ZLED7015 [IDT]
1.0MHz Boost Converter;
| 型号： | ZLED7015 |
| 厂家： | 
INTEGRATED DEVICE TECHNOLOGY |
| 描述： | 1.0MHz Boost Converter |
| 文件： | 总22页 (文件大小：522K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
ZLED7015
1.0MHz Boost Converter
with Internal 35V Switch
Datasheet
Brief Description
Features
• Integrated 35V power switch
• Wide input range: 6VDC to 30VDC
• Over-temperature protection
The ZLED7015, one of our ZLED family of LED
control ICs, is a constant current boost converter
with an internal high-power 35V switch. It is opti-
mal for driving multiple white LEDs connected in
series so that the LED current is uniform for better
brightness and color control. It can also drive
devices that require a constant voltage and is
capable of operating efficiently with voltage
supplies ranging from 6VDC to 30VDC. It is ideal
for diverse lighting applications requiring low sup-
ply voltages such as SELV applications. Typically,
smaller, less expensive external components can
be used since the ZLED7015 switches at 1.0MHz
(typical).
• Over-voltage (open LED string) protection adjusted
via external resistor divider
• Under-voltage lockout ensures reliable circuit
operation
• Control of output current during start-up via internal
“soft-start”
• Switching frequency: 1.0MHz
• Single pin on/off or brightness control via PWM,
microcontroller, or DC voltage control signal input
• MSOP-10 package
The ZLED7015 output current is adjustable via an
external current sense resistor RS connected from
the FB pin to ground.
Benefits
• High efficiency: up to 95% efficiency
• Few small, low-profile components needed for
operation
The ZLED7015 improves efficiency and minimizes
power losses in the current setting resistor RS by
use of an internal 0.3V feedback reference vol-
tage.
• Small form-factor package
Available Support
Dimming can be controlled using a pulse-width
modulation (PWM) waveform or a DC voltage
applied to the FB pin.
• Evaluation Kit
Physical Characteristics
The ZLED7015 provides a “soft-start” function to
prevent excessive in-rush current on start-up and
ensures a controlled rise of the output voltage.
• Operating temperature: -40°C to 85°C
• RoHS-compliant
Over-voltage protection is adjustable via external
resistors R1 and R2.
ZLED7015 Typical Application Circuit
VIN = 6 to 30 VDC
VOUT
L1
D1
REN
R1
CIN
LED
String
C2
EN
LX
RVDD
C1
VDD
OVP
R2
COVP
COUT
FB
VP
CVDD
ZLED7015
AGND
PGND
CVP
RS
© 2016 Integrated Device Technology, Inc.
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ZLED7015
1.0MHz Boost Converter
with Internal 35V Switch
Datasheet
ZLED7015 Block Diagram
6 to 30 VDC
VIN
L1
D1
RVDD
ZLED7015
9
2
LDO
REN
C2
VP
VDD
CVDD
CIN
C1
COUT
Bias & Reference
Bandgap
CVP
7
–
10
FB
R
+
LX
R1
RS
VREF
n LED
S
Q
Oscillator
Ramp Gen
COVP
R2
∑
Slope Compensation
4
Shutdown
RS
EN
Current Sense
OVP
Over-Voltage
Protection
Thermal
Protection
Current
Limit
6
1
3, 5
PGND
AGND
Typical Applications
Low-Voltage Retro-fit Lighting
MR16 Lights
Architectural/Building Lighting
Replacement Tubes
LED Backlighting
SELV Lighting
Signage and Outdoor Lighting
General Purpose Low-Voltage Industrial and Consumer Applications
Ordering Information
Product Sales Code
Description
Package
ZLED7015ZI1R
ZLED7015 – 1.0MHz Boost Converter with Internal 35V Switch
ZLED7015-E1 Evaluation Board, 1 ZLED-PCB10, and 5 ZLED7015 ICs
MSOP-10 (Tape & Reel)
Kit
ZLED7015KIT-E1
Corporate Headquarters
6024 Silver Creek Valley Road
San Jose, CA 95138
Sales
Tech Support
www.IDT.com/go/support
1-800-345-7015 or 408-284-8200
Fax: 408-284-2775
www.IDT.com/go/sales
www.IDT.com
DISCLAIMER Integrated Device Technology, Inc. (IDT) reserves the right to modify the products and/or specifications described herein at any time, without notice, at IDT's sole discretion. Performance
specifications and operating parameters of the described products are determined in an independent state and are not guaranteed to perform the same way when installed in customer products. The
information contained herein is provided without representation or warranty of any kind, whether express or implied, including, but not limited to, the suitability of IDT's products for any particular purpose, an
implied warranty of merchantability, or non-infringement of the intellectual property rights of others. This document is presented only as a guide and does not convey any license under intellectual property
rights of IDT or any third parties.
IDT's products are not intended for use in applications involving extreme environmental conditions or in life support systems or similar devices where the failure or malfunction of an IDT product can be
reasonably expected to significantly affect the health or safety of users. Anyone using an IDT product in such a manner does so at their own risk, absent an express, written agreement by IDT.
Integrated Device Technology, IDT and the IDT logo are trademarks or registered trademarks of IDT and its subsidiaries in the United States and other countries. Other trademarks used herein are the
property of IDT or their respective third party owners. For datasheet type definitions and a glossary of common terms, visit www.idt.com/go/glossary. All contents of this document are copyright of Integrated
Device Technology, Inc. All rights reserved.
© 2016 Integrated Device Technology, Inc.
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ZLED7015 Datasheet
Contents
1
IC Characteristics.......................................................................................................................................................... 5
1.1
Absolute Maximum Ratings ................................................................................................................................... 5
Operating Conditions............................................................................................................................................. 5
Electrical Parameters............................................................................................................................................. 6
Typical Operating Characteristics.......................................................................................................................... 7
Characteristic Waveforms.................................................................................................................................... 10
1.2
1.3
1.4
1.5
2
Circuit Description....................................................................................................................................................... 12
2.1
2.2
2.2.1
EN Pin, VP Pin, and Soft-Start Function.............................................................................................................. 12
Output Current Control......................................................................................................................................... 12
Output Current and RS.................................................................................................................................. 12
Dimming via External DC Voltage Control.................................................................................................... 13
Dimming via PWM Control............................................................................................................................ 14
Microcontroller LED Control.......................................................................................................................... 15
Constant Voltage Application........................................................................................................................ 15
2.2.2
2.2.3
2.2.4
2.2.5
3
4
Application Circuit Design ........................................................................................................................................... 17
3.1
External Component – RS .................................................................................................................................... 17
External Component – Inductor L1....................................................................................................................... 17
External Components – Input Decoupling Capacitors C1 and CIN........................................................................ 17
External Component –Output Capacitors C2 and COUT........................................................................................ 17
External Component – Diode D1.......................................................................................................................... 17
Additional External Components.......................................................................................................................... 17
3.2
3.3
3.4
3.5
3.6
Operating Conditions................................................................................................................................................... 18
4.1
Under-Voltage Lockout........................................................................................................................................ 18
Over-Voltage Threshold and Open-Circuit Protection.......................................................................................... 18
Over-Temperature Protection .............................................................................................................................. 18
4.2
4.3
5
6
7
ESD/Latch-Up-Protection............................................................................................................................................ 19
Pin Configuration and Package................................................................................................................................... 19
Layout Requirements.................................................................................................................................................. 21
7.1
General Considerations and Ground Traces ....................................................................................................... 21
Layout Considerations for C1, CIN, C2 and COUT................................................................................................... 21
Layout Considerations for the EN Pin.................................................................................................................. 21
Layout Considerations for the LX Pin, L1 External Coil, and D1 Diode................................................................. 21
Layout Considerations for the External Current Sense Resistor (RS) .................................................................. 21
Layout Considerations for CVP and CVDD.............................................................................................................. 21
Layout Considerations for the Thermal Pad......................................................................................................... 21
7.2
7.3
7.4
7.5
7.6
7.7
8
9
Glossary of Terms....................................................................................................................................................... 22
Ordering Information ................................................................................................................................................... 22
10 Document Revision History......................................................................................................................................... 22
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ZLED7015 Datasheet
List of Figures
Figure 1.1
Figure 1.2
Figure 1.3
Figure 1.4
Figure 1.5
Figure 1.6
Figure 1.7
Figure 1.8
Figure 1.9
IOUT vs. VIN with RS = 0.42Ω............................................................................................................................ 7
IOUT vs. VIN with RS = 0.88Ω............................................................................................................................ 7
IOUT vs. VOUT with RS = 0.42Ω......................................................................................................................... 7
IOUT vs. VOUT with RS = 0.88Ω......................................................................................................................... 7
Efficiency vs. VIN with RS = 0.42Ω .................................................................................................................. 8
Efficiency vs. VIN with RS = 0.88Ω .................................................................................................................. 8
Efficiency vs. VOUT with RS = 0.42Ω................................................................................................................ 9
Efficiency vs. VOUT with RS = 0.88Ω................................................................................................................ 9
VFB Reverence Voltage vs. VIN ....................................................................................................................... 9
Figure 1.10 IOUT vs. PWM Duty Cycle................................................................................................................................ 9
Figure 1.11 VOUT, VIN, and IL1 during Soft Start................................................................................................................ 10
Figure 1.12 VOUT, VLX, and IOUT during Typical Operation................................................................................................ 11
Figure 1.13 VOUT, VLX, and IL1 when Over-Voltage Protection (OVP) Threshold is Exceeded......................................... 11
Figure 2.1
Figure 2.2
Figure 2.3
Figure 2.4
Figure 6.1
Figure 6.2
Typical Application Circuit ............................................................................................................................ 13
Example Circuit for Controlling Output Current via an External DC Control Voltage.................................... 13
Example Circuit for Controlling Output Current via a PWM Control Signal................................................... 14
Example Circuit for Constant Voltage Source Applications.......................................................................... 16
ZLED7015 Pin Configuration—MSOP-10 Package...................................................................................... 19
MSOP-10 Package Dimensions for the ZLED7015...................................................................................... 20
List of Tables
Table 1.1
Table 1.2
Table 1.3
Table 6.1
Absolute Maximum Ratings............................................................................................................................ 5
Operating Conditions...................................................................................................................................... 5
Electrical Parameters ..................................................................................................................................... 6
Pin Description MSOP-10............................................................................................................................. 19
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ZLED7015 Datasheet
1
IC Characteristics
Note: Exceeding the maximum ratings given in this section could cause operation failure and/or cause permanent
damage to the ZLED7015. Exposure to these conditions for extended periods may affect device reliability.
1.1
Absolute Maximum Ratings
Table 1.1
No.
Absolute Maximum Ratings
PARAMETER
SYMBOL
VDD
CONDITIONS
MIN
TYP
MAX
UNIT
1.1.1
Supply voltage on VDD pin
(also see specification
1.2.2)
-0.3
40.0
V
1.1.2
1.1.3
1.1.4
LX pin output voltage
All other pins
VLX
-0.3
-0.3
40.0
6.0
V
V
ESD Performance
Human Body Model
High voltage pins:
1, 4, 5, 9, and 10
±2.5
kV
Low voltage pins:
2, 3, 6, 7, and 8
±4
kV
1.1.5
1.1.6
1.1.7
1.1.8
Junction temperature
Storage temperature
Tj MAX
TST
-40
-65
150
150
260
60
°C
°C
Lead soldering temperature
10 seconds maximum
°C
Junction-to-ambient
thermal resistance
RθJA
°C/W
1.2
Operating Conditions
Table 1.2
No.
Operating Conditions
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNIT
1.2.1
Operating temperature
TOP
-40
+85
°C
Supply voltage on VDD pin
(also see absolute maxi-
mum specification 1.1.1)
1.2.2
VDD
6
30
V
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ZLED7015 Datasheet
1.3
Electrical Parameters
Test conditions for the following specifications are Tamb = 25°C (typical) and VDD = 12V, unless otherwise noted.
Production testing of the ZLED7015 is performed at 25°C unless otherwise stated. Functional operation of the
ZLED7015 and specified parameters at other temperatures are guaranteed by design, characterization, and
process control.
Table 1.3
Electrical Parameters
No.
PARAMETER
SYMBOL
CONDITIONS
Continuous switching
Quiescent: no switching
MIN
TYP
2
MAX
UNIT
mA
1.3.1
1.3.2
Supply current
IDD
1.1
mA
Shutdown: no switching;
VEN=0V
Shutdown current
ISD
15
µA
1.3.3
1.3.4
1.3.5
LX switching frequency
Maximum duty cycle
fOCS
DLX
1
MHz
%
90
EN pin ON threshold voltage
VENon
Rising VEN
Falling VEN
1.4
V
EN pin OFF threshold
voltage
1.3.6
1.3.7
1.3.8
1.3.9
VENoff
VFB
RDSon
ISWlimit
ISWleak
VP
0.4
0.315
1.2
V
V
Ω
A
Internal feedback reference
voltage
0.285
0.3
0.8
2.1
Integrated switch ON
resistance
Integrated switch current
limit
Duty cycle = 90%
1.8
4.5
2.4
Integrated switch leakage
current
1.3.10
1.3.11
1.3.12
1.3.13
1.3.14
1.3.15
1.3.16
VLX = 40V
1
µA
V
Internal regulator
6V<VDD<30V, CVP=10μF
5.0
150
50
5.5
Over-temperature protection
(OTP) threshold
TOTP
°C
°C
V
OTP threshold hysteresis
TOTP_HYS
VUVLO
VUVLO_HYS
VOVP_TH
Under-voltage lock-out
threshold (UVLO)
Falling VDD
2.9
100
0.9
UVLO hysteresis
mV
V
Internal over-voltage
threshold reference voltage
Over-voltage protection
threshold hysteresis
1.3.17
VOVP_TH_HYS
10
mV
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ZLED7015 Datasheet
1.4
Typical Operating Characteristics
The curves are valid for the typical application circuit and Tamb = 25°C unless otherwise noted.
Figure 1.1
IOUT vs. VIN with RS = 0.42Ω
Figure 1.2
IOUT vs. VIN with RS = 0.88Ω
730
360
355
350
345
340
335
720
710
700
690
680
VOUT=30V,RS=0.88Ω,L1=10µH
VOUT=30V,RS=0.42Ω,L1=10µH
330
670
18
10
15
20
25
30
20
22
24
26
28
VIN (V)
VIN (V)
Figure 1.3
IOUT vs. VOUT with RS = 0.42Ω
Figure 1.4
IOUT vs. VOUT with RS = 0.88Ω
730
360
720
710
700
690
680
355
350
345
340
335
VIN=12V,RS=0.88Ω,L1=10µH
VIN=24V,RS=0.42Ω,L1=10µH
330
670
25
12
15
18
21
24
27
30
26
27
28
29
30
VOUT (V)
VOUT (V)
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ZLED7015 Datasheet
Figure 1.5
Efficiency vs. VIN with RS = 0.42Ω
Figure 1.6
Efficiency vs. VIN with RS = 0.88Ω
100
100
90
80
70
60
90
80
70
60
VOUT=30V,RS=0.88Ω,L1=10µH
VOUT=30V,RS=0.42Ω,L1=10µH
50
50
18
10
15
20
25
30
20
22
24
26
28
VIN (V)
VIN (V)
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ZLED7015 Datasheet
Figure 1.7
Efficiency vs. VOUT with RS = 0.42Ω
Figure 1.8
Efficiency vs. VOUT with RS = 0.88Ω
100
100
90
80
70
60
90
80
70
60
VIN=12V,RS=0.88Ω,L=10µH
VIN=24V,RS=0.42Ω,L=10µH
50
12
50
25
15
18
21
24
27
30
26
27
28
29
30
VOUT (V)
VOUT (V)
Figure 1.9
VFB Reverence Voltage vs. VIN
Figure 1.10
IOUT vs. PWM Duty Cycle
320
(For details of PWM dimming, see section 2.2.3.)
400
310
300
290
280
270
260
350
300
250
200
150
100
50
500Hz
10KHz
250
6
10
14
18
VIN (V)
22
26
30
0
0
20
40
60
80
100
120
PWM Duty Cycle (%)
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ZLED7015 Datasheet
1.5
Characteristic Waveforms
Figure 1.11 VOUT, VIN, and IL1 during Soft Start
VOUT
10V/Div
VIN
10V/Div
IL1
Inductor
Current
1A/Div
VIN = 12VDC, RS = 0.88Ω, L1 = 10µH, VOUT = 28V
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ZLED7015 Datasheet
Figure 1.12 VOUT, VLX, and IOUT during Typical Operation
VOUT
20V/Div
VLX
20V/Div
IOUT
20mA/Div
VIN = 12VDC, RS = 0.88Ω, L1 = 10µH, VOUT = 28V
2μs/Div
Figure 1.13 VOUT, VLX, and IL1 when Over-Voltage Protection (OVP) Threshold is Exceeded
VOUT
20V/Div
VLX
20V/Div
IL1
500mA/Div
VIN = 12VDC, RS = 0.88Ω, L1 = 10µH, VOUT = 28V, VOVP = 33V
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ZLED7015 Datasheet
2
Circuit Description
The ZLED7015 is a constant-current boost converter that can also function as a constant voltage driver for LED
applications. The boost converter topology features an internal 35V power switch and feedback circuit to control
the output to the LED string. Optimal performance is achieved by operating in continuous conduction mode within
the application’s load current range; i.e., the current through inductor L1 is always above 0A. The output current is
set by an external resistor and the device supports DC linear or PWM dimming. Additional device features include
selectable open-load/over-voltage protection, over-temperature protection, under-voltage lockout, and an
automatic soft-start function to minimize the inrush current during startup.
2.1
EN Pin, VP Pin, and Soft-Start Function
The EN pin can be used to enable or disable the ZLED7015. When the voltage on the EN pin rises above the ON
threshold voltage VENon specified in Table 1.3, the ZLED7015 begins its “soft-start.” When the voltage at EN falls
below the OFF threshold voltage VENoff, the ZLED7015 shuts down. There is a hysteresis between VENon and VENoff
to prevent intermittent operation.
The ZLED7015’s internal “soft-start” function ensures a smooth device start-up by preventing excessive in-rush
current and providing a controlled rise in the output current. When the soft-start function is initiated, the internal
circuitry clamps the internal switch current threshold to zero during a 1millisecond delay. The soft-start function
then gradually increases the internal switch current threshold over a 4-5 msec period. See Figure 1.11 for an
illustration of typical waveforms during start-up.
Important: The EN pin requires termination. If the EN pin is not used to control operation, connect it to the
positive power supply through a 100kΩ resistor. Do not allow the EN pin to float.
The VP pin is connected to the ZLED7015’s internal power regulator and requires an external bypass capacitor,
CVP, to ensure correct device operation.
2.2
Output Current Control
The LED current is determined by the voltage across the external sense resistor RS, which is fed back to the input
FB. Internally, this is compared with the internal feedback reference voltage, VFB (see typical application shown on
page 2), and the duty cycle of the internal power switch is adjusted to reduce or increase the output current IOUT
.
Selection of RS is discussed in section 2.2.1, and other external components are discussed in section 3. Dimming
can be controlled by superimposing a DC or filtered pulse-width modulated (PWM) signal on the feedback voltage
from RS. Refer to sections 2.2.2 and 2.2.3, respectively, for more details.
2.2.1
Output Current and RS
The ZLED7015 continually adjusts the output current, IOUT, in order to maintain the voltage level at the FB pin
equal to the internal feedback reference voltage, VFB. Equation (1) shows the basic relationship between IOUT, VFB,
and RS for the basic application shown in Figure 2.1.
VFB 0.3V
IOUT
=
=
RS
RS
(1)
Where
IOUT = Average output current through the LED(s) in amperes
VFB = Internal feedback reference voltage (see Table 1.3, parameter 1.3.7)
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ZLED7015 Datasheet
Figure 2.1
Typical Application Circuit
VIN = 6 to 30 VDC
VOUT
L1
D1
REN
R1
R2
CIN
LED
String
C2
EN
LX
RVDD
C1
VDD
OVP
COVP
COUT
FB
VP
CVDD
ZLED7015
AGND
PGND
CVP
RS
2.2.2
Dimming via External DC Voltage Control
The LED output current can be set below the nominal average value defined on section 2.2.1 by using an external
DC voltage control signal superimposed on the FB pin as shown in the example circuit in Figure 2.2. As the DC
control signal, VDC, increases, the current through R3 increases with a subsequent increase in the voltage at the
FB pin. This causes the ZLED7015 to compensate by reducing the output current through the LED string.
Consequently, the output current is inversely proportional to the DC control voltage.
Note: It is important to ensure that the LED output voltage VOUT remains higher than the input voltage VIN in
dimming applications.
Figure 2.2
Example Circuit for Controlling Output Current via an External DC Control Voltage
VIN = 6 to 30 VDC VOUT
L1
D1
REN
R1
R2
CIN
LED
String
C2
RVDD
EN
VDD
LX
C1
OVP
COVP
COUT
FB
VP
R3
CVDD
ZLED7015
PGND
AGND
CVP
RS
R4
DC Control Signal VDC = 0 to 5V
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ZLED7015 Datasheet
The output current controlled by the DC voltage on FB can be calculated using equation (2):
R3 ×
(
VDC −VFB
R4
)
VFB −
(2)
IOUT
=
RS
Where
OUT = Output current through the LED(s) with a DC control voltage
I
VFB = Internal feedback reference voltage (Table 1.3, parameter 1.3.7)
VDC = External DC control voltage
2.2.3
Dimming via PWM Control
An external pulse-width modulated (PWM) signal input can be used to control the LED output current by driving
the output current to a value below the nominal average value defined in section 2.2.1. A microcontroller can be
used to generate the PWM signal. See Figure 2.3 for an example circuit. The PWM signal is superimposed on the
feedback voltage from RS at the FB pin via the input filter R5/C3 and R4, which produces a DC voltage with a
ripple. This method of controlling dimming is similar to the external DC voltage control described in section 2.2.2.
The duty cycle of the PWM signal regulates the filtered DC voltage level, which inversely controls the LED output
current level. When the duty cycle is at 100%, the output current is at the minimum. With a 0% duty cycle, the
output current is at the maximum.
Recommendation: With a PWM signal of 0 to 5V, use an R3 value of 10kΩ and a PWM frequency of >2kHz to
minimize the filtered PWM voltage ripple.
Note: It is important to ensure that the LED output voltage VOUT remains higher than the input voltage VIN in
dimming applications.
Figure 2.3
Example Circuit for Controlling Output Current via a PWM Control Signal
VIN = 6 to 30 VDC
L1
D1
REN
R1
CIN
LED
String
C2
EN
LX
RVDD
C1
VDD
OVP
R2
COVP
COUT
FB
VP
R3
CVDD
ZLED7015
PGND
AGND
CVP
RS
R4
C3
R5
5V
0V
Microcontroller PMW Signal
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ZLED7015 Datasheet
The output current controlled by the PWM voltage on FB can be calculated using equation (3):
R3 ×
(
VPWM × DPWM −VFB
)
VFB −
(3)
R + R5
4
IOUT
=
R
S
Where
OUT = Output current through the LED(s) with a PWM control voltage
I
VFB = Internal feedback reference voltage (see Table 1.3, parameter 1.3.7)
VPWM = External PWM control voltage
DPWM = Duty cycle of the PWM control signal
2.2.4
Microcontroller LED Control
A microcontroller can control the LED output current by providing a PWM control signal to the FB pin as described
in section 2.2.3.
Depending on the application, the microcontroller can also be used to control the shutdown circuitry via the EN
pin (see section 2.1) providing a fast and smooth transition to shutdown.
2.2.5
Constant Voltage Application
In addition to functioning as a constant-current boost converter for driving an LED string, the ZLED7015 can be
configured as a constant-voltage boost converter for other applications. Figure 2.4 demonstrates a typical circuit
for this application.
The output voltage controlled by the values of R3 and RS can be calculated using equation (4):
(R + R )
3
S
(4)
VOUT =VFB ×
R
S
Where
VOUT = Output voltage to the load
VFB = Internal feedback reference voltage (Table 1.3, parameter 1.3.7)
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ZLED7015 Datasheet
Figure 2.4
Example Circuit for Constant Voltage Source Applications
VIN = 6 to 30 VDC
L1
D1
REN
R1
R3
CIN
C2
EN
LX
FB
RVDD
Load
C1
VDD
OVP
VP
COUT
CVDD
ZLED7015
PGND AGND
RS
CVP
R2
COVP
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3
Application Circuit Design
The following sections cover selection of the external components shown in the typical application on page 1.
3.1
External Component – RS
Recommendation: Use precision resistors (±1% or better tolerance) for the RS resistor to ensure accurate control
of the LED current.
See section 2.2.1 for the equation for selecting the value of RS, which sets the nominal current output.
3.2
External Component – Inductor L1
Designing the circuit so that the current through inductor L1 is always above 0V (i.e., continuous mode) typically
gives the best performance due to improved load regulation and reduced output ripple. Select an inductor that has
a saturation current and a current rating greater than the mean input current.
The inductor value selection requires trade-offs between unwanted ripple current and parasitic effects. A larger
value inductor reduces inductor ripple current, resulting in less output ripple voltage; however, higher values also
increase parasitic resistance, which can degrade performance. For most applications, a 10µH inductor with a
saturation current >2.5A is adequate. See section 7.4 for layout restrictions.
3.3
External Components – Input Decoupling Capacitors C1 and CIN
The input capacitors C1 and CIN minimize the input voltage noise and ripple. Recommendation: use a 22µF or
larger low-ESR electrolytic capacitor for CIN in parallel with a 1µF ceramic capacitor rated at greater than the input
voltage plus a safety margin for C1.
3.4
External Component –Output Capacitors C2 and COUT
The output capacitors C2 and COUT minimize the output voltage ripple. Recommendation: use a 22µF or larger
low-ESR electrolytic capacitor for COUT in parallel with a 1µF ceramic capacitor rated at greater than the output
voltage plus a safety margin for C2.
3.5
External Component – Diode D1
For the diode D1, select a high-speed, low-capacitance Schottky diode with low reverse leakage at the maximum
operating voltage and temperature to ensure maximum efficiency and performance.
Important: Choose diodes with a continuous current rating higher than the maximum output load current and a
peak current rating above the peak coil current. When operating above 85°C, the reverse leakage of the diode
must be addressed because it can cause excessive power dissipation in the diode, especially when the output
voltage is relatively high. Its reverse breakdown voltage must be greater than the over-voltage protection level
VOVP (see section 4.2).
Note: Silicon diodes have higher forward voltage and higher voltage overshoot before they start conducting, which
can increase the peak voltage on the LX output. Ensure that the total voltage appearing on the LX pin, including
supply ripple, is within the specified range (see Table 1.1).
3.6
Additional External Components
For the VDD input, connect resistor RVDD to the positive power supply and connect ceramic capacitor CVDD to
ground. Recommendations: use 1µF for CVDD; use 300Ω for RVDD with input voltages ≥ 8V, use 50Ω for RVDD with
input voltages < 8V.
For the VP pin, connect a 10µF ceramic bypass capacitor to ground (CVP).
If the EN pin is not used, connect a 100kΩ resistor to the positive power supply (REN). Do not allow the EN pin to
float.
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4
Operating Conditions
4.1
Under-Voltage Lockout
The under-voltage lockout (UVLO) monitors the ZLED7015’s internal regulator output voltage, VP, to ensure
correct operation of the internal circuitry. When the VP voltage is lower than the UVLO threshold VUVLO, the
ZLED7015 disables the internal power switch. If the VP voltage reaches a level higher than the UVLO threshold
plus UVLO hysteresis (VUVLO+VUVLO_HYS) the UVLO turns off and the internal power switch is re-enabled. See
parameters 1.3.14 and 1.3.15 in section 1.3 for the UVLO threshold and hysteresis.
4.2
Over-Voltage Threshold and Open-Circuit Protection
If the LED string becomes open or the FB pin is shorted to ground, the ZLED7015 would normally continually
boost the output voltage to potentially damaging levels. To prevent this, the ZLED7015 includes an integrated
over-voltage protection (OVP) mechanism. If the output voltage reaches the ZLED7015’s OVP threshold VOVP, the
protection circuitry is triggered and the device automatically turns off the internal switch, stopping the boost
function and protecting the device. Once the output voltage falls below the OVP threshold minus OVP threshold
hysteresis (VOVP_TH-VOVP_TH_HYS), the device will enter soft-start mode.
The OVP threshold VOVP for the ZLED7015 is selectable via the R1 and R2 resistor values determined by
equation (5):
(R + R2 )
1
VOVP =VOVP_TH
×
(5)
R2
Where
VOVP = Over-voltage protection threshold
VOVP_TH = Internal over-voltage threshold reference voltage (see Table 1.3, parameter 1.3.16)
Important: Care must be taken to select proper R1 and R2 values to ensure proper functioning of the ZLED7015.
See specification 1.3.16 in Table 1.3 for the over-voltage protection threshold voltage. Set VOVP 3V higher than
the normal operation output voltage.
Important: When setting VOVP, care must be taken to ensure VOUT cannot exceed 35V.
Minimize noise coupling on the OVP pin, which could interfere with proper protection, by connecting a 10nF
ceramic capacitor to GND from OVP (COVP).
4.3
Over-Temperature Protection
The ZLED7015 features on-chip over-temperature protection. If its internal temperature exceeds the over-
temperature protection (OTP) threshold, TOTP, due to high power dissipation and improper heat sinking, the
internal power switch is disabled. Once the internal temperature has fallen below the OTP threshold minus the
OTP threshold hysteresis (TOTP - TOTP_HYS), the ZLED7015 enters the soft-start mode (see section 2.1).
Refer to Table 1.1 for the maximum package power dissipation specifications for the ZLED7015’s MSOP-10
package.
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5
ESD/Latch-Up-Protection
All high voltage pins (1, 4, 5, 9, and 10) have an ESD protection of >± 2500V according to the Human Body Model
(HBM). The ESD test follows the Human Body Model based on MIL 883-H, Method 3015.8
All low voltage pins (2, 3, 6, 7, and 8) have an ESD protection of >± 4000V according to the Human Body Model
(HBM). The ESD test follows the Human Body Model based on MIL 883-H, Method 3015.8
All pins pass the latch-up test based on the JEDEC Standard No. 78B, December 2008.
6
Pin Configuration and Package
The ZLED7015 package is an MSOP-10, which has a thermal resistance (junction to ambient) of
θJA = 60°C/W.
R
Figure 6.1
ZLED7015 Pin Configuration—MSOP-10 Package
PGND
VP
LX
VDD
NC
AGND
EN
FB
AGND
OVP
Table 6.1
Pin Name
PGND
Pin Description MSOP-10
No.
Description
1
2
Power ground
VP
Internal 5V linear regulator output. VP is the power supply for the internal switch gate driver and the
internal control circuitry. Use a 10µF ceramic bypass capacitor between VP and ground.
AGND
EN
3
4
5
6
7
Analog (signal) ground.
Enable control input. Important: Do not allow this pin to float.
Analog (signal) ground.
AGND
OVP
FB
Over-voltage protection control input.
Feedback voltage input. The nominal average output current is set by the value of RS connected from
FB to GND – see section 2.2.1 for details. Important: Do not allow the FB pin to float.
n.c.
VDD
LX
8
9
No connection
Supply voltage (6V to 30V)—see section 7 for layout considerations.
10 Drain of the internal switch. Connect the power inductor between LX and the power supply. Connect the
output rectifier D1 between LX and the output circuit. See section1.1 for output range specifications.
Thermal
Pad
Connect to ground.
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Figure 6.2
MSOP-10 Package Dimensions for the ZLED7015
Dimension (mm, except θ)
Dimension (mm)
Symbol
Symbol
Min
0.82
0.02
0.75
0.18
0.09
Max
1.10
0.15
0.95
0.28
0.23
Min
2.90
1.70
Max
3.10
1.90
D
A
A1
A2
b
D1
e
0.50 BSC
E
2.90
4.75
1.45
0.40
3.10
5.05
1.65
0.80
E1
E2
L
c
θ
0°
6°
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7
Layout Requirements
Follow these layout guidelines to avoid circuit instability and EMI vulnerability, especially with high current or high
switching frequency applications.
Important: Route traces connecting the feedback network to the FB and OVP pin away from the L1 inductor, the
D1 Schottky diode, and the LX pin. These traces should be as short as possible. Shield the FB pin and feedback
network with a ground plane or trace to prevent noise coupling.
7.1
General Considerations and Ground Traces
Make the ground traces as wide and short as possible. To prevent a signal ground shift, keep traces for the signal
ground (pin 5) separate from traces for the power ground (pin 1). Connect the signal and power ground traces
together at either the large ground plane or the negative terminal of CIN.
Connect the grounds for other components to the signal ground.
Use wide traces for connection of the high current loop.
7.2
Layout Considerations for C1, CIN, C2 and COUT
Place C1, C2 and COUT as close as possible to the ZLED7015 to minimize ripple. The CIN input decoupling
capacitor must be placed as close as possible to the VDD pin to minimize power supply noise, which can reduce
efficiency.
7.3
Layout Considerations for the EN Pin
Important: Do not allow the EN pin to float. It must be terminated if it is not used.
7.4
Layout Considerations for the LX Pin, L1 External Coil, and D1 Diode
Minimize the length of circuit board traces connected to the LX pin because it is a fast switching output.
Place L1 and D1 as close as possible to the LX pin using traces that are as short and wide as possible. Avoid
routing other traces crossing or in parallel with this node to minimize the noise coupling into this circuit.
7.5
Layout Considerations for the External Current Sense Resistor (RS)
Any trace resistance in series with RS must be taken into consideration when selecting its value. For the most
accurate LED current control, use a trace that is as wide and short as possible for the RS connection to ground.
Connect it to the signal ground (pin 5), not the power ground (pin 1).
7.6
Layout Considerations for CVP and CVDD
For good filtering, connect CVP as close as possible to the VP pin and place CVDD as close as possible to the VDD
pin.
7.7
Layout Considerations for the Thermal Pad
To optimize heat dissipation, solder the thermal pad on the back of the MSOP-10 package to the large ground
plan.
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8
9
Glossary of Terms
Term
Definition
LDO
OTP
OVP
UVL
Low Dropout Regulator
Over-Temperature Protection
Over-Voltage Protection
Under-Voltage Lockout
Ordering Information
Product Sales Code
Description
ZLED7015 – 1MHz Boost Converter with Internal 35V Switch
Package
ZLED7015ZI1R
MSOP-10 (Tape & Reel)
ZLED7015KIT-E1
ZLED7015-E1 Evaluation Board, 1 ZLED-PCB10, and 5 ZLED7015 ICs Kit
10 Document Revision History
Revision
Date
Description
1.00
December 20, 2011 First Issue.
April 20, 2016
Changed to IDT branding.
Corporate Headquarters
6024 Silver Creek Valley Road
San Jose, CA 95138
Sales
Tech Support
www.IDT.com/go/support
1-800-345-7015 or 408-284-8200
Fax: 408-284-2775
www.IDT.com/go/sales
www.IDT.com
DISCLAIMER Integrated Device Technology, Inc. (IDT) reserves the right to modify the products and/or specifications described herein at any time, without notice, at IDT's sole discretion. Performance
specifications and operating parameters of the described products are determined in an independent state and are not guaranteed to perform the same way when installed in customer products. The
information contained herein is provided without representation or warranty of any kind, whether express or implied, including, but not limited to, the suitability of IDT's products for any particular purpose, an
implied warranty of merchantability, or non-infringement of the intellectual property rights of others. This document is presented only as a guide and does not convey any license under intellectual property
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Integrated Device Technology, IDT and the IDT logo are trademarks or registered trademarks of IDT and its subsidiaries in the United States and other countries. Other trademarks used herein are the
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