Supertex inc.
General Description
Specifications
Parameter
Input voltage
Reverse polarity protection
Output voltage
Output current
Output current ripple (@13.5V
input and 3.3V output)
Full load efficiency
(@13.5V input)
Open LED protection
Output short circuit protection
Dimensions
AT9919DB1
Single, High Current, LED Driver Demoboard
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.
Value
9.0 - 16VDC (steady state)
40V max (transient)
60V (max)
2.0 - 5.0V
1.0A ± 5%
16% (peak to peak)
84%
Yes
Yes
25.4mm X 25.4mm
Connection Diagram
Silk Screen
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
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 frequen-
cy is ≤1.0kHz.
3. If dimming using an external analog voltage source,
connect the source between the ADIM and GND ter-
minals of connector J3 and short terminals DIM and
VDD. The voltage range for control of the PWM dim-
ming is 0 - 2.0V.
Supertex inc.
www.supertex.com
AT9919DB1
Typical Results
Fig. 1. Efficiency vs. Input Voltage Plot
85.0
Fig. 2. Line Regulation of LED Current Plot
1.0
0.8
84.8
% change in LED Current
8
10
12
14
16
18
0.6
0.4
0.2
Efficiency (%)
84.6
0
-0.2
-0.4
-0.6
-0.8
84.4
84.2
84.0
Input Voltage (V)
-1.0
8
10
Input Voltage (V)
12
14
16
18
Fig. 3. Efficiency vs. Load Voltage Plot
(@13.5V input)
85
Fig. 4. Load Regulation of LED Current Plot
1.5
80
% change in LED Current
2
3
4
5
1.0
Efficiency (%)
75
0.5
70
0
65
-0.5
Load Voltage (V)
2
Load Voltage (V)
3
4
5
Fig. 5. Switching Frequency vs. Input Voltage Plot
(Full Load)
450
Fig. 6. Switching Frequency vs. Load Voltage Plot
(@13.5V input)
450
Switching Frequency (kHz)
350
300
250
200
150
Switching Frequency (kHz)
8
10
12
14
16
18
400
400
350
300
250
200
150
Input Voltage (V)
2
Load Voltage (V)
3
4
5
Doc.# DSDB-AT9919DB1
A032713
Supertex inc.
2
www.supertex.com
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
Time Scale
PWM Dimming Input
(a) PWM Dimming Performance
:
1ms/div
PWM Dimming Input
LED Current
LED Current
(b) PWM Dimming Rise Time
(c) PWM Dimming Fall Time
Time Scale
:
10µs/div
C1 (Yellow)
C4 (Green)
:
:
Time Scale
:
10µs/div
PWMD Input Voltage (5V/div)
LED Current (500mA/div)
Figure 10.
PWM Dimming using the ADIM pin
RAMP Voltage
ADIM Voltage
LED Current
C1 (Yellow)
C2 (Pink)
C4 (Green)
Time Scale
:
:
:
:
ADIM Voltage (1V/div)
RAMP Voltage (1V/ div)
LED Current (500mA/div)
200μs/div
Doc.# DSDB-AT9919DB1
A032713
Supertex inc.
4
www.supertex.com
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