View MIC2860-2PYC6_5057525.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

MIC2860-P
High Efficiency 2 Channel WLED Driver with PWM Control
General Description
The MIC2860-2P 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 MIC2860-2P 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. The two channels have typical matching of 0.5%, which ensures uniform display illumination under all conditions. The WLEDs brightness is externally preset by a resistor and dimmed using PWM interface operating down to less than 1% duty cycle. The MIC2860-2P is available in Thin SOT-23 and SC-70 six pin packages with a junction temperature range of -40C to +125C. Datasheets and support documentation can be found on Micrel's web site at: www.micrel.com.
Features
* * * * * * * High efficiency (no switching losses) PWM frequency as low as 250Hz Input voltage range: 3.0V to 5.5V Linear 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 packages
Applications
* Mobile handsets * Digital cameras * Portable media/MP3 players * Portable navigation devices (GPS) * Portable applications
____________________________________________________________________________________________________________
Typical Application
LCD Display Backlight with 2 WLEDs
MLF and MicroLeadFrame are registered trademark Amkor Technology Inc. Micrel Inc. * 2180 Fortune Drive * San Jose, CA 95131 * USA * tel +1 (408) 944-0800 * fax + 1 (408) 474-1000 * http://www.micrel.com
September 2010
M9999-092710-A
Micrel Inc.
MIC2860-2P
Ordering Information
Part Number MIC2860-2PYC6 MIC2860-2PYD6
Notes: 1. Under bar symbol ( _ ) may not be to scale. 2. Package is GREEN RoHS compliant. Lead finish is NiPdAu. Mold compound is halogen free.
Mark Code(1) 62P 602P
Junction Temperature Range -40C to +125C -40C to +125C
Package(2) 6-Pin SC-70 6-Pin Thin SOT-23
Pin Configuration
6-Pin SC-70 (C6) (Top View)
6-Pin Thin SOT-23 (D6) (Top View)
Pin Description
Pin Number MIC2860-2P 1 2 3 4 5 6 Pin Name EN GND VIN D2 RSET D1 Pin Function PWM Control Pin. This pin is used as a PWM input for dimming of WLEDs. Do not leave floating. Ground. Voltage Input. Connect at least 1F ceramic capacitor between VIN and GND. LED2 driver. Connect LED anode to VIN and cathode to this pin. Do not leave floating. An internal 1.27V reference sets the nominal maximum WLED current. Example, apply a 9.53k resistor between RSET and GND to set LED current to 30.2mA at 100% duty cycle. LED1 driver. Connect LED anode to VIN and cathode to this pin. Do not leave floating.
September 2010
2
M9999-092710-A
Micrel Inc.
MIC2860-2P
Absolute Maximum Ratings(1)
Main Input Voltage (VIN) .................................. -0.3V to +6V Enable Input Voltage (VEN)................................ -0.3V to VIN LED Driver Voltage (VD1, D2) ............................. -0.3V to VIN Power Dissipation .....................................Internally Limited Lead Temperature (soldering, 10sec.)....................... 260C Storage Temperature (Ts) .........................-65C to +150C ESD Rating.................................................................... 2KV
Operating Ratings(2)
Supply Voltage (VIN)..................................... +3.0V to +5.5V Enable Input Voltage (VEN) .................................... 0V to VIN LED Driver Voltage (VD1, D2) .................................. 0V to VIN Junction Temperature (TJ) ........................ -40C to +125C Junction Thermal Resistance SC-70 (JA).....................................................256 C /W SOT-23 (JA) ..................................................177 C /W
Electrical Characteristics
WLED Linear Drivers
VIN = VEN = 3.6V, CIN = 1F, RSET = 9.53k; VD1, D2 = 0.6V; TJ = 25C, bold values indicate -40C TJ 85C; unless noted. Parameter Current Accuracy Matching
(4) (3)
Conditions
Min. 27.18
Typ. 30.2 0.5
Max. 33.22 3 125 1.5 1 0.4
Units mA % mV mA A V V A s
Drop-Out (VD1,D2) Ground/Supply Bias Current Shutdown Current (current source leakage) PWM Dimming Enable Input Voltage (VEN) Enable Input Current Current-Source Delay (50% levels)
Where ILED = 90% of LED current seen at VDROPNOM = 0.6V, 100% brightness level IOUT = 30.2mA VEN = 0V Logic Low Logic High VEN 1.4 Shutdown to On Standby to On On to Standby TRISE TFALL VEN = 0V 4 1.4
52 0.7 0.01
0.01 32 1.5 0.3 0.7 0.2 5.8
1 80 4
Current-Source Transient Time (10%-90%) On-to-Shutdown Time
Notes: 1. 2. 3. 4.
s 10 ms
Exceeding the absolute maximum rating may damage the device. The device is not guaranteed to function outside its operating rating. As determined by average current of all channels in use and all channels loaded. The current through each LED meets the stated limits from the average current of all LEDs.
September 2010
3
M9999-092710-A
Micrel Inc.
MIC2860-2P
Typical Characteristics
Peak LED Current vs. RSET
CURRENT SINK DROPOUT (mV)
35 30
70 60 50 40
Dropout Voltage vs. RSET
70 60
Dropout Voltage vs. Temperature
LED CURRENT (mA)
25 20 15 10 5 0 5 10 15 20 25 30 35
LED DROPOUT (mV)
LED1
50 40
LED1 30 20 10 0 0 10 20 30 40 LED2
LED2
30 20 10 0 -40 -20 0 20 40 60 80 100 120
RSET = 9.53K
RSET (K)
RSET (K)
TEMPERATURE (C)
Dropout Voltage vs. Temperature
35 30
LED Current vs. Temperature
32 31.5
16 15.5 15 14.5 14 13.5
LED Current vs.Temperature
LED CURRENT (mA)
LED DROPOUT (mV)
LED CURRENT (mA)
LED2
25 20 15 10 5 0 -40 -20 0 20 40 60 80 100 120
31 30.5 30 29.5 29 28.5 28 -40 -20 0 20 40 60 80 100 120
ILED1 ILED2
LED1
LED1
LED2
RSET = 19.1K
RSET = 9.53K
13 -40 -20 0 20 40
RSET = 19.1K
60 80 100 120
TEMPERATURE (C)
TEMPERATURE (C)
TEMPERATURE (C)
Matching vs. Temperature
0.4 0.35 0.3
MATCHING (%)
0.25 0.2 0.15 0.1 0.05 0 -40 -20 0 20 40 60 80 100 120
RSET = 9.53K
RSET = 19.1K
TEMPERATURE (C)
September 2010
4
M9999-092710-A
Micrel Inc.
MIC2860-2P
Functional Characteristics
September 2010
5
M9999-092710-A
Micrel Inc.
MIC2860-2P
Functional Characteristics (Continued)
September 2010
6
M9999-092710-A
Micrel Inc.
MIC2860-2P
Functional Diagram
Figure 1. MIC2860-2P Functional Block Diagram
September 2010
7
M9999-092710-A
Micrel Inc.
MIC2860-2P
Functional Description
The MIC2860-2P is a two channel WLED driver. The WLED driver is designed to maintain proper current regulation with LED current accuracy of 1% with a typical matching between the 2 channels of 0.5%. 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 peak WLED current for each channel is set via an external resistor. If dimming is desired the MIC2860-2P can dim via a PWM signal. Block Diagram As shown in Figure 1, the MIC2860-2P consists of two current sinks with the peak current determined by RSET. The linear drivers have a designated control block for enabling and dimming of the WLEDs. The MIC2860-2P is controlled by the PWM control block that receives PWM signals for dimming. VIN 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 1F should be placed close to input (VIN) pin and the ground (GND) pin. EN The EN pin enables the linear drivers. It can also be used for dimming with a PWM signal. See the PWM Dimming Interface in the Application Information section for details. Do not leave floating. RSET The RSET pin is used by connecting a RSET resistor to ground to set the peak current of the linear drivers. The maximum LED current (EN = 100% Duty Cycle) set by the RSET resistor is shown in the table below: RSET (k) 9.53 11.5 14.3 15.8 19.1 28.7 ILED (mA) 30.2 25.0 20.1 18.2 15.1 10.0
35 30 LED CURRENT (mA) 25 20 15 10 5 0 8
Peak LED Current vs. RSET
12
16
20 RSET (k)
24
28
32
Figure 2. Peak LED Current vs. RSET
D1, D2 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. GND 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.
Table 1. Maximum LED Current vs. RSET Resistor Values
A plot of ILED versus RSET is shown in Figure 2.
September 2010
8
M9999-092710-A
Micrel Inc.
MIC2860-2P Input Capacitor The MIC2860-2P is a high performance, high bandwidth device. Stability can be maintained using a ceramic input capacitor of 1F. Low-ESR ceramic capacitors provide optimal performance with 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 noisesensitive 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.
Application Information
PWM Dimming Interface The MIC2860-2P can receive PWM signals from the EN pin for WLED dimming. Dimming is generated by pulsing the WLEDs on and off in synchronization with the PWM signal. The MIC2860-2P incorporates an internal shutdown delay to ensure that the internal control circuitry remains active during PWM dimming for optimum performance. The lower PWM frequency range is recommended at 250Hz due to the minimum standby to shutdown time of 4ms. As the period of 250Hz is 4ms, a 1% duty cycle would have an on time of 40us and an off time of 3.96ms. To support operation down to 1% duty cycle, the maximum off time must not exceed 4ms or the drivers may go into the low Iq shutdown state. With PWM frequencies higher than 500Hz the TRISE (0.7s) and TFall (0.2s) times will have a greater effect on the accuracy of the outputs. An upper frequency of 500Hz is recommended to maintain output accuracy with duty cycles down to 1%. For systems that do not require a duty cycle below 1%, the frequency of the PWM signal may be increased. For example, with a minimum duty cycle of 10% (3.02mA with RSET = 9.53k) the PWM frequency can be increased to 10kHz and still maintain accuracy.
September 2010
9
M9999-092710-A
Micrel Inc.
MIC2860-2P
MIC2860-2P Typical Application Circuit
Bill of Materials
Item C1 R1 U1
Notes: 1. 2. 3. TDK: www.tdk.com. Vishay: www.vishay.com. Micrel, Inc.: www.micrel.com.
Part Number C1608X5R0J105K CRCW06032052FT1 MIC2860-2PYC6 MIC2860-2PYD6
Manufacturer TDK
(1)
Description 1F Ceramic Capacitor, 6.3V, X5R, Size 0603 9.53k, 1%, Size 0603 2-Channel PWM Linear WLED Driver, SC-70 2-Channel PWM Linear WLED Driver, SOT-23
Qty. 1 1 1
Vishay(2) Micrel, Inc.(3)
September 2010
10
M9999-092710-A
Micrel Inc.
MIC2860-2P
Package Information
6-Pin SC-70 (C6)
September 2010
11
M9999-092710-A
Micrel Inc.
MIC2860-2P
Package Information (Continued)
6-Pin Thin SOT-23 (D6)
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
Micrel makes no representations or warranties with respect to the accuracy or completeness of the information furnished in this data sheet. This information is not intended as a warranty and Micrel does not assume responsibility for its use. Micrel reserves the right to change circuitry, specifications and descriptions at any time without notice. No license, whether express, implied, arising by estoppel or otherwise, to any intellectual property rights is granted by this document. Except as provided in Micrel's terms and conditions of sale for such products, Micrel assumes no liability whatsoever, and Micrel disclaims any express or implied warranty relating to the sale and/or use of Micrel products including liability or warranties relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right 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. (c) 2010 Micrel, Incorporated.
September 2010
12
M9999-092710-A

▲Up To Search▲

Price & Availability of MIC2860-2PYC6

	To Download MIC2860-2PYC6 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .