MIC4832 Evaluation Board Low Noise 220Vp-p EL Driver General Description The MIC4832 is a low audible noise 220Vp-p electroluminescent lamp (EL) driver. Using advanced Bipolar, CMOS, DMOS (BCD) technology, the MIC4832 integrates a high voltage boost converter and an H-bridge driver for driving a large EL lamp. The MIC4832 can drive large panel displays for mobile phones, remote controls, MP3 players or automotive electronics where EL panels are used for backlighting. The MIC4832 offers design flexibility with adjustable lamp and boost converter frequencies, simply by applying external set resistors. Micrel’s new H-Bridge design reduces audible noise by creating smoother AC voltage across the EL panel. The smooth AC voltage waveform eliminates sudden changes in voltage, thus reducing the common cause of audible noise in EL drivers. Requirements The MIC4832 evaluation board requires an input power source that is able to deliver greater than 200mA at 1.8V. Precautions The evaluation board does not have reverse polarity protection. Applying a negative voltage to the VIN terminal may damage the device. The MIC4832 evaluation board is tailored for a Li-Ion range input supply voltage. It should not exceed 5.5V on the input. The MIC4832 is a high voltage, low current device and should be handled with care to prevent a possible electrical buzz. 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 (1.8V ≤ VIN ≤ 5.5V). 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. 2. Connect an EL panel. Connect the EL panel to the VA (J4) and VB (J5) terminals. Note that polarity of the EL panel does not matter. 3. Enable/Disable the MIC4832 Boost Regulator. JP1 is the enable/disable jumper for the Boost Regulator portion of the MIC4832. Connecting JP1 to ground disables the boost regulator and connecting JP1 to VIN enables the boost regulator. A voltage signal may be applied to the center pin of JP1 to enable or disable the boost regulator. A low voltage signal (0V) will disable the boost regulator and 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 MIC4832 H-Bridge. JP2 is the enable/disable jumper for the HBridge portion of the MIC4832. Connecting JP2 to ground disables the H-Bridge and connecting JP2 to VIN enables the H-Bridge. Disabling the H-Bridge does not disable the boost regulator. 5. Enable/Disable the EL panel. Both the Boost Regulator and the H-Bridge of the MIC4832 must be enabled in order for the EL panel to light up. For minimum shutdown current, both the Boost Regulator and the HBridge should be turned off. The EN jumper (JP3) connects the VIN to the inductor. This jumper may be used to enable or disable the EL panel on the evaluation board, without having to use JP1 and JP2 for evaluation purposes. Ordering Information Part Number MIC4832YMM EV MIC4832YML EV Description 220Vpp MSOP Evaluation Board 220Vpp MLF Evaluation Board 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 M9999-122007 December 2007 (408) 955-1690 Micrel, Inc MIC4832 Evaluation Board Changing the Boost Regulator Frequency (fSW) The boost regulator switching frequency may be changed depending on the value of the RSW resistor. The RSW resistor on the evaluation board is equal to 332kΩ. The switching frequency may be calculated using the Rsw resistor by the following equation. Boost Regulator Output Voltage The boost regulator output voltage is set to 110V. The output peak-to-peak voltage across the EL panel is about 2 times the boost regulator output voltage (220Vp-p). EL Panel Size and Equivalent Circuit Using laboratory data, it can be shown that the EL panel has an equivalent circuit equal to a series resistance (Rs) with a series capacitance (C) and a parallel resistance (Rp). For example, if an EL panel is 4in2, then the equivalent circuit is about 20nF of capacitance in series with 450Ω of resistance and 766kΩ of parallel resistance. Figure 1 and Table 1 shows close approximations of the equivalent circuit for different EL panel sizes. fSW (kHz) = 36 R SW (MΩ ) Lowering the switching frequency will deliver more power will be delivered to the EL panel by the boost regulator; however, the switching frequency of the boost regulator should not be low enough to create over-shoot at the SW pin or at the CS pin. Refer to Table 2 for recommended values. Changing the EL Lamp Frequency, fEL The EL lamp frequency (H-Bridge frequency) may be changed depending on the value of the REL resistor. The REL resistor on the evaluation board is equal to 1.78MΩ. The EL lamp frequency may be calculated using the REL resistor by the following equation. fEL (Hz ) = 360 R EL (MΩ ) The higher the EL lamp frequency, the brighter the EL panel; however, more brightness will require more input current, thus demand more input power. More power may be delivered to the EL lamp by increasing the input voltage or by lowering the switching frequency of the boost regulator. A table of recommended components for different EL panel sizes and EL lamp frequency is shown in Figure 2 and Table 2. Figure 1. EL Panel Equivalent Circuit Table 1. EL Panel Equivalent Circuit Components Size (in2) C (nF) Rs (Ω) Rp (MΩ) 0.40 2 4600 7.66 December 2007 1.0 5 1800 3.05 2.0 10 900 1.53 3.0 15 600 1.02 4.0 20 450 0.766 6.0 30 300 0.511 2 M9999-122007 (408) 944-0800 Micrel, Inc MIC4832 Evaluation Board Typical Application Circuit Figure 2. Typical Li-Ion Powered MIC4832 Circuit Table 2. Recommended RSW & REL values for various panel sizes Size 2 (inch ) Capacitance (nF) 0.4 2 1 5 2 10 3 15 Lamp Frequency (Hz) 100 200 300 400 500 600 700 800 900 Rel (MΩ) Rsw (kΩ) fsw (kHz) Rsw (kΩ) fsw (kHz) Rsw (kΩ) fsw (kHz) Rsw (kΩ) fsw (kHz) 2.82 240 150 257 140 300 120 313 115 1.69 252 143 295 122 333 108 1.1 273 132 353 102 0.837 281 128 0.665 257 116 0.562 269 105 0.471 281 98 0.409 0.369 Note: Table 2 applies to circuit shown in Figure 2. December 2007 3 M9999-122007 (408) 944-0800 Micrel, Inc MIC4832 Evaluation Board Figure 3. Evaluation Board Schematic Bill of Materials Item Part Number Manufacturer C1 C1608X7R1A103K TDK 0.01µF Ceramic Capacitor, 10V, X7R, Size 0603 Description Qty 1 C2 C1608X5R0J225K TDK 2.2µF Ceramic Capacitor, 6.3V, X5R, Size 0603 1 C3 C2012C0G2E2272J TDK 0.0027µF Ceramic Capacitor, 250V, C0G, Size 0805 1 L1 LPF2810BT-221M(B) ABCO 220µH, 110mA ISAT. 1 D1 BAS20-V-GS18 Vishay 200V/200mA Hi-Voltage Switching Diode 1 R1 CRCW06033323FKEYE3 Vishay 332kΩ, 1%, 1/16W, Size 0603 1 R2 CRCW06031784FKEYE3 Vishay 1.78MΩ, 1%, 1/16W, Size 0603 1 R3, R4 CRCW06030R00FKEYE3 Vishay 0Ω, 1%, 1/16W, Size 0603 2 U1 MIC4832 Micrel Low Noise 220Vp-p EL Driver 1 Notes: 1. TDK: www.tdk.com 2. ABCO: www.abco.com 3. Vishay: www.vishay.com 4. Micrel, Inc.: www.micrel.com December 2007 4 M9999-122007 (408) 944-0800 Micrel, Inc MIC4832 Evaluation Board Printed Circuit Board Layout (MSOP) MSOP Top MSOP Bottom December 2007 5 M9999-122007 (408) 944-0800 Micrel, Inc MIC4832 Evaluation Board Printed Circuit Board Layout (MLF®) MLF® Top MLF® Bottom December 2007 6 M9999-122007 (408) 944-0800 Micrel, Inc MIC4832 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. December 2007 7 M9999-122007 (408) 944-0800