HV9912DB1 User Guide

Supertex inc.
HV9912DB1
High Brightness Boost LED Driver Demoboard
with 1:3000 Dimming Ratio and Hiccup Mode Protection
General Description
The HV9912DB1 is an LED driver demoboard capable of driving up
to 20 one-watt LEDs in series from an input of 21 - 27VDC. It uses
the Supertex HV9912 in a boost topology. The converter has very
good initial regulation (+/-5%) and excellent line and load regulation
over the entire input and output voltage range (<+/- 1%). The full
load efficiency of the converter is typically greater than 90%.
Specifications
Parameter
Input voltage (steady state):
Output LED string voltage:
Output current:
Value
21 - 27VDC
35V min - 80V max
350mA +/-5%
Output current ripple:
10% typical
The HV9912DB1 is protected against open LED and output short
circuit conditions. It is also protected under input under-voltage
conditions by limiting the input current. It has an excellent PWM
dimming response, with typical rise and fall times less than 1.0μs,
which allows high PWM dimming ratios. The switching frequency of
the HV9912DB1 can be synchronized to other HV9912 boards or
to an external 200kHz clock by connecting the clock to the SYNC
pin of the HV9912DB1.
Switching frequency:
200kHz
The HV9912DB1 features hiccup mode short circuit and open LED
protection. Upon detection of either fault condition, the IC shuts
down the driver and periodically attemps to restart until the fault
condition ends. The HV9912DB1 also features a built-in 500ns
blanking to prevent false tripping of the over-current comparator
due to parasitic capacitance spikes during PWM dimming.
PWM dimming:
Full load efficiency:
93% (at 24V input)
Open LED protection:
Shuts down at 92V
Output short circuit
protection:
Included
Input under voltage
protection:
Included
1:3000 dimming ratio
at 200Hz
Board Layout and Connection Diagram
VIN
+
Actual size: 64.0mm x 34.5mm
Connections
Input - The input is connected between the terminals of
connector J1 as shown in the Connection Diagram.
Output - The output is connected between the terminals of
connector J2 as shown.
Enable/PWM Dimming - To just enable the board, short pins
PWMD and VDD of connector J3 as shown by the dashed
lines. To PWM dim the board, connect the external pushpull waveform source between terminals PWMD and GND
of connector J3 as shown by the solid lines.
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A032913
SYNC - To synchronize two or more boards, connect the
SYNC pins of all the boards together. To synchronize the
HV9912DB1 to an external 200kHz clock, connect the clock
between the SYNC and GND pins of terminal J3.
Note:
During PWM dimming, pin 2 of connector J3 should be left
open. Also, the PWM signal must have the proper polarity
with the positive connected to pin 3 of J3. Note that pin 4
of J3 is internally connected to the return path of the input
voltage.
Supertex inc.
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HV9912DB1
Testing The Demoboard
Normal Operation: Connect the input source and the output
LEDs as shown in the Connection Diagram and enable the
board. The LEDs will glow with a steady intensity. Connecting
an ammeter in series with the LEDs will allow measurement
of the LED current. The current will be 350mA +/- 5%.
Efficiency (%)
95
Current Regulation: With the input power to the converter
disconnected, change the LED string voltage within
the specifications mentioned. The current output of the
HV9912DB1 will remain very steady over the entire load
range. Vary the input voltage while the circuit is operational.
The current will be regulated over the entire line range.
93
92
91
90
35
40
45
50
55
60
65
70
Output Voltage (V)
75
80
Fig. 1 Efficiency vs. Output Voltage
Efficiency (%)
95
Open LED test: Connect a voltmeter across the output
terminals of the HV9912DB1. Start the demoboard normally,
and once the LED current reaches steady state, unplug
one end of the LED string from the demoboard. The output
voltage will rise to about 92V and the HV9912DB1 will shut
down. Once the LED string is reconnected, the driver will
start regulating current.
94
93
92
91
90
20
22
24
26
Input Voltage (V)
28
Fig. 2 Efficiency vs. Input Voltage
2. Current Regulation: Figs. 3 and 4 show the output current regulation vs. output voltage and input voltage respectively. The total current regulation (line and load combined)
is found to be less than 1%.
Output Current (A)
Short Circuit Test: When the HV9912DB1 is operating in
steady state, connect a jumper across the terminals of the
LED string. Notice that the output current will immediately
go to zero and the converter will shut down. Removing the
jumper will cause the HV9912DB1 to restart and continue to
regulate the LED current.
PWM Dimming: With the input voltage to the board
disconnected, apply a TTL compatible, push-pull square wave
signal between PWMD and GND terminals of connector J3
as shown in the Connection Diagram. Turn the input voltage
back on and adjust the duty cycle and/or frequency of the
PWM dimming signal. The output current will track the PWM
dimming signal. Note that although the converter operates
perfectly well at 1.0kHz PWM dimming frequency, the widest
PWM dimming ratio can be obtained at lower frequencies
like 100 or 200Hz.
0.354
0.352
0.350
0.348
0.346
35
40
45
50
55
60
65
70
75
80
Output Voltage (V)
Output Current (A)
Fig. 3 Output Current vs. Output Voltage
Typical Results
1. Efficiency: The efficiency of the converter at various LED
string voltages are shown in Fig.1 (measured at the nominal
input voltage of 24V). Fig.2 shows the full load efficiency
of the converter at varying input voltages. The minimum efficiency of 93% for the converter occurs at 21V input and full
load output.
Doc.# DSDB-HV9912DB1
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94
0.354
0.352
0.350
0.348
0.346
20
22
24
26
28
Input Voltage (V)
Fig. 4 Output Current vs. Input Voltage
2
Supertex inc.
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HV9912DB1
0.4
1.6
0.3
1.4
0.2
1.2
0.1
Output Voltage
COMP Voltage
LED Current
Input Current (A)
Output Current (A)
3. Input Under Voltage Protection: Input under voltage
protection is provided by limiting the input current at low input voltages. Fig. 5 shows the output and input currents at
voltages less than the minimum rated voltage. The LED current will decrease as the input voltage falls and the input
current limits to about 1.4A. Note that the input current limit
is not a hard limit as the slope compensation added to the
peak current sense signal will allow a small change in the
input current with a decrease in the input voltage.
Fig. 7 Recovery from an Open LED Condition
1.0
25
20
15
Input Voltage (V), Sweep
Input Current
Fig. 7 shows the recovery of the HV9912DB1 from an over
voltage condition. In this case, the LED has reconnected
at some point when the converter is turned off. When the
converter attempts to restart, if finds the fault condition has
disappeared and it starts up normally. There is no overshoot
in the LED current .
10
Output Current
Fig. 5 Input Under-Voltage Behavior
4. Open LED Protection: Figs 6 and 7 show the hiccupmode over voltage protection. Fig. 6 shows the open LED
condition occurs when the LED current goes to zero. At
that point, the inductor current charges the output capacitor
and the COMP voltage rails to VDD. Once the output voltage reaches the over voltage threshold, the converter shuts
down and the output voltage slowly decays because the output capacitor is discharged by the over-voltage sensing resistor network. Once the output voltage falls to 90% of its trip
point, the converter tries to restart. Since the fault conditions
still persists, the converter shuts down almost immediately.
Thus, the HV9912 maintains the output voltage in a band
until the LED reconnects.
Short Circuit Protection: Figs 8 and 9 show the operation
of the short circuit protection in the HV9912DB1. In Fig. 8,
the onset of the output short circuit is indicated by the first
spike in the LED current. At this point, the HV9912DB1 shuts
down and the hiccup mode protection takes over. A constant
current source charges the COMP pin to 5.0V and then another current source discharges it to 1.0V. This charge/discharge cycle determines the hiccup time. When the COMP
pin reaches 1.0V, the converter attempts to restart and finding the fault condition still present, shuts down again.
Output Voltage
Output Voltage
COMP Voltage
COMP Voltage
LED Current
LED Current
Fig. 8 Short Circuit Condition
Fig. 6 Open LED Condition
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Supertex inc.
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HV9912DB1
Fig. 9 shows the recovery of the HV9912DB1 from a short
circuit condition. It can be seen that the LED current recovers normally with no overshoots.
at output voltages of 80V and 40V respectively. The timescale for all waveforms is set at 5.0μs/div. The rise and fall
times are less than 1.0μs in each case. Thus, a PWM dimming ratio of 1:3000 is achievable at a PWM dimming frequency of 200Hz.
6. PWM Dimming: The rise and fall transitions of the LED
current during PWM dimming are shown in Figs. 10 and 11,
PWM dimming input
PWM dimming input
Output Voltage
Output Voltage
LED Current
LED Current
Fig. 10a Rise time of LED Current at 80V output
Fig. 11a Rise time of LED Current at 40V output
(5.0μs/div)
(5.0μs/div)
PWM dimming input
PWM dimming input
Output Voltage
Output Voltage
LED Current
LED Current
Fig. 11b Fall time of LED Current at 40V output
Fig. 10b Fall time of LED Current at 80V output
(5.0μs/div)
(5.0μs/div)
Silk Screen
Doc.# DSDB-HV9912DB1
A032913
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Supertex inc.
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Doc.# DSDB-HV9912DB1
A032913
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REF
REF
J1A
J1B
1
2
J4
C6
0.1μF
16V
J5
R9
7.87kΩ
C8
6.8nF
C7
2.2nF
R13
8.66kΩ
REF
C1
2.2μF
25V
J6
R8
17.4kΩ
R7
20kΩ
IO_SNS
R12
16.2kΩ
J3A
C2
2.2μF
25V
J7
R4
OPEN
J3B
J3D
J3C
9
14
16
15
10
8
VIN
1
13
6
RT
R11
49.9kΩ
4
OVP
FAULT
CS
GATE
PWM SC GND
COMP
CLIM
VDD
2
HV9912
FDBK
IREF
REF
SYNC
C5
1.0μF
16V
L1
2
R5
1.0kΩ
IO_SNS
R6
0.15Ω
1/2W
Q2
FDS 3692
C4
1.0μF
100V
D1
B1100-13
C10
open
C9
1.0μF
100V
Input: 21 - 27VDC
Output Voltage: 40 - 80V
Output Current: 350mA
Overvoltage: 92V
Short Circuit Protection Included
Specifications:
12
11
5
3
7
R2
280kΩ
220μH
(CDRH127/LDNP-221MC)
1
R14
short
R3
49.9kΩ
J2B
C11
10nF
J2A
R10
1.24Ω
1/4W
Q1
TN251DN8
2
R1
866kΩ
1
HV9912DB1
Circuit Schematic:
Supertex inc.
www.supertex.com
HV9912DB1
Bill of Materials
#
Quan Ref Des Description
Package
Manufacturer
Manufacturer’s Part
Number
SMD1210
TDK Corp
C3225X7R1H225K
1
2
C1,C2
2.2µF, 25V, X7R ceramic chip capacitor
2
2
C4,C9
1µF, 100V metal polyester capacitor
Radial
EPCOS Inc
B32522C1105J
3
1
C5
1µF, 16V X7R ceramic chip capacitor
SMD0805
TDK Corp
C2012X7R1C105K
4
1
C6
0.1µF, 16V X7R ceramic chip capacitor
SMD0805
Murata
GRM219R71C104KA01D
5
1
C7
SMD0805
TDK Corp
C2012C0G1H222J
6
1
C8
SMD0805
TDK Corp
C2012C0G1H682J
7
1
C11
10nF, 50V X7R ceramic chip capacitor
SMD0805
TDK Corp
C2012X7R1H103K
8
1
D1
100V, 1.0A schottky diode
SMA
Diodes Inc.
B1100-13
9
2
J1,J2
Side Entry 2-pin male header
Thru-Hole
JST Sales
S2B-EH
10
1
J3
Side Entry 4-pin male header
Thru-Hole
JST Sales
S4B-EH
11
1
L1
220µH, 2.0A sat, 1.5A rms inductor
SMT
Sumida
CDRH127/LDNP-221MC
12
1
Q1
100V, 4.55A N-Channel MOSFET
SO-8
Fairchild
FDS3692
13
1
Q2
100V, 1.5Ω N-Channel MOSFET
SOT-89
Supertex
TN2510N8
14
1
R1
866kΩ, 1%, 1/8W chip resistor
SMD0805
Yageo
RC0805FR-07866KL
15
1
R2
280kΩ, 1%, 1/8W chip resistor
SMD0805
Yageo
RC0805FR-07280KL
16
2
R3, R11 49.9kΩ, 1%, 1/8W chip resistor
SMD0805
Yageo
RC0805FR-0749K9L
17
1
R4, C10 open
---
---
---
18
1
R5
1.0kΩ, 1%, 1/8W chip resistor
SMD0805
Yageo
RC0805FR-071KL
19
1
R6
0.15Ω, 1%, 1/2W chip resistor
SMD2010
Vishay/ Dale
WSL2010R1500FEA
20
1
R7
20kΩ, 1%, 1/8W chip resistor
SMD0805
Yageo
RC0805FR-0720KL
21
1
R8
17.4kΩ, 1%, 1/8W chip resistor
SMD0805
Yageo
RC0805FR-0717K4L
22
1
R9
7.87kΩ, 1%, 1/8W chip resistor
SMD0805
Yageo
RC0805FR-077K87L
23
1
R10
1.24Ω, 1%, 1/4W chip resistor
SMD1206
Yageo
RC1206FR-071R24L
24
1
R12
16.2kΩ, 1%, 1/8W chip resistor
SMD0805
Yageo
RC0805FR-0716K2L
25
1
R13
8.66kΩ, 1%, 1/8W chip resistor
SMD0805
Yageo
RC0805FR-078K66L
26
1
R14
0.0Ω, 1/8W chip resistor
SMD0805
Panasonic
ERJ-6GEY0R00V
27
1
U1
Switchmode LED Driver
with High Current Accuracy
SO-16
Supertex
HV9912NG
2.2nF, 5%, 50V C0G ceramic chip
capacitor
6.8nF, 5%, 50V C0G ceramic chip
capacitor
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-HV9912DB1
A032913
6
1235 Bordeaux Drive, Sunnyvale, CA 94089
Tel: 408-222-8888
www.supertex.com