MIC2860-2DYD6 [MICROCHIP]
LED DISPLAY DRIVER, PDSO6;
| 型号： | MIC2860-2DYD6 |
| 厂家： | 
MICROCHIP |
| 描述： | LED DISPLAY DRIVER, PDSO6 驱动 光电二极管 接口集成电路 |
| 文件： | 总12页 (文件大小：360K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MIC2860-D
High Efficiency 2 Channel WLED Driver
with Single Wire Digital Control
General Description
Features
The MIC2860-2D is a high efficiency White LED (WLED)
driver designed to drive two WLEDs and greatly extend
battery life for portable display backlighting, and keypad
backlighting in low cost mobile devices. The MIC2860-2D
architecture provides the highest possible efficiency by
eliminating switching losses present in traditional charge
pumps or inductive boost circuits. It features a typical
dropout of 52mV at 30.2mA per channel. This allows the
WLEDs to be driven directly from the battery eliminating
switching noise and losses present with the use of boost
circuitry.
• High Efficiency (no switching losses)
• No charge pumps
• 2 WLED driver channels
• Single wire digital control
• Input voltage range: 3.0V to 5.5V
• WLED driver dropout of 52mV at 30.2mA
• Matching better than ±0.5% (typical)
• Current Accuracy better than ±1.0% (typical)
• Available in Thin SOT-23 and SC-70 6 pin packages
The two channels have better than ±0.5% matching, which
ensures uniform display illumination under all conditions.
The WLEDs brightness is externally preset by a resistor
and dimmed using a single wire digital control signal. The
MIC2860-2D single wire digital interface accepts digital
programming pulses providing 32 dimming steps.
Applications
• Mobile handsets
• Digital cameras
• Portable media/MP3 players
• Portable navigation devices (GPS)
• Portable applications
The MIC2860-2D is available in Thin SOT-23 and SC-70
six pin packages with a junction temperature range of
-40°C to +125°C.
Datasheets and support documentation can be found on
Micrel’s web site at: www.micrel.com.
____________________________________________________________________________________________________________
Typical Application
LCD Display Backlight with 2 WLEDs
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
M9999-072010-A
July 2010
Micrel Inc.
MIC2860-2D
Ordering Information
Part Number
Mark Code(1)
Temperature Range
Package(2)
MIC2860-2DYC6
MIC2860-2DYD6
62D
–40°C to +85°C
–40°C to +85°C
6-Pin SC-70
602D
6-Pin Thin SOT-23
Note:
1. Under bar symbol ( _ ) may not be to scale.
2. Package is GREEN RoHS compliant. Lead finish is NiPdAu. Mold compound is halogen free.
Pin Configuration
6-Pin SC-70 (C6)
(Top View)
6-Pin Thin SOT-23 (D6)
(Top View)
Pin Description
Pin Number
Pin Name
Pin Function
MIC2860-2D
1
2
3
4
5
SC
GND
VIN
Serial Control Digital input. Do not leave floating.
Ground.
Voltage Input. Connect at least 1µF ceramic capacitor between VIN and GND.
LED2 driver. Connect LED anode to VIN and cathode to this pin. Do not leave floating.(1)
D2
RSET
Connect an external resistor from this pin to GND to set the maximum LED current. Example,
apply a 9.53kΩ resistor between RSET and GND to set LED current to 30mA at 100% duty
cycle.
6
D1
LED1 driver. Connect LED anode to VIN and cathode to this pin. Do not leave floating. (1)
Note 1. When driving only 1 LED, connect D1 and D2 in parallel to the LED cathode and adjust the RSET resistor for half the desired output.
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Micrel Inc.
MIC2860-2D
Absolute Maximum Ratings(1)
Operating Ratings(2)
Main Input Voltage (VIN)...................................-0.3V to +6V
Enable Input Voltage (VSC).................................-0.3V to VIN
LED Driver Voltage (VD1, D2) ..............................-0.3V to VIN
Power Dissipation .....................................Internally Limited
Lead Temperature (soldering, 10sec.)....................... 260°C
Storage Temperature (Ts) ..........................-65°C to +150°C
ESD Rating(3)................................................. ESD Sensitive
Supply Voltage (VIN)..................................... +3.0V to +5.5V
Enable Input Voltage (VSC) .................................... 0V to VIN
LED Driver Voltage (VD1, D2) .................................. 0V to VIN
Junction Temperature (TJ) ........................–40°C to +125°C
Junction Thermal Resistance
SC-70 (θJA).....................................................256 °C /W
SOT-23 (θJA)..................................................177 °C /W
Electrical Characteristics
VIN = VSC = 3.6V, CIN = 1µF, RSET = 9.53kΩ; VD1, D2 = 0.6V; TJ = 25°C, bold values indicate –40°C ≤ TJ ≤ 85°C; unless
noted.
Parameter
Conditions
Min
Typ
30.2
±0.5
Max
33.22
±3
Units
mA
%
Current Accuracy(4)
Matching(5)
27.18
Drop-out (VD1, D2
)
Where ILED = 90% of LED current seen at
52
125
mV
V
DROPNOM = 0.6V, 100% brightness level
IOUT = 30.2mA
SC = 0V > 500µs
Ground/Supply Bias Current
0.7
1.5
mA
µA
Shutdown Current
V
0.01
1
(current source leakage)
Digital Dimming
VSC Input Voltage
Logic Low
0.4
V
V
Logic High
1.4
0.3
VSC Enable Input Current
tSHUTDOWN
VSC = 1.2V
0.01
100
1
µA
µs
µs
µs
Time SC pin is low to put into shutdown
Time for valid SC edge; Ignored if outside limit range
Delay from SC is high to start up
500
75
tPROG_HIGH, tPROG_LOW
tSTART_UP
33
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. As determined by average current of all channels in use and all channels loaded.
5. The current through each LED meets the stated limits from the average current of all LEDs.
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Micrel Inc.
MIC2860-2D
Typical Characteristics
Dropout Voltage
Peak LED Current
vs. RSET
Dropout Voltage
vs. Brightness Level
vs. RSET
70
125
100
75
50
25
0
35
30
25
20
15
10
5
60
50
40
LED1
LED2
30
LED2
20
LED1
10
0
RSET = 9.53kꢀ
20 25 30
0
8
12
16
20
24
28
32
0
5
10
15
35
5
10
15
20
25
30
35
R
SET (kΩ)
BRIGHTNESS LEVEL
R
SET (kΩ)
Dropout Voltage
vs. Temperature
Matching
vs. Temperature
100
80
60
40
20
0
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00
RSET = 9.53kꢀ
BL-21
BL-31
BL-31
BL-21
BL-11
BL-0
BL-11
RSET = 9.53kꢀ
20 40 60 80 100 120
-40 -20
0
20 40 60 80 100 120
-40 -20
0
TEMPERATURE (°C)
TEMPERATURE (°C)
LED Current
LED Current
LED Current
vs. Temperature
vs. Temperature
vs.Temperature
22.0
21.5
21.0
20.5
20.0
19.5
19.0
18.5
18.0
11.0
10.9
10.8
10.7
10.6
10.5
10.4
10.3
10.2
10.1
10.0
32.0
31.5
31.0
30.5
30.0
29.5
29.0
28.5
28.0
LED1-BL21
LED1-BL31
LED2-BL31
LED2-BL11
LED1-BL11
LED2-BL21
RSET = 9.53kꢀ
RSET = 9.53kꢀ
20 40 60 80 100 120
RSET = 9.53kꢀ
-40 -20
0
20 40 60 80 100 120
-40 -20
0
20
40
60
80 100
-40 -20
0
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
Note: BL = Brightness Level
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Micrel Inc.
MIC2860-2D
Functional Characteristics
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Micrel Inc.
MIC2860-2D
Functional Diagram
Figure 1. MIC2860-2D Functional Block Diagram
RSET
Functional Description
The RSET pin is used by connecting an RSET resistor to
ground to set the peak current of the linear drivers. The
maximum LED current set by the RSET resistor is shown
in the table below:
The MIC2860-2D is a 2 channel WLED driver. The
WLED driver is designed to maintain proper current
regulation with LED current accuracy of 1.0% while the
typical matching between the 2 channels is 0.5% at
room temperature. The WLEDs are driven independently
from the input supply and will maintain regulation with a
dropout of 52mV at 30.2mA. The low dropout of the
linear drivers allows the WLEDs to be driven directly
from the battery voltage and eliminates the need for
large and inefficient charge pumps. The maximum
WLED current for each channel is set via an external
resistor.
RSET (kꢀ)
9.53
ILED (mA)
30.2
11.5
25.0
14.3
20.1
15.8
18.2
19.1
15.1
28.7
10.0
Block Diagram
As shown in Figure 1, the MIC2860-2D consists of 2
current mirrors set to copy a master current determined
by RSET. The linear drivers have a designated control
block for enabling and dimming of the WLEDs. The
MIC2860-2D dimming is controlled by an internal Digital
Control Interface.
Table 1. Maximum LED Current vs. RSET Resistor Values
A plot of maximum ILED versus RSET is shown in Figure 2.
Peak LED Current
vs. RSET
VIN
35
The input supply (VIN) provides power to the linear
drivers and the control circuitry. The VIN operating range
is 3V to 5.5V. Due to wire inductance a minimum bypass
capacitor of 1µF should be placed close to the input (VIN)
pin and the ground (GND) pin. Refer to the layout
recommendations section for details on placing the input
capacitor (C1).
30
25
20
15
10
5
0
SC
8
12
16
20
24
28
32
The SC pin is equivalent to the enable pin for the linear
drivers on the MIC2860-2D. It can also be used for
dimming using a single wire digital interface. See the
MIC2860-2D Digital Dimming Interface in the Application
Information section for details. Do not leave control pins
floating.
RSET (kꢀ)
Figure 2. Peak LED current vs. RSET
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Micrel Inc.
MIC2860-2D
D1, D2
GND
The D1 and D2 pins are the linear driver inputs for
WLED 1 and 2 respectively. Connect the anodes of the
WLEDs to VIN and each cathode of the WLEDs to D1
and D2. When operating with a single WLED, D1 and D2
should be connected to the WLED cathode to parallel
the outputs for improved dropout performance.
Paralleling these pins can also be done to drive a higher
current through a single WLED. Do not leave these pins
floating
The ground pin is the ground path for the linear drivers.
The current loop for the ground should be as small as
possible. The ground of the input capacitor should be
routed with low impedance traces to the GND pin and
made as short as possible. Refer to the layout
recommendations for more details.
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Micrel Inc.
MIC2860-2D
Application Information
Digital Dimming Interface
Brightness levels are linearly spaced with a maximum
current equal to 100% of the current set by RSET. The
MIC2860-2D is designed to receive programming pulses
to decrease brightness from the initial start up default
(level 1 maximum current). Once the brightness change
signal is received, the SC pin is simply pulled high to
maintain the brightness. This “set and forget” feature
relieves processor computing power by eliminating the
need to constantly send a PWM signal to the dimming
pin.
Brightness
ILED (mA)
ILED (mA)
% of Max.
Current
Level (0 - 31)
RSET=14.3kꢀ
RSET=19.1kꢀ
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
20.1
19.4
18.8
18.2
17.5
16.8
16.2
15.6
14.9
14.2
13.6
13.0
12.3
11.6
11.0
10.4
9.7
15.1
14.6
14.1
13.6
13.1
12.6
12.2
11.7
11.2
10.7
10.2
9.7
9.2
8.7
8.3
7.8
7.3
6.8
6.4
5.8
100
96.7
93.7
90.4
87.1
83.8
80.8
77.5
74.2
70.9
67.9
64.6
61.3
57.9
55.0
51.7
48.3
45.0
42.1
38.7
35.4
32.1
29.1
25.8
22.5
19.2
16.2
12.9
9.6
Start Up
Assuming the MIC2860-2D has been off for a long time,
the MIC2860-2D will start-up in its default mode
approximately 33µs (tSTART_UP) after a logic level high is
applied to the SC pin. In the default mode the WLEDs
are turned on at the maximum brightness (level 31).
Each falling edge will cause the default brightness level
to decrease by one.
9.1
8.5
7.8
7.1
6.5
5.9
5.3
4.8
4.4
3.9
3.4
2.9
2.4
1.9
8
5.2
7
4.5
6
3.9
Figure 3. Typical Start-Up Timing
Shutdown
5
3.3
4
2.6
3
1.9
1.4
2
1
0
1.3
0.7
0.3
0.9
0.5
0.2
6.3
3.3
1.7
When the SC input pin is pulled low for a period greater
than or equal to tSHUTDOWN (500µs), the MIC2860-2D will
turn off the current sinks as shown in Figure 4.
Table 2. Digital Interface Brightness Level Table
The MIC2860-2D incorporates an easy to use single
wire, serial programming interface that allows users to
set WLED brightness up to 32 different levels as shown
in Table 2. To calculate the brightness level for other
RSET values, multiply the percentage of max current
values by the maximum LED current set by the RSET
resistor value from table 1.
Figure 4. Shutdown Timing
For example with RSET = 19.1kꢀ, the max current
(brightness level = 31) is 15.1mA and brightness level 20
would equate to 15.1mA x 0.646 = 9.7mA.
Once the device is shutdown, the control circuit supply is
disabled and the WLEDs are turned off drawing only
0.01µA. Brightness level information stored in the
MIC2860-2D prior to shutdown will be erased and upon
a following startup signal the WLEDs will be turned on at
maximum brightness (level 31).
Programming the Brightness Level
MIC2860-2D is designed to start driving the WLEDs
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Micrel Inc.
MIC2860-2D
33µs (tSTART_UP) after the SC pin is first pulled high at the
maximum brightness level 1. After start up, the internal
control logic is ready to decrease the WLED brightness
upon receiving programming pulses (positive edges
applied to SC pin). The brightness level can be
decreased one level by applying a single programming
pulse as shown in Figure 5. Brightness settings can be
quickly changed by sending programming pulses one
after each other. Each programming pulse has a high
(tPROG_HIGH) and a low (tPROG_LOW) pulse width that must
be between 0.3µs to 75µs.
Counter Roll-Over
The MIC2860-2D internal counter contains registers
from 0 to 31 (32 levels). When the brightness level is at
32 (minimum brightness) and a programming pulse
forces the brightness to step down, the counter will roll-
over to level 31 (maximum brightness). This is illustrated
in Figure 7.
Figure 7. Down Counter Roll-Over
Input Capacitor
Figure 5. Brightness Programming Pulses
The MIC2860-2D is a high performance, high bandwidth
device. Stability can be maintained using a ceramic input
capacitor of 1µF. Low ESR ceramic capacitors provide
optimal performance at a minimum amount of space.
Additional high-frequency capacitors, such as small
valued NPO dielectric type capacitors, help filter out high
frequency noise and are good practice in any noise
sensitive circuit. X5R or X7R dielectrics are
recommended for the input capacitor. Y5V dielectrics
lose most of their capacitance over temperature and are
therefore not recommended.
Multiple brightness levels can be changed as shown in
Figure 6. When issuing multiple brightness level
adjustments to the SC pin, ensure both tPROG_LOW and
tPROG_HIGH are within 0.3µs and 75µs.
To maintain operation at the current brightness level
simply maintain a logic level high at the SC pin.
Figure 6. Consecutive Brightness Level Commands
The MIC2860-2D can be programmed to set WLED
drive current to produce one of 32 distinct brightness
levels. The following section explains how the brightness
counter functions with continued programming edges.
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Micrel Inc.
MIC2860-2D
MIC2860-2D Typical Application Circuit
Bill of Materials
Item
C1
Part Number
Manufacturer
TDK(1)
Vishay(2)
Micrel, Inc.(3)
Description
Qty.
C1608X5R0J105K
CRCW06032052FT1
MIC2860-2DYC6
1µF Ceramic Capacitor, 6.3V, X5R, Size 0603
9.53kꢀ, 1%, Size 0603
1
1
1
R1
U1
2 Channel Digital Control Linear WLED Driver
Notes:
1. TDK: www.tdk.com
2. Vishay: www.vishay.com
3. Micrel, Inc.: www.micrel.com
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Micrel Inc.
MIC2860-2D
Package Information
6-Pin SC-70 (C6)
6-Pin Thin SOT-23 (D6)
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July 2010
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Micrel Inc.
MIC2860-2D
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 at Purchaser’s own risk and Purchaser agrees to
fully indemnify Micrel for any damages resulting from such use or sale.
© 2010 Micrel, Incorporated.
M9999-072010-A
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