input rectifiers
Compact and simple circuit
>85% efficiency (12VDC input)
Power factor > 0.9 (full load with AC input)
Hysteretic control scheme
Output Over-Voltage Protection
Over-temperature Shutdown
10-pin mini SOIC package with exposed pad
TYPICAL APPLICATION
L1
D3
LED
CIN
RADJ1
D1
D2
R1
TPS92560
COUT
Q1
GATE
AC1
PGND
AC2
RADJ2 CADJ
Power
Source
SRC
VCC
SEN
GND
CVCC
VP
CVP
ADJ
RSEN
Typical application circuit of the TPS92560 using boost configuration
1
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
PRODUCTION DATA information is current as of publication date.
Copyright © 2012–2013, Texas Instruments Incorporated
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
TPS92560
SNVS900A –DECEMBER 2012–REVISED JANUARY 2013
www.ti.com
TYPICAL APPLICATION (Continue)
L1
D3
C1
LED
RADJ1
COUT
CIN
R1
D1
D2
TPS92560
Q1
L2
GATE
SRC
VCC
SEN
GND
AC1
PGND
AC2
RADJ2 CADJ
Power
Source
CVCC
VP
CVP
ADJ
RSEN
D4
Typical Application Circuit of the TPS92560 using SEPIC configuration
2
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SNVS900A –DECEMBER 2012–REVISED JANUARY 2013
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
BLOCK DIAGRAM
TPS92560
VP
VCC
LDO
VCC
AC1
AC2
TSD
GATE
DRIVER
GATE
SRC
TJ=165°C
UVLO
VCC < 4.98V
Main Switch
and Rectifier
Control
SEN
VCC
DRV
VCC
DRV
Logic
GND
ADJ
OVP
0.384V
PGND
SVA-30207403
ORDERING INFORMATION
ORDER NUMBER
TPS92560DGQ
TPS92560DGQR
PACKAGE TYPE
NSC PACKAGE DRAWING
SUPPLIED AS
1000 Units on Tape and Reel
4500 Units on Tape and Reel
10L MINI SOIC EXP PAD
MUC10A
Copyright © 2012–2013, Texas Instruments Incorporated
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SNVS900A –DECEMBER 2012–REVISED JANUARY 2013
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10-pin mini SOIC Package
(TOP VIEW)
GATE
AC1
SRC
VCC
SEN
PGND
AC2
VP
GND
ADJ
Package Number MUC10A
SVA-30207405
TERMINAL FUNCTIONS
PIN
DESCRIPTION
NO. NAME
APPLICATION INFORMATION
1
2
3
GATE
SRC
VCC
Gate driver output pin
Gate driver return
Connect to the Gate terminal of the low-side N-channel Power FET
Connect to the Source terminal of the low-side N-channel Power FET
Connect 0.47μF decoupling cap from this pin to SRC pin
VCC regulator output
Kelvin-sense current sensing input. Should connect to the current sensing
resistor, RSEN
4
SEN
Current sense pin
.
5
6
GND
ADJ
Analog ground
Reference point for current sensing.
LED current adjust pin
Connect to resistor divider from LED top voltage rail to set LED current
Connect it to the LED top voltage rail (for boost) or Connect it through a diode
from LED top voltage rail (for SEPIC)
7
VP
Power supply of the IC
8
9
AC2
Power return terminal
Power ground
Connect to AC or DC input terminal
Connect to system ground plane
PGND
AC1
10
Power return terminal
Connect to AC or DC input terminal
Connect to system ground plane for heat dissipation
PowerPAD Thermal DAP
ABSOLUTE MAXIMUM RATINGS(1)
If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for
availability and specifications.
VALUE
–0.3 to 5
–1 to 45
UNIT
SRC, SEN, ADJ
V
V
AC1, AC2
VP
–0.3 to 45
–0.3 to 12
1.5
V
VCC
V
ESD Rating Human Body Model(2)
kV
°C
°C
Storage Temperature
–65 to +150
–40 to +125
TJ
Junction Temperature
(1) Absolute Maximum Ratings are limits which damage to the device may occur. Operating ratings are conditions under which operation of
the device is intended to be functional. For specified specifications and test conditions, see the electrical characteristics.
(2) The human body model is a 100 pF capacitor discharged through a 1.5 kΩ resistor into each pin.
4
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SNVS900A –DECEMBER 2012–REVISED JANUARY 2013
RECOMMENDED OPERATING CONDITIONS
over operating free-air temperature range (unless otherwise noted)
MIN
6.5
NOM
MAX
42
UNIT
V
VP
TJ
Supply voltage range
Junction temperature range
–40
125
°C
(1)
(1)
θJA
θJC
Thermal resistance, Junction to Ambient, 0 LFPM Air Flow
Thermal resistance, Junction to Case
48
10
°C/W
°C/W
(1) θJA and θJC measurements are performed on JEDEC boards in accordance with JESD 51-5 and JESD 51-7
ELECTRICAL CHARACTERISTICS
Specification with standard type are for TA=TJ= 25°C only; limits in boldface type apply over the full Operating Junction
Temperature (TJ) range. Minimum and Maximum are specified through test, design or statistical correlation. Typical values
represent the most likely parametric norm at TJ= 25°C, and are provided for reference purposes only. Unless otherwise stated
the following conditions apply: VVP = 12V
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
SUPPLY
IIN
VIN Operating current
6.5 V < VVP < 42 V
0.7
1.4
1.95
mA
VCC REGULATOR
I
CC ≤ 10mA, CVCC =0.47µF
7.82
8.45
9.08
6.18
12V < VVP < 42V
VCC
VCC Regulated Voltage(1)
V
ICC = 10mA, CVCC =0.47µF VVP = 6.5V
ICC = 0mA, CVCC =0.47µF VVP = 2V
VCC = 0V 6.5V < VVP < 42V
5.22
1.96
21
5.8
2.0
ICC-LIM
VCC Current Limit
30
39
5.76
5.33
640
mA
V
VCC-UVLO-UPTH
VCC-UVLO-LOTH
VCC-UVLO-HYS
VCC UVLO Upper Threshold
VCC UVLO Lower Threshold
VCC UVLO Hysteresis
5.0
5.38
4.98
400
4.63
190
V
mV
MOSFET GATE DRIVER
w.r.t. SRC
VGATE-HIGH Gate Driver Output High
Sinking 100mA from GATE
Force VCC = 8.5V
7.61
100
8.1
8.5
V
w.r.t. SRC
Sourcing 100mA to GATE
VGATE-LOW
Gate Driver Output Low
180
290
mV
tRISE
VGATE Rise Time
CGATE = 1nF across GATE and SRC
CGATE = 1nF across GATE and SRC
CGATE = 1nF across GATE and SRC
CGATE = 1nF across GATE and SRC
22
14
68
84
ns
ns
ns
ns
tFALL
VGATE Fall Time
tRISE-PG-DELAY
tFALL-PG-DELAY
VGATE Low to High Propagation Delay
VGATE High to Low Propagation Delay
CURRENT SOURCE AT ADJ PIN
IADJ-STARTUP
IADJ-ELEC-XFR
IADJ-MAG-XFR
Output Current of ADJ pin at Startup
VADJ = 0V
16
8
20
11.5
9.5
24
15
12
µA
µA
µA
Output Current of ADJ pin for Electronic
Transformers
An Electronic Transformer is Detected
Output Current of ADJ pin for Inductive An Magnetic Transformer is Detected
Transformers
7
CURRENT SENSE COMPARATOR
VSEN-UPPER-TH VSEN Upper Threshold Over VADJ
VSEN-LOWER-TH
VSEN-VADJ, VADJ=0.2V, VGATE at falling
edge
8.9
14.9
20.9
–8.8
mV
mV
VSEN-VADJ, VADJ=0.2V VGATE at rising
edge
VSEN Lower Threshold Over VADJ
–20.6 –14.9
VSEN-HYS
VSEN Hysteresis
(VSEN-UPPER-TH - VSEN-LOWER-TH
)
22.5
–3.5
29.8
0.02
37.5
3.5
mV
mV
VSEN-OFFSET
VSEN Offset w.r.t. VADJ
(VSEN-UPPER-TH + VSEN-LOWER-TH)/2
ACTIVE low-side input rectifiers
RACn-ON In resistance of AC1 and AC2 to GND
IACn = 200mA
300
570
mΩ
(1) VCC provides self bias for the internal gate drive and control circuits. Device thermal limitations limit external loading.
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ELECTRICAL CHARACTERISTICS (continued)
Specification with standard type are for TA=TJ= 25°C only; limits in boldface type apply over the full Operating Junction
Temperature (TJ) range. Minimum and Maximum are specified through test, design or statistical correlation. Typical values
represent the most likely parametric norm at TJ= 25°C, and are provided for reference purposes only. Unless otherwise stated
the following conditions apply: VVP = 12V
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
Turn ON Voltage Threshold of AC1 and
AC2
VACn-ON-TH
VACn-OFF-TH
VACn Decreasing
36
52
67
mV
Turn OFF Voltage Threshold of AC1
and AC2
VACn Increasing
77
90
104
mV
VACn-TH-HYS
IACn-OFF
Hysteresis Voltage of AC1 and AC2
Off Current of AC1 and AC2
VACn-OFF-TH - VACn-ON-TH
VACn = 45V
39
21
mV
µA
32
OUTPUT OVER-VOLTAGE-PROTECTION (OVP)
Output Over-Voltage-Detection Upper
VADJ-OVP-UPTH
Threshold
VADJ Increasing, VGATE at falling edge
VADJ Decreasing, VGATE at rising edge
VADJ-OVP-UPTH - VADJ-OVP-LOTH
0.353 0.384 0.415
0.312 0.339 0.366
V
V
Output Over-Voltage-Detection Lower
VADJ-OVP-LOTH
Threshold
Output Over-Voltage-Detection
VADJ-OVP-HYS
Hysteresis
25
46
67
mV
THERMAL SHUTDOWN
TSD
Thermal Shutdown Temperature
TJ Rising
TJ Falling
165
30
°C
°C
Thermal Shutdown Temperature
Hysteresis
TSD-HYS
6
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SNVS900A –DECEMBER 2012–REVISED JANUARY 2013
TYPICAL CHARACTERISTICS
All curves taken for the boost circuit are with 500mA nominal input current and 6 serial LEDs. All curves taken for the SEPIC
circuit are with 500mA nominal input current and 3 serial LEDs.TA = –40°C to 125°C, unless otherwise specified.
Operation Current vs. Temperature
VCC vs. Temperature (ICC = 0mA)
1.6
1.5
1.4
1.3
1.2
1.1
1
8.45
8.4
VVP=42V
VVP=42V
8.35
8.3
VVP=12V
VVP=6.5V
VVP=12V
8.25
8.2
8.15
-40
-20
0
20
40
60
80
100 120 140
-40
-20
0
20
40
60
80
100 120 140
C001
C002
Ambient Temperature, TA (°C)
Ambient Temperature, TA (°C)
Figure 1.
Figure 2.
VCC UVLO Rising Threshold vs. Temperature
VVP=12V, GATE='Hi'
VCC UVLO Falling Threshold vs. Temperature
VVP=12V, GATE='Low'
5.42
5.4
5.02
5
5.38
5.36
5.34
5.32
5.3
4.98
4.96
4.94
4.92
-40
-20
0
20
40
60
80
100 120 140
-40
-20
0
20
40
60
80
100 120 140
C003
C004
Ambient Temperature, TA (°C)
Ambient Temperature, TA (°C)
Figure 3.
Figure 4.
ACn Turn OFF Threshold vs. Temperature
ACn Turn ON Threshold vs. Temperature
140
120
100
80
80
70
60
50
40
30
60
40
-40
-20
0
20
40
60
80
100 120 140
-40
-20
0
20
40
60
80
100 120 140
C005
C006
Temperature, TA (°C)
Ambient Temperature, TA (°C)
Figure 5.
Figure 6.
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TYPICAL CHARACTERISTICS (continued)
All curves taken for the boost circuit are with 500mA nominal input current and 6 serial LEDs. All curves taken for the SEPIC
circuit are with 500mA nominal input current and 3 serial LEDs.TA = –40°C to 125°C, unless otherwise specified.
Output Current (BOOST) vs. Temperature
Output Current (SEPIC) vs. Temperature
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
VIN=12V
VIN=12V
-40
-40
-40
-20
0
20
40
60
80
100 120 140
-40
-40
-40
-20
0
20
40
60
80
100 120 140
C007
C008
Ambient Temperature, TA (°C)
Ambient Temperature, TA (°C)
Figure 7.
Figure 8.
Output Power (BOOST) vs. Temperature
Output Power (SEPIC) vs. Temperature
12
10
8
10
8
6
VIN=12V
VIN=12V
6
4
4
2
2
0
0
-20
0
20
40
60
80
100 120 140
-20
0
20
40
60
80
100 120 140
C009
C010
Ambient Temperature, TA (°C)
Ambient Temperature, TA (°C)
Figure 9.
Figure 10.
Efficiency (BOOST) vs. Temperature
Efficiency (SEPIC) vs. Temperature
100
90
80
70
60
50
100
90
80
70
60
50
VIN=18V
VIN=15V
VIN=18V
VIN=15V
VIN=12V
VIN=12V
VIN=9V
VIN=6V
VIN=9V
VIN=6V
-20
0
20
40
60
80
100 120 140
-20
0
20
40
60
80
100 120 140
C011
C012
Ambient Temperature, TA (°C)
Ambient Temperature, TA (°C)
Figure 11.
Figure 12.
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SNVS900A –DECEMBER 2012–REVISED JANUARY 2013
OVERVIEW
The TPS92560 is a simple hysteretic control switching LED driver for MR16 or AR111 lighting applications. The
device accepts DC voltage, AC voltage and electronic transformer as an input power source. The compact
application circuit can fit into a generic case of MR16 lamps easily. The hysteretic inductor current control
scheme requires no small signal control loop compensation and maintains constant average input current to
secure high compatibility to different kinds of input power source. The TPS92560 can be configured to either a
step-up or step-up/down LED driver for the use of different number of LEDs. The patent pending current control
mechanism allows the use of a single set of component and PCB layout for serving different output power
requirements by changing the number of LEDs. The integrating of the active low-side input rectifiers reduces the
power loss for voltage rectification and saves two external diodes of a generic bridge rectifier to aim for a simple
end application circuit. When the driver is used with an AC voltage source or electronic transformer, the current
regulation level increases accordingly to maintain an output current close to the level that when it is used with a
DC voltage source. With the output over-voltage protection and over-temperature shutdown functions, the
TPS92560 is specifically suitable for the applications that are space limited and need wide acceptance to
different power sources.
VCC REGULATOR
The VCC pin is the output of the internal linear regulator for providing an 8.45V typical supply voltage to the
MOSFET driver and internal circuits. The output current of the VCC pin is limited to 30mA typical. A low ESR
ceramic capacitor of 0.47μF or higher capacitance should be connected across the VCC and SRC pins to supply
transient current to the MOSFET driver.
MOSFET DRIVER
The GATE pin is the output of the gate driver which referenced to the SRC pin. The gate driver is powered
directly by the VCC regulator which the maximum gate driving current is limited to 30mA typical. To prevent
hitting the VCC current limit, it is suggested to use a low gate charge MOSFET when high switching frequency is
needed.
THE ADJ PIN
The voltage on the ADJ pin determines the reference voltage for the input current regulation. Typically, the ADJ
pin voltage is divided from the output voltage of the circuit by a voltage divider, thus the average input current is
adjusted with respect to the number of LEDs used. The voltage of the ADJ pin determines the input current
following the expression:
VVP
RSEN
RADJ2
RADJ1 + RADJ2
x
IIN(nom)
=
(1)
Output Over-Voltage-Protection
In the TPS92560, a function of output Over-Voltage Protection (OVP) is provided to prevent damaging of the
circuit due to an open circuit of the LED. The OVP function is implemented to the ADJ pin. When the voltage of
the ADJ pin exceeds 0.384V typical, the OVP circuit disables the MOSFET driver and turns off the main switch to
allow the output capacitor to discharge. As the voltage of the ADJ pin decreases to below 0.353V typical, the
MOSFET driver is enabled and the TPS92560 returns to normal operation. The triggering threshold of the output
voltage is determined by the value of the resistors RADJ1 and RADJ2, which can be calculated using the following
equation:
RADJ2
RADJ1 + RADJ2
VVP
x
≤ 0.384V
(2)
When defining the OVP threshold voltage, it is necessary to certain that the OVP threshold voltage does not
exceed the rated voltage of the output rectifier and capacitor to avoid damaging of the circuit.
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THE AC1 AND AC2 PINS
The TPS92560 provides two internal active rectifiers for input voltage rectification. Each internal rectifier connects
across the ACn pin to GND. These internal active rectifiers function as the low-side diode rectifiers of a generic
bridge rectifier. The integrating of the active rectifiers helps in saving two external diodes of a bridge rectifier
along with an improvement of power efficiency. For high power applications, for instance, 12W output power,
external diode rectifiers can be added across the ACn pin to GND to reduce heat dissipation on the TPS92560.
DETECTION OF POWER SOURCE
VIN (From elect. transformer)
12V × 2
Time
0
Switching period
Dead time
of the elect. transformer
1/50Hz or 1/60Hz
Figure 13. The inherent dead time of the output voltage of an electronic transformer
Both the voltages of a generic AC source (50/60Hz) and an electronic transformer carry certain amount of dead
time inherently, as shown in Figure 13. The existing of the dead time leads to a drop of the RMS input power to
the driver circuit. In order to compensate the drop of the RMS input power, the ADJ pin sources current to the
resistor, RADJ2 to increase the reference voltage for the current regulation loop and in turn increase the RMS
input power accordingly when an AC voltage source or electronic transformer is detected. The output current of
the ADJ pin for an AC input voltage and electronic transformer are 9.5μA and 11.5μA typical respectively.
Practically the amount of the power for compensating the dead time of the input power source differs case to
case depending on the characteristics of the power source, the value of the RADJ1 and RADJ2 might need a fine
adjustment in accordance to the characteristics of the power source. The additional output power for
compensating the dead time of the power sources (ΔPLED) are calculated using the following equations:
For 50/60Hz AC power source:
RADJ2 ´ 9.5 mA
DP
= V ´
´ h
LED-50/60 Hz
IN
RSEN
(3)
(4)
For electronic transformer:
RADJ2 ´11.5 mA
DP
= V ´
´ h
LED-ELECT-XFR
IN
RSEN
CURRENT REGULATION
In the TPS92560, the input current regulation is attained by limiting the peak and valley of the inductor current.
Practically the inductor current sensing is facilitated by detecting the voltage on the resistor, RSEN. Because the
current flows through the RSEN is a sum total of the currents of the main switch and LEDs, the voltage drop on
the RSEN reflects the current of the inductor that is identical to the input current to the LED driver circuit.
Figure 14 shows the waveform of the inductor current ripple with the peak and valley values controlled.
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SNVS900A –DECEMBER 2012–REVISED JANUARY 2013
IL
tON
tOFF
Switch off
IL(peak)
VSEN-UPPER-TH
RSEN
Time
VSEN-LOWER-TH
RSEN
Switch on
IL(valley)
tFALL-PG-DELAY tRISE-PG-DELAY
SVA-30207404
Figure 14. Inductor Current Ripple in Steady State
The voltage of the ADJ pin is determined by the forward voltage of the LED and divided from the VVP by a
resistor divider. The equation for calculating the VADJ as shown in the following expression:
RADJ2
VADJ = VVP
´
RADJ1 + RADJ2
(5)
In steady state, the voltage drop on the RADJ1 is identical to the forward voltage of the LED (VLED) and the voltage
across the RADJ2 is identical to the voltage across the RSEN. The LED current, ILED is then calculated following the
equations:
In steady state:
VLED = VRADJ1
VSEN = VRADJ2
VSEN
(6)
(7)
IIN(nom)
=
RSEN
(8)
(9)
Since
PLED = PIN x η
where η is the conversion efficiency
Thus,
VLED x ILED = VIN x IIN(nom) x η
(10)
Put the expressions (2) to (4) into (5):
IADJ2 x RADJ2
ILED = VIN
x
x η
IADJ1 x RADJ1 x RSEN
(11)
Due to the high input impedance of the ADJ pin, the current flows into the ADJ pin can be neglected and thus
IRADJ1 equals IRADJ2. The LED current is then calculated following the expressions below:
RADJ2
x η
ILED = VIN
x
RADJ1 x RSEN
(12)
Practically, the conversion efficiency of a boost circuit is almost a constant around 85%. Being assumed that the
efficiency term in the ILED expression is a constant, the LED current depends solely on the magnitude of the input
voltage, VIN. Without changing a component, the output power of the typical application circuits of the TPS92560
is adjustable by using different number of LEDs.
The output power is calculated by following the expression:
RADJ2
PLED = VLED x VIN
x
x η
RADJ1 x RSEN
(13)
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SWITCHING FREQUENCY (Boost Configuration)
In the following sections, the equations and calculations are limited to the boost configuration only (i.e. the LED
forward voltage higher than the input voltage), unless otherwise specified. The application information for the
SEPIC and other circuit topologies are available in separate application notes and reference designs. In the
boost configuration, including the propagation delay of the control circuit, the ON and OFF times of the main
switch are calculated following the expressions:
VSEN-UPPER-TH x L
tON
=
+ tFALL-PG-DELAY x 2
RSEN x [VIN - VD - IIN(nom) x (RL + RDS(ON) +RSEN + RAC-FET)]
(14)
VSEN-LOWER-TH x L
tOFF
=
+ tRISE-PG-DELAY x 2
RSEN x [VLED - VIN - 2VD - IIN(nom) x (RL +RSEN + RAC-FET)]
(15)
In the above equations, the VD is the forward voltage of D3, RL is the DC resistance of L1, RDS(ON) is the ON
resistance of Q1 and RAC-FET is the turn ON resistance of the internal active rectifier with respect to the typical
application circuit diagram.
Practically the resistance of the RL, RDS(on) and RAC-FET is in the order if serveral tenth of mΩ, by assuming a 0.5V
diode forward voltage and the sum total of the RL, RDS(ON) and RAC-FET is close to 1Ω, the on and off times of Q1
can be approximated using the following equations:
14.9mV x L
tON
≈
+ 84ns x 2
RSEN x [VIN – 0.5V - IIN(nom) x (1 + RSEN)]
(16)
14.9mV x L
tOFF
≈
+ 68ns x 2
RSEN x [VLED - VIN - 1V - IIN(nom) x (1 + RSEN)]
(17)
With the switching on and OF times determined, the switching frequency can be calculated using the following
equation:
1
fSW
=
t
ON + tOFF
(18)
Because of the using of hysteretic control scheme, the switching frequency of the TPS92560 in steady state is
dependent on the input voltage, output voltage and inductance of the inductor. Generally a 1 MHz to 1.5 MHz
switching frequency is suggested for applications using an electronic transformer as the power source.
INDUCTOR SELECTION (Boost Configuration)
Because of the using of the hysteretic control scheme, the switching frequency of the TPS92560 in a boost
configuration can be adjusted in accordance to the value of the inductor being used. Derived from the equations
(12) and (13), the value of the inductor can be determined base on the desired switching frequence by using the
following equation:
1
− 304ns ×RSEN
fSW
L =
1
1
+
× 29.8mV
V
IN − 0.5V −IIN(nom) ×(1+ RSEN
)
VLED − VIN −1V −IIN(nom) ×(1+ RSEN )
(19)
When selecting the inductor, it is essential to ensure the peak inductor current does not exceed the the factory
suggested saturation current of the inductor. The values of the peak and valley inductor current are calculated
using the following equations:
Peak inductor current:
[VIN - VD - IIN(nom) x (RL + RDS(ON) +RSEN + RAC-FET)] x tON
IL(peak)
=
+ IIN(nom)
(20)
Valley inductor current:
12
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SNVS900A –DECEMBER 2012–REVISED JANUARY 2013
[VLED - VIN - 2VD - IIN(nom) x (RL +RSEN + RAC-FET)] x tOFF
IL(valley) = IIN(nom)
-
(21)
Assume the total resistance of the RL, RDS(on) and RAC-FET is 1Ω and the diode drop, VD equal to 1V, the peak
and valley currents of the inductor can be approximated using the following equations:
[VIN – 0.5V - IIN(nom) x (1 + RSEN)] x tON
IL(peak)
≈
+ IIN(nom)
(22)
(23)
[VLED - VIN - 1V - IIN(nom) x (1 + RSEN)] x tOFF
IL(valley) ≈ IIN(nom)
-
In order not to saturate the inductor, an inductor with a factory guranteed saturation current (ISAT) 20% higher
than the IL(peak) is suggested. Thus the ISAT of the inductor should fulfill the following requirement:
ISAT ≥ IL(peak) x 1.2
(24)
THERMAL SHUTDOWN
The TPS92560 includes a thermal shutdown circuitry that ceases the operation of the device to avoid permanent
damage. The threshold for thermal shutdown is 165°C with a 30°C hysteresis typical. During thermal shutdown
the VCC regulator is disabled and the MOSFET is turned off.
INPUT SURGE VOLTAGE PROTECTION
When use with an electronic transformer, the surge voltage across the input terminals can be sufficiently high to
damage the TPS92560 depending on the charactistics of the electronic transformer. To against potential
damaging due to the input surge voltage, a 36V zener diode can be connected across the input bridge rectifier as
shown in Figure 15.
L1
CIN
36V
Zener
Diode
D1
D2
R1
U1
TPS92560
AC1
PGND
AC2
Power
Source
Figure 15. Input surge voltage protection using an external zener diode
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EXAMPLE APPLICATION CIRCUITS
In the applications that need true regulation of the LED current, the intrinsic input current control loop can be
changed to monitor the LED current by adding an external LED current sensing circuit. Figure 16 and Figure 19
show the example circuits for true LED current regulation in boost and SEPIC configurations respectively. In the
circuits, the U3 (TL431) maintains a constant 2.5V voltage drop on the resistors, R3 and R7. Because the U2
(TL431) maintains a constant voltage drop on the R3, the power dissipation on the output current sensing
resistor, R7 can be minimized by setting a low voltage drop on the R7. Because the change of the current flowing
through the R7 reflects in the change of the cathode current of U3 and eventually adjusts the ADJ pin voltage of
the TPS92560, the LED current is regulated independent of the change of the input voltage.
Boost Application Circuit with LED Current Regulation
The specifications of the boost application circuit in Figure 16 are as listed below:
•
•
•
•
Objective input voltage: 3VDC to 18VDC / 12VAC(50Hz or 60Hz) / Generic MR16 electronic transformer
LED forward voltage: 20VDC typical
Output current: 300mA typical (@12VDC input)
Output power: 6W typical (@12VDC input)
L1
D3
15µH
2A 40V
LED
CIN
25V
1µF
Z1
VCC
R2
R5
15k
36V
COUT1
35V
330µF
COUT
1µF
4.02k
R1
105
D1
D2
VCC
2A 40V
2A 40V
Q1
3A 60V
R4
562
TPS92560
R6
40.2k
U2
U3
TL431
GATE
AC1
Power
Source
TL431
SRC
VCC
SEN
GND
PGND
AC2
VP
C1
1µF
R3
4.02k
CVCC
1µF
R7
1
RADJ2
1k
CADJ
4.7µF
CVP
47nF
ADJ
RSEN
0.2
U1
Figure 16. Using the TPS92560 in SEPIC configuration with LED current regulation
Typical Characteristics of the Boost Example Circuit in Figure 16
All curves taken at VIN = 3V to 18VDC in boost configuration, with 300mA nominal output current, 6 serial LEDs.
TA = 25°C.
LED Current vs. Input Voltage
Efficiency vs. Input Voltage
350
300
250
200
150
100
50
100
90
80
70
60
50
40
30
0
2
4
6
8
10
12
14
16
18
20
0
2
4
6
8
10
12
14
16
18
20
C017
C018
Input Voltage, VIN (V)
Input Voltage, VIN (V)
Figure 17.
Figure 18.
14
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SNVS900A –DECEMBER 2012–REVISED JANUARY 2013
SEPIC Application Circuit with LED Current Regulation
The specifications of the SEPIC application circuit in Figure 16 are as listed below:
•
•
•
•
Objective input voltage: 3VDC to 18VDC / 12VAC(50Hz or 60Hz) / Generic MR16 electronic transformer
LED forward voltage: 13VDC typical
Output current: 300mA typical (@12VDC input)
Output power: 4W typical (@12VDC input)
C2
L1
D3
15µH
1µF
2A 40V
LED
CIN
25V
1µF
Z1
VCC
R2
R5
1.82k
36V
COUT1
25V
330µF
COUT
4.7µF
4.02k
L2
15µH
R1
105
D1
D2
VCC
2A 40V
2A 40V
Q1
3A 60V
R4
562
TPS92560
R6
36.5k
U2
U3
TL431
GATE
AC1
Power
Source
TL431
SRC
VCC
SEN
GND
PGND
AC2
VP
C1
1µF
R3
4.02k
CVCC
1µF
R7
1
RADJ2
1k
CADJ
4.7µF
CVP
100nF
ADJ
RSEN
0.3
U1
D4
600mA 40V
Figure 19. Using the TPS92560 in SEPIC configuration with LED current regulation
Typical Characteristics of the SEPIC Example Circuit in Figure 19
All curves taken at VIN = 3V to 18VDC in SEPIC configuration, with 300mA nominal output current, 4 serial LEDs.
TA = 25°C.
LED Current vs. Input Voltage
Efficiency vs. Input Voltage
350
300
250
200
150
100
50
100
90
80
70
60
50
40
30
0
2
4
6
8
10
12
14
16
18
20
0
2
4
6
8
10
12
14
16
18
20
C019
C020
Input Voltage, VIN (V)
Input Voltage, VIN (V)
Figure 20.
Figure 21.
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PACKAGE OPTION ADDENDUM
www.ti.com
24-Jan-2013
PACKAGING INFORMATION
Orderable Device
TPS92560DGQ/NOPB
TPS92560DGQR/NOPB
Status Package Type Package Pins Package Qty
Eco Plan Lead/Ball Finish
MSL Peak Temp
Op Temp (°C)
-40 to 85
Top-Side Markings
Samples
Drawing
(1)
(2)
(3)
(4)
ACTIVE
MSOP-
PowerPAD
DGQ
10
10
1000
3500
Green (RoHS
& no Sb/Br)
CU SN
CU SN
Level-3-260C-168 HR
SN3B
SN3B
ACTIVE
MSOP-
DGQ
Green (RoHS
& no Sb/Br)
Level-3-260C-168 HR
-40 to 85
PowerPAD
(1) The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability
information and additional product content details.
TBD: The Pb-Free/Green conversion plan has not been defined.
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that
lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between
the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above.
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight
in homogeneous material)
(3) MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.
(4) Only one of markings shown within the brackets will appear on the physical device.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information
provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and
continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.
TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.
Addendum-Page 1
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