MIC4833YML Evaluation Board User Guide

MIC4833 Evaluation Board
Low Noise Dual 220 VPP EL Driver
With Output Voltage Slew Rate Control
General Description
The MIC4833 is a low noise dual Electroluminescent
(EL) Panel driver used in backlighting applications.
The MIC4833 converts a low DC voltage to a high
DC voltage using a boost converter and then
alternates the high DC voltage across the EL panels
using an H-bridge. The MIC4833 incorporates
internal wave-shaping circuitry specifically designed
to reduce audible noise emitted by EL panels. The
two EL panels may be dimmed by applying a PWM
signal to the device.
An external resistor may be used to adjust the
output voltage slew rate to reduce audible noise.
The MIC4833 features separate oscillators for the
boost and H-bridge stages to allow independent
control. External resistors set the operating
frequencies of each stage allowing the EL circuit to
optimize efficiency and brightness.
Requirements
The MIC4833 evaluation board requires an input
power source that is able to deliver greater than
400mA at 2.3V.
Precautions
The evaluation board does not have reverse polarity
protection. Applying a negative voltage to the VIN
terminal may damage the device. The MIC4833 is a
high voltage, low current device and should be
handled with care.
Getting Started
1. Connect an external supply to VIN. Apply
desired input voltage to the VIN (J1) and
ground terminal (J2) of the evaluation board,
paying careful attention to polarity and
supply voltage (2.3V ≤ VIN ≤ 5.8V). An
ammeter may be placed between the input
supply and the VIN terminal to the evaluation
board. Ensure that the supply voltage is
monitored at the VIN terminal. The ammeter
and/or power lead resistance can reduce the
voltage supplied to the input.
between the ELB (J4) and COM (J5)
terminals if desired. Note that polarity of the
EL panel does not matter.
3. Enable/Disable the MIC4833 Boost
Regulator. JP3 is the enable/disable jumper
for the Boost Regulator portion of the
MIC4833.
Connecting
JP3-to-ground
disables the boost regulator and connecting
JP3 to VIN enables the boost regulator. A
voltage signal may be applied to the center
pin of JP3 to enable or disable the boost
regulator. A low voltage signal (0V) will
disable the boost regulator, while a high
voltage equal to VIN will enable the boost
regulator. The enable voltage should rise
and fall between high and low monotonically
without interruptions.
4. Enable/Disable the MIC4833 H-Bridge.
JP4 is the enable/disable jumper for the HBridge portion of the MIC4833. Connecting
JP4 to ground disables the H-Bridge and
connecting JP4 to VIN enables the H-Bridge.
Disabling the H-Bridge does not disable the
boost regulator.
5. Enable/Disable the EL Panel Individually.
Both the Boost Regulator and the H-Bridge
of the MIC4833 must be enabled in order for
the EL panel to illuminate. Remove the ENA
(JP1) and ENB (JP2) jumpers to disable EL
Panel A and Panel B, respectively. For
minimum shutdown current, both the Boost
Regulator and the H-Bridge should be
turned off as well.
Ordering Information
Part Number
MIC4833YML EV
Description
220Vpp EL Driver, 3mm x 3mm
MLF® Evaluation Board
2. Connect EL panel(s). Connect one EL
panel between the ELA (J3) and COM (J5)
terminals. Connect another EL panel
MLF and MicroLeadFrame are a registered trademark of Amkor Technology.
Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax 1 (408) 474-1000 • http://www.micrel.com
M9999-043009
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MIC4833 Evaluation Board
Pulling ENA or ENB high (above 1.2V) or low (below
0.4V) will turn ELA and ELB panels on or off.
PWM Dimming
The MIC4833 may be dimmed by adding a shunt
capacitor (CPWM) to the REL pin, shown in Figure 1.
The duty cycle of the PWM signal changes the
frequency of the EL panel, thereby changing its
brightness. Increasing the PWM duty cycle increases
the EL frequency to a maximum set by R2 (Duty
Cycle = 100%). Decreasing the PWM duty cycle
decreases the EL frequency. The PWM duty cycle
should not be lowered to a level that may cause the
EL frequency to be lower than 100Hz, since EL
frequencies lower than 100Hz may cause the panel to
flicker. The frequency of the PWM signal can range
from 500Hz to 50kHz. The peak voltage of the PWM
signal should be equal to VDD. The evaluation board
does not provide a footprint to add this capacitor.
Boost Regulator Output Voltage
The boost regulator output voltage is set to 110V.
The output peak-to-peak voltage across the EL panel
is approximately two times the boost regulator output
voltage (220VPP).
Switching Frequency
The switching frequency of the converter is controlled
by an external resistor (R1) connected between RSW
and VDD. The switching frequency increases as the
resistor value decreases. In general, the lower the
switching frequency, the greater the input current is
drawn to deliver more power to the output. Lower
switching frequencies can be used to drive larger
panels. However, the switching frequency should not
be so low as to allow the voltage at the switch node or
the CS pin to exceed the absolute maximum voltage
of those pins. For resistor value selections, see Table
2 on Page 3 or use the equation below. The switching
frequency range is 35kHz to 350kHz, with an
accuracy of ±20%.
R2
VDD
f SW (kHz) =
46
R1 (MΩ )
PWM
1kHz
EL Frequency
The EL panel frequency is controlled by an external
resistor (R2) connected between REL and VDD pin.
The panel frequency increases as the resistor value
decreases. In general, as the EL panel frequency
increases, the amount of current drawn from the
battery will increase. The EL panel brightness is
dependent upon its frequency. For resistor value
selections, see Table 2 on page 3 or use the equation
below. The EL panel frequency range is 100Hz to
1500Hz, with an accuracy of ±20%.
( )
fEL Hz =
CPWM
0.01µF
Figure 1. PWM Dimming Circuit
Slew Resistor
The MIC4833 is designed to reduce audible noise in
EL panels by the use of the internal wave-shaping
circuit. To further reduce audible noise, a Slew
Resistor (R5) can be added to limit the rate of change
of the EL driver output voltage by limiting the output
current. A slower rate of change in voltage across the
EL panel creates less physical distortion in the
material and therefore reduces the amount of audible
noise. The lower the ISLEW, the slower the output
voltage will change across the EL panels. If R5 is not
used, the ISLEW is by default 5mA, equivalent to using
a 22kΩ for RSLEW.
425
( )
R2 MΩ
Enable Function
There are a few different ways to enable and disable
the MIC4833. The R1 resistor can be pulled to VDD
or ground to enable or disable the boost regulator,
respectively. This turns off both the EL panels by
cutting power to the device completely. If R1 is not
pulled all the way to VDD, then the frequency set by
R1 will be different than the programmed value.
Similarly, the R2 resistor can be pulled to VDD or
ground to enable or disable the H-bridge. It must also
be pulled all the way to VDD so that the EL frequency
is equal to its programmed value.
For individual panel control, the ENA and ENB pins
can be used to enable ELA and ELB, respectively.
April 2009
RE L pin
0V
R5
ISLEW
Open
5mA
125kΩ
1mA
22kΩ
5mA
10kΩ
10mA
Table 1. Slew Resistor Setting
2
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MIC4833 Evaluation Board
Evaluation Board Schematic
U1
MIC4833YML
VIN
J1
+VIN
2.3V to 5.8V
1
JP1
2
R3
10K
2
JP3
ENA
SLEW
12
2
VDD
ELA
11
VIN
C1
0.01µF
10V
R1
332k
1
1
ELB
3
RSW
3
R2
1.78M
1
2
JP4
R5
10k
(optional)
4
REL
5
ENB
10
COM
9
CS
8
SW
7
J3
ELA
EL
LAMP1
J4
ELB
EL2
LAMP2
J5
COM
3
VIN
1
JP2
2
R4
10k
J2
GND
6
GND
VIN
D1
BAS20-V
C3
0.0022µF/250V
L1
220µH
C2
10µF/6.3V
Figure 2: Typical Li-Ion Powered MIC4833 Circuit
Note: Table 2 applies to circuit shown in Figure 2.
Total
Panel
Area
2
(inch )
Capacitance
(nF)
0.4
2
1
5
2
10
3
15
4
20
5
25
6
30
8
40
Panel
Frequency
(Hz)
R2 (MΩ)
R1 (kΩ)
fSW (kHz)
R1 (kΩ)
fSW (kHz)
R1 (kΩ)
fSW (kHz)
R1 (kΩ)
fSW (kHz)
R1 (kΩ)
fSW (kHz)
R1 (kΩ)
fSW (kHz)
R1 (kΩ)
fSW (kHz)
R1 (kΩ)
fSW (kHz)
150
200
250
300
350
400
500
2.80
324
138
357
125
402
112
464
98
523
86
619
72
698
65
1000
45
2.10
340
132
365
122
453
100
511
88
665
68
825
55
953
47
1.69
357
126
392
116
487
92
590
77
750
60
909
50
1000
45
1.40
383
118
422
108
549
83
698
65
909
50
1000
45
1.21
392
116
442
102
590
76
768
58
1000
45
1.05
402
112
475
95
649
70
909
50
1000
45
.850
442
102
511
88
681
66
1000
45
Table 2: Recommended R1 & R2 Values for Various Total Panel Sizes
April 2009
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MIC4833 Evaluation Board
Bill of Materials
Item
Part Number
C1
C1608X7R1A103K
Manufacturer
Description
Qty
TDK
(1)
0.01µF Ceramic Capacitor, 10V, X7R, Size 0603
TDK
(1)
1
C2
C1608X5R0J106K
10 µF Ceramic Capacitor, 6.3V, X5R, Size 0603
1
C3
C2012C0G2E2222J
TDK(1)
0.0022µF Ceramic Capacitor, 250V, C0G, Size 0805
1
L1
VLS4012T-221M
TDK(1)
D1
BAS20-V-GS18
R1
CRCW06033323FKEYE3
220µH, 210mA ISAT. (4mmx4mmx1.2mm)
1
(2)
200V/200mA Hi-Voltage Switching Diode
1
(2)
332kΩ, 1%, 1/16W, Size 0603
1
Vishay
Vishay
(2)
R2
CRCW06031784FKEYE3
Vishay
1.78MΩ, 1%, 1/16W, Size 0603
1
R3, R4
CRCW06031002FKEYE3
Vishay(2)
10kΩ, 1%, 1/16W, Size 0603
2
R5
Optional
U1
MIC4833YML
Micrel(3)
Low Noise 12-pin 3mm x 3mm MLF
®
Dual 220Vpp EL Driver with Output Slew Control
1
Notes:
1.
TDK: www.tdk.com
2.
Vishay: www.vishay.com
3.
Micrel, Inc.: www.micrel.com
April 2009
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M9999-043009
(408) 944-0800
Micrel, Inc
MIC4833 Evaluation Board
Printed Circuit Board Layout
Top Layer
Bottom Layer
April 2009
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M9999-043009
(408) 944-0800
Micrel, Inc
MIC4833 Evaluation Board
MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA
TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com
The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for
its use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer.
Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a
product can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for
surgical implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant
injury to the user. A Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk
and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale.
© 2007 Micrel, Incorporated.
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