AT9919DB1 User Guide

Supertex inc.
AT9919DB1
Single, High Current, LED Driver Demoboard
General Description
The AT9919BDB1 demoboard is a high current LED driver
designed to drive one LED at 1.0A from a 9.0 - 16VDC input.
The demoboard uses Supertex’s AT9919 hysteretic buck
LED driver IC.
The AT9919DB1 includes two PWM dimming modes. The
analog control of the PWM dimming mode allows the user to
dim the LED using a 0 - 2.0V analog signal applied between
the ADIM and GND pins (0V gives 0% and 2.0V gives 100%).
In this mode, the PWM dimming frequency is set to 1kHz on
the board. The digital control of PWM dimming mode allows
the user to dim the LEDs using an external, TTL-compatible
square wave source applied between DIM and GND. In this
case, the PWM dimming frequency and duty ratio are set by
the external square wave source.
Specifications
Parameter
Input voltage
Connections
Input Connection: Connect the input DC voltage between
VIN and GND terminals of connector J1 as shown in the
connection diagram.
Output Connection: Connect the LEDs between LED+
(anode of LED string) and LED- (cathode of LED string) of
connector J2.
PWM Dimming Connection:
1. If no PWM dimming is required, short DIM, VDD and
ADIM terminals of connector J3.
Doc.# DSDB-AT9919DB1
A032713
9.0 - 16VDC (steady state)
40V max (transient)
Reverse polarity protection
60V (max)
Output voltage
2.0 - 5.0V
Output current
1.0A ± 5%
Output current ripple (@13.5V
input and 3.3V output)
Full load efficiency
(@13.5V input)
16% (peak to peak)
84%
Open LED protection
Yes
Output short circuit protection
Yes
Dimensions
Connection Diagram
Value
25.4mm X 25.4mm
Silk Screen
2. If dimming using an external PWM dimming source,
connect the PWM source between the DIM and GND
terminals of connector J3 and short terminals ADIM
and VDD. The recommended PWM dimming frequency is ≤1.0kHz.
3. If dimming using an external analog voltage source,
connect the source between the ADIM and GND terminals of connector J3 and short terminals DIM and
VDD. The voltage range for control of the PWM dimming is 0 - 2.0V.
Supertex inc.
www.supertex.com
AT9919DB1
Typical Results
Fig. 1. Efficiency vs. Input Voltage Plot
Fig. 2. Line Regulation of LED Current Plot
1.0
85.0
% change in LED Current
0.8
Efficiency (%)
84.8
84.6
84.4
84.2
84.0
8
10
12
14
Input Voltage (V)
16
18
-0.2
-0.4
-0.6
75
70
2
3
4
(Full Load)
Switching Frequency (kHz)
350
300
250
200
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14
18
16
2
3
4
Load Voltage (V)
5
(@13.5V input)
400
12
16
Fig. 6. Switching Frequency vs. Load Voltage Plot 400
Input Voltage (V)
14
0
450
10
12
Input Voltage (V)
0.5
450
8
10
1.0
-0.5
5
Load Voltage (V)
Fig. 5. Switching Frequency vs. Input Voltage Plot
150
8
1.5
% change in LED Current
Efficiency (%)
0
Fig. 4. Load Regulation of LED Current Plot
80
Switching Frequency (kHz)
0.2
-1.0
85
0.4
-0.8
Fig. 3. Efficiency vs. Load Voltage Plot
(@13.5V input)
65
0.6
350
300
250
200
150
18
2
3
4
Load Voltage (V)
5
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AT9919DB1
Typical Waveforms (All waveforms are at 13.5V input and 3.3V LED Voltage unless otherwise noted)
Figure 7.
Steady State Waveforms
Drain Voltage
LED Current
C1 (Yellow)
C4 (Green)
Time Scale
Figure 8.
:
:
:
Drain Voltage (5V/div)
LED Current (500mA/div)
1μs/div
Transient Response of the LED Current
Input Voltage
LED Current
C1 (Yellow)
C4 (Green)
Time Scale
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:
:
:
Input Voltage (20V/div)
LED Current (500mA/div)
20μs/div
Supertex inc.
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AT9919DB1
Typical Waveforms (All waveforms are at 13.5V input and 3.3V LED Voltage unless otherwise noted)
Figure 9.
PWM Dimming using the DIM input
PWM Dimming Input
LED Current
(a) PWM Dimming Performance
Time Scale
:
1ms/div
PWM Dimming Input
PWM Dimming Input
LED Current
LED Current
(b) PWM Dimming Rise Time
Time Scale
:
10µs/div
C1 (Yellow)
C4 (Green)
Figure 10.
(c) PWM Dimming Fall Time
Time Scale
:
:
:
10µs/div
PWMD Input Voltage (5V/div)
LED Current (500mA/div)
PWM Dimming using the ADIM pin
RAMP Voltage
ADIM Voltage
LED Current
C1 (Yellow)
C2 (Pink)
C4 (Green)
Time Scale
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A032713
:
:
:
:
ADIM Voltage (1V/div)
RAMP Voltage (1V/ div)
LED Current (500mA/div)
200μs/div
Supertex inc.
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AT9919DB1
AT9919DB1 Schematic Diagram
D2
J1
C6
4.7µF
25V
2
2
2.2µH
(LPS3008-222)
B160
1
L2
1
C2
4.7uF
25V
C1
4.7uF
25V
D1
STPS2L60A
R1
0.2
1/2W
C3
1.0uF
25V
Input
4
C4
1.0n
J3A
2
1
J3B
U1
R5
1.0k
R4
10k
D4
4.7V
J3D
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A032713
3
5
3
2
1
Output
C7
1.0n
J3C
J2
1
2
1
VIN
CS
ADIM
AT9919
R2
0.0
GT 8
RAMP
GND
DIM
TAB
Q1
Si7308DN
2
L1
22µH
(DRA74-220)
7
9
VDD
6
C5
1.0uF
10V
Supertex inc.
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AT9919DB1
Bill of Materials
Item #
Qty
RefDes
Description
Package
Manufacturer
Manufacturer’s Part
Number
1
3
C1, C2,
C6
4.7µF, 25V, 10%
X7R ceramic capacitor
SMD1206
Murata
GRM31CR71E475KA88L
2
1
C3
1.0µF, 25V, 10% X7R
ceramic capacitor
SMD1206
Kemet
C1206C105K3RACTU
3
2
C4, C7
1.0nF, 50V, 5%, C0G
ceramic capacitor
SMD0603
TDK Corp
C1608C0G1H102J
4
1
C5
1.0µF, 10V, 10% X7R
ceramic capacitor
SMD0603
Taiyo Yuden
LMK107B7105KA-T
5
1
D1
60V, 2A schottky diode
SMA
ST Micro
STPS2L60A
6
1
D2
60V, 1A schottky diode
SMA
ST Micro
STPS1L60A
7
1
D4
4.7V, 350mW zener diode
SOT-23
Diodes Inc
BZX84C4V7-7-F
8
2
J1, J2
2 position, 5mm pitch,
vertical header
Thru-Hole
On Shore Tech
EDSTL130/02
9
1
J3
4 position, 0.100” pitch,
vertical header
Thru-Hole
Molex
22-03-2041
10
1
L1
22µH, 1.8A rms,
1.7A sat inductor
SMT
Coiltronics
DRA74-220-R
11
1
L2
2.2µH, 1.0A rms,
1.0A sat inductor
SMT
Coilcraft
LPS3008-222
12
1
Q1
60V, 72mΩ, 9nC
N-channel FET
Powerpak
1212-8
Vishay
SI7308DN-T1-E3
13
1
R1
0.2Ω, 1/2W, 1% chip resistor
SMD1210
Rohm
MCR25JZHFLR200
14
1
R2
0.0Ω, 1/10W, 5% chip resistor
SMD0603
Panasonic
ERJ-3GEY0R00V
15
1
R4
10kΩ, 1/10W, 5% chip resistor
SMD0603
Panasonic
ERJ-3GEYJ103V
16
1
R5
1kΩ, 1/10W, 5% chip resistor
SMD0603
Panasonic
ERJ-3GEYJ102V
17
1
U1
Hysteretic Buck LED Driver
DFN-8
Supertex
AT9919
Supertex inc. does not recommend the use of its products in life support applications, and will not knowingly sell them for use in such applications unless it receives
an adequate “product liability indemnification insurance agreement.” Supertex inc. does not assume responsibility for use of devices described, and limits its liability
to the replacement of the devices determined defective due to workmanship. No responsibility is assumed for possible omissions and inaccuracies. Circuitry and
specifications are subject to change without notice. For the latest product specifications refer to the Supertex inc. (website: http//www.supertex.com)
Supertex inc.
©2013 Supertex inc. All rights reserved. Unauthorized use or reproduction is prohibited.
Doc.# DSDB-AT9919DB1
A032713
6
1235 Bordeaux Drive, Sunnyvale, CA 94089
Tel: 408-222-8888
www.supertex.com
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