MIC4834YMM [MICREL]
Low Noise Dual 220 VPP EL Driver; 低噪声双220 VPP EL驱动器
| 型号： | MIC4834YMM |
| 厂家： | 
MICREL SEMICONDUCTOR |
| 描述： | Low Noise Dual 220 VPP EL Driver |
| 文件： | 总12页 (文件大小：794K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MIC4834
Low Noise Dual 220 VPP EL Driver
General Description
Features
•
Drives two EL panels, up to 3 in2 each at full
brightness
The MIC4834 is a low noise dual Electroluminescent (EL)
Panel driver used in backlighting applications. The
MIC4834 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
MIC4834 incorporates internal wave-shaping circuitry
specifically designed to reduce audible noise emitted by
EL panels. With only one inductor the MIC4834 can drive
two outputs and requires a minimum number of passive
components. It features an operating input voltage range
of 2.3V to 5.8V, making it suitable for 1-cell Li-ion and 2- or
3-cell alkaline/NiCad/NiMH battery applications.
•
•
•
•
•
•
•
220VPP regulated AC output waveform
2.3V to 5.8V DC input voltage
Wave-shaping circuit to reduce audible noise
Adjustable boost converter frequency
Single inductor to power both panels
0.1µA typical shutdown current
Package options
−
−
10-pin 3mmx3mm MLF®
10-pin MSOP
•
–40oC to +125oC junction temperature range
The MIC4834 features separate oscillators for the boost
and H-bridge stages. The boost frequency may be
adjusted with an external resistor to optimize efficiency
and brightness. The H-bridge frequency is internally preset
to 225Hz, to reduce the number of external components
and layout space.
Applications
•
•
•
•
•
•
•
Mobile phones
MP3/portable media players (PMP)
Clocks/ watches
Remote controls
Cordless phones
GPS devices
The MIC4834 is available in 10 pin 3mmx3mm MLF®
package as well as MSOP-10L, and has an operating
junction temperature range of –40°C to +125°C.
PDAs
_________________________________________________________________________________________________
Typical Application
Low Noise Dual EL Driver
MLF and MicroLead Frame are registered trademark of Amkor Technologies
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
M9999-100808-A
October 2008
Micrel
MIC4834
Ordering Information
Part Number
Package
Operating Junction Temp Range
Lead Finish
MIC4834YML 10 pin (3mm x 3mm) MLF®
-40ºC to +125ºC
Pb-free / RoHS-Compliant
MIC4834YMM
10-Pin MSOP
-40ºC to +125ºC
Pb-free / RoHS-Compliant
Pin Configuration
10-Pin MLF® - Top View
10-Pin MSOP – Top View
Pin Description
Pin Number
Pin Name
ENA
Pin Function
1
2
3
EL Panel A Enable Pin: Logic high enables ELA and logic low disables ELA output.
DC Input Supply Voltage: 2.3V to 5.8V
VDD
RSW
RSW pin: Sets internal boost converter switch frequency by connecting an external
resistor (RSW) to VDD. Connecting the RSW resistor to GND shuts down the device.
4
5
6
7
ENB
GND
SW
EL Panel B enable pin: Logic high enables ELB and logic low disables ELB output.
Ground.
Switch Node: Drain of internal high-voltage power MOSFET for boost circuit.
CS
Regulated Boost Output: Connect to the output capacitor of the boost regulator and
to the cathode of the diode.
8
COM
EL output: Common EL output terminal to both ELA and ELB. Connect one end of
each EL panel to this pin.
9
ELB
ELA
EL Panel B output: Connect the other end of the EL panel B to this pin.
EL Panel A output: Connect the other end of the EL panel A to this pin.
Heat Sink Pad. Connect to ground externally. MLF® package only.
10
EPad
HS Pad
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October 2008
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MIC4834
Absolute Maximum Rating(1)
Operating Range(2)
Supply voltage (VDD) ....................................... -0.5V to 6.5V
Output voltage (VCS)...................................... -0.5V to 130V
Switch Node (VSW) ......................................... -0.5V to 130V
Enable Voltage (VRSW, VENA, VENB)................... -0.5V to 6.5V
Ambient Storage Temperature (TS) ...........-65ºC to +150ºC
ESD Rating(3)........................................................................... ESD Sensitive
Supply Voltage (VDD) ........................................2.3V to 5.8V
Switching MOSFET Frequency (fSW)........ 35kHz to 350kHz
Enable Voltage (VRSW, VENA,, VENB) ....................... 0V to VDD
Junction Temperature Range (TJ) ............. -40°C to +125°C
Package Thermal Impedance
3mm x 3mm MLF® (θJA)……………………........ 60°C/W
MSOP (θJA)……………………......................... 206°C/W
Electrical Characteristics(4)
TA = 25oC, VDD= 3.0V unless otherwise noted. Bold values indicate -40°C ≤ TJ ≤ 85°C.
Symbol Parameter
Condition
Min
Typ
Max
Units
VDD
IDD
Supply Voltage Range
2.3
5.8
V
Input Supply Current
VRSW = High; VCS = 105V;
152
220
µA
ELA, ELB, COM = Open
VRSW = Low; VDD = 5.8V
ISW = 100mA, VCS = 105V
VDD = 2.3V to 5.8v
ISD
Shutdown Current
0.1
6.0
109
1
µA
Ω
RDS(ON) On-resistance Of Switching Transistor
12.0
120
VCS
Output voltage Regulation
90
V
VDD = 3.0V
25
35
45
kHz
kHz
kHz
Hz
(RSW = 1.3MΩ )
VDD = 3.0V
fSw
Boost Switching Frequency
75
100
350
225
125
450
285
(RSW = 450kΩ)
V
DD = 3.0V
(RSW = 125kΩ)
DD = 3.0V
ELA, ELB, COM = Open
250
165
V
fEL
ELA, ELB and COM Drive Frequency
D
Switching Transistor Duty Cycle
Output Current Drive Limit
80
95
%
IOUT
2.5
5
7.5
mA
VENA
VENB
,
Enable Logic Threshold
Enable Logic Hysteresis
Enable Input Current
0.4
1.2
150
1
V
VHYS
20
50
mV
µA
IENA
IENB
,
0.1
Notes:
1. Exceeding the absolute maximum rating may damage the device.
2. The device is not guaranteed to function outside its operating rating.
3. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5kΩ in series with 100pF.
4. Specification for packaged product only.
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October 2008
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MIC4834
Typical Characteristics
Switching Frequency
Recommended Switching
Total Input Current
vs SW Resistor
Frequency Vs. Total Lamp Size
vs. Input Voltage
400
140
40
35
30
25
20
15
10
5
fEL = 225Hz
350
300
250
200
150
100
50
120
100
80
60
40
20
0
COUT = 2.2nF
fSW = 94kHz
Size = 2in2
fSW = 116kHz
Size = 1in2
0
0
0
1
2
3
4
5
2
6
2
2.5
3
3.5
4
4.5
5
5.5
6
INPUT VOLTAGE (V)
TOTAL LAMP SIZE (in )
SWITCHING RESISTOR (kOhm)
Total Input Current
vs. Input Voltage
Total Input Current
vs. Input Voltage
CS Voltage
vs. Input Voltage
60
90
85
80
75
70
65
60
55
50
45
40
120
100
80
60
40
20
0
fEL = 225Hz
fEL = 225Hz
55
COUT = 2.2nF
COUT = 2.2nF
50
fSW = 62kHz
fSW = 42kHz
Size = 6in2
45
Size = 4in2
40
35
fSW = 45kHz
EL = 225Hz
COUT = 2.2nF
2.5 3.5
INPUT VOLTAGE (V)
30
fSW = 82kHz
25
fSW = 50kHz
Size = 5in2
f
Size = 3in2
20
2
2.5
3
3.5
4
4.5
5
5.5
6
2 2.5 3 3.5 4 4.5 5 5.5 6
2
3
4 4.5 5 5.5 6
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
Output Voltage
vs. Input Voltage
Brightness
vs. Input Voltage
240
16
14
12
10
8
200
160
120
80
6
Distance = 2 in
fSW = 135kHz
fSW = 45kHz
EL = 225Hz
4
f
fEL = 225Hz
40
2
COUT = 2.2nF
L = 220µH
0
0
2
2.5 3.5
3
4
4.5
5
5.5
6
2
2.5
3
3.5
4
4.5
5
5.5
6
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
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MIC4834
Functional Diagram
Figure 1. MIC4834 Block Diagram
Functional Description
programmed through an external resistor to maximize
efficiency and brightness of the EL panel. The H-bridge
frequency is internally fixed at 225Hz to reduce external
component count.
Overview
The MIC4834 is a high-voltage dual output EL driver with
a peak-to-peak AC output voltage of 220V capable of
driving two 3 in2 EL panels. The MIC4834 drives EL
panels by converting a low DC input voltage to a high
DC high output voltage using the boost regulator circuit
and then alternating the high DC voltage across the EL
panel using an H-Bridge. Input supply current for the
MIC4834 is typically 152µA. The high voltage EL driver
has two internal oscillators to control the boost switching
frequency and the H-bridge driver frequency. The
internal boost oscillator frequency can be individually
Regulation
Referring to Figure 1, power is initially applied to VDD.
When the internal feedback voltage is less than the
reference voltage, the internal comparator enables
switching in the boost circuit. When the boost regulator
is switching, current flows through the inductor into the
switch. The switching MOSFET will typically turn on for
90% of the switching period. During the on-time, energy
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October 2008
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MIC4834
is stored in the inductor. When the switching MOSFET
turns off, current flowing into the inductor forces the
voltage across the inductor to reverse polarity. The
voltage across the inductor rises until the external diode
conducts and clamps the voltage at VOUT + VD1. The
energy in the inductor is then discharged into the COUT
capacitor. The internal comparator continues to turn the
switching MOSFET on and off until the internal feedback
voltage is above the reference voltage. Once the internal
feedback voltage is above the reference voltage, the
internal comparator disables switching. The control
circuit will continue to turn the MOSFET’s on and off to
maintain a constant DC voltage at the CS pin.
ENA or ENB high (over 1.2V) or low (below 0.4V) will
turn ELA and ELB panels on or off.
When the MIC4834 EL Driver is enabled, ELA and ELB
will switch in opposite states with COM to achieve a
220V peak-to-peak AC output signal needed to drive the
two EL panels.
Figure 2. EL Panel Waveform – 2 × 1 in2
Switching Frequency
The switching frequency of the converter is controlled by
an external resistor (RSW) 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. Lowering the switching
frequency 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 the “Typical Characteristics:
Switching Frequency vs. SW Resistor” graph on Page 4
or use the equation below. The switching frequency
range is 35kHz to 350kHz, with an accuracy of ±20%.
Figure 3. EL Panel Waveform – 2 × 2 in2
46
f
(kHz) =
SW
R
(
MΩ
)
SW
EL Frequency
The MIC4834 EL panel frequency is internally fixed at
225Hz.
Enable Function
There are a few different ways to enable and disable the
MIC4834. The boost regulator may be disabled by
pulling the RSW resistor to ground. This turns off both the
EL panels by cutting power to the device completely.
The RSW resistor must be pulled to VDD to enable the
boost oscillator. If it is not equal to VDD, then the
frequency set by RSW will be different the programmed
value.
Figure 4. EL Panel Waveform – 2 × 3 in2
For individual panel control, the ENA and ENB pins can
be used to enable ELA and ELB, respectively. Pulling
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MIC4834
Output Capacitor
Application Information
Low ESR capacitors should be used at the regulated
boost output (CS pin), to minimize the switching output
ripple voltage. The larger the output capacitance, the
lower the output ripple at the CS pin. The reduced
output ripple, at the CS pin, along with a low ESR
capacitor improves the efficiency of the MIC4834 circuit.
Selection of the capacitor value depends upon the peak
inductor current, inductor size, and the load. The
MIC4834 is designed for use with an output capacitance
as low as 2.2nF. For minimum audible noise, the use of
a C0G/NPO dielectric output capacitor is recommended.
TDK and AVX offer C0G/NPO dielectric capacitors in
capacitance up to 2.7nF at 200V to 250V voltage rating
in 0805 size.
The MIC4834 is designed to use an inductance with a
value between 100µH to 330µH. Choosing the right
inductor is always a balance of size, inductance,
efficiency, current rating and cost. A TDK (VLS4012T-
221M) 220µH inductor is recommended based on size,
efficiency and current rating.
Generally, the lower the inductance, the more current
the inductor can handle. Lowering the inductance allows
the boost regulator to draw more input current to deliver
more energy every switching cycle. As a result, a lower
inductance may be used to drive larger panels or
brighten similar sized panels. However, caution is
required as using a low inductance with a low switching
frequency may cause the voltage at the switch node and
the CS pin to exceed the absolute maximum rating. If
the application uses a low input voltage (2.3V to 3V),
then a lower value inductor, such as 100µH, may be
used in order to drive the EL panel at maximum
brightness.
EL Panel Terminals (ELA, ELB, COM)
The two EL panels are connected from ELA to COM and
ELB to COM. The ELA and ELB terminals are in phase
with each other, while the COM is out of phase with both
ELA and ELB. Since ELA and COM are out of phase,
the high voltage generated by the boost regulator is
alternated across ELA and COM by the H-Bridge. The
frequency of each cycle is internally fixed at 225Hz. The
alternating 220V peak-to-peak causes the EL panel to
emit light. Similarly, the ELB and COM are also out of
phase and allows a second EL panel to be driven at the
same time. Both EL panels may operate independently
from each other and do not have to be the same size.
For component selection, Table 2 lists recommended
values for various panel sizes up to a total of 6 in2 (For
example, two 3 in2 panels). Driving overly large panels
will result in a dimmer display, but will not cause damage
to the device.
Diode
The diode must have a high reverse voltage (150V),
since the output voltage at the CS pin can reach up to
130V. A fast switching diode with lower forward voltage
and higher reverse voltage (150V), such as
BAV20WS/BAS20W, can be used to enhance efficiency.
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MIC4834
Application Circuit
Figure 6. Typical Li-Ion Powered MIC4834 Circuit
Note: Table 2 applies to circuit shown in Figure 6.
Total Panel Area (in2) 0.4
1
5
2
3
4
5
6
Capacitance (nF)
RSW (kΩ)
2
10
15
20
25
30
357 392 487 562 750 931 1100
128 116 94 82 62 50 42
fSW (kHz)
Table 2. Recommended RSW Values for Total Panel Sizes
Bill of Materials
Item
C1
C2
C3
L1
Part Number
Manufacturer
TDK(1)
Description
Qty
1
C1608X7R1A103K
C1608X5R0J106K
C2012C0G2E2222J
VLS4012T-221M
BAS20-V-GS18
0.01µF Ceramic Capacitor, 10V, X7R, Size 0603
10 µF Ceramic Capacitor, 6.3V, X5R, Size 0603
0.0022µF Ceramic Capacitor, 250V, C0G, Size 0805
220µH, 210mA ISAT. (4mmx4mmx1.2mm)
TDK(1)
TDK(1)
TDK(1)
Vishay(2)
Vishay(2)
Micrel(3)
1
1
1
D1
200V/200mA Hi-Voltage Switching Diode
1
R1 or RSW CRCW06033323FKEYE3
332kΩ, 1%, 1/16W, Size 0603
1
U1
MIC4834YML
Low Noise Dual 220Vp-p EL Driver with Output Slew Control
1
Notes:
1. TDK: www.tdk.com
2. Vishay: www.vishay.com
3. Micrel, Inc.: www.micrel.com
M9999-100908-A
October 2008
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Micrel
MIC4834
Layout Recommendation (MLF®)
Top Layer
Bottom Layer
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October 2008
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Micrel
MIC4834
Layout Recommendation (MSOP)
Top Layer
Bottom Layer
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Micrel
MIC4834
Package Information
10-Pin 3mm x 3mm MLF® (ML)
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October 2008
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Micrel
MIC4834
10-Pin MSOP (MM)
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.
© 2008 Micrel, Incorporated.
M9999-100908-A
October 2008
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