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HV845
Initial Release
Low Noise Dual EL Lamp Driver
Features
Low audible noise Independent input control for lamp selection 180VPP output voltage Split supply capability Patented output timing One miniature inductor to power both lamps Low shutdown current Wide input voltage range 2.0V to 5.8V Output voltage regulation No SCR output Available in 12-Lead QFN/MLP package
General Description
The Supertex HV845 is a low noise, high voltage driver designed for driving two EL lamps with a combined area of 3.5 square inches. The input supply voltage range is from 2.0V to 5.8V. The device is designed to reduce the amount of audible noise emitted by the lamp. This device uses a single inductor and minimum number of passive components to drive two EL lamps. The nominal regulated output voltage of 90V is applied to the EL lamps. The two EL lamps can be turned ON and OFF by the two logic input control pins, C1 and C2. The device is disabled when both C1 and C2 (pins 12 and 3) are at logic low. The HV845 has an internal oscillator, a switching MOSFET, and two high voltage EL lamp drivers. Each driver has its own half bridge common output COM1 and COM2, which significantly minimizes the DC offset seen by the EL lamp. An external resistor connected between the RSW-OSC pin and the voltage supply pin, VDD, sets the frequency for the switching MOSFET. The EL lamp driver frequency is set by dividing the MOSFET switching frequency by 512. An external inductor is connected between the LX and the VDD pins. Depending on the EL lamp size, a 1.0 to 10.0nF, 100V capacitor is connected between CS and Ground. The switching MOSFET charges the external inductor and discharges it into the capacitor at CS. The voltage at CS increases. Once the voltage at CS reaches a nominal value of 90V, the switching MOSFET is turned OFF to conserve power.
Applications
Dual display cellular phones Keypad and LCD backlighting Portable instrumentation Dual segment lamps Hand held wireless communication devices
Typical Application Circuit
330H D CS 3.3nF, 100V 3.3M 1.0F
5 1 6 CS 10 8 9 7
+
VIN
-
CIN 4.7F
LX
+
VDD
CDD 0.1F 1.5V 0 1.5V 0
845k
VDD
LX
EL1 COM1 EL2
EL Lamp 1 3.3M 1.0F EL Lamp 2
2 12 3
RSW-OSC C1 C2
-
GND COM2 4
HV845K7-G
1
HV845
Ordering Information
Device HV845
-G indicates package is RoHS compliant (`Green')
Pin Configuration
Package Options QFN/MLP - 12 HV845K7-G
VDD 1 RSW-OSC 2 C2 3
4 5 6
C1 NC EL1
12 11 10 9
EL2
8 COM1 7 COM2
GND LX CS
HV845K7-G
Absolute Maximum Ratings
Parameter Supply Voltage, VDD Output Voltage, VCS Operating Temperature Range Storage temperature Value -0.5V to 7.5V -0.5V to 120V -40C to 85C -65C to 150C
Top View
Note: Pads are on the bottom of the package. Back-side heat slug is at ground potential.
Thermal Resistance
Package QFN/MLP - 12 ja 60oC/W
Absolute Maximum Ratings are those values beyond which damage to the device may occur. Functional operation under these conditions is not implied. Continuous operation of the device at the absolute rating level may affect device reliability. All voltages are referenced to device ground.
Note: Mounted on FR4 board, 25mm x 25mm x 1.57mm
Recommended Operating Conditions
Symbol VDD TA Parameter Supply voltage Operating temperature Min 2.0 -40 Typ Max 5.8 +85 Units V
o
Conditions -----
C
Electrical Characteristics
(Over recommended operating conditions unless otherwise specified - VIN = VDD = 3.3V, TA=25C)
Symbol RDS(ON) VDD VCS VDIFF
Parameter On-resistance of switching transistor Input voltage range Output regulation voltage Differential output peak to peak voltage (EL1 to COM1, EL2 to COM2) Quiescent VDD supply current Input current into the VDD pin Average input current including inductor current when driving both lamps Output voltage on VCS when driving both lamps
Min 2.0 80 160 -
Typ 90 180 20 87
Max 10 5.8 100 200 150 250 250 30 -
Units V V V nA nA A mA V
Conditions I = 100mA --VDD = 2.0V to 5.8V VDD = 2.0V to 5.8V C1 = C2 = 0.1V C1 = C2 = 0.3V VDD = 5.8V VIN = 5.5V (See Figure 1) VIN = 5.5V (See Figure 1)
IDDQ IDD IIN VCS
2
HV845
Electrical Characteristics (cont.)
Symbol VDIF fEL fSW fSW temp D IIL IIH VIL VIH Parameter Differential output peak to peak voltage across each lamp (EL1 to COM1, EL2 to COM2) VDIFF output drive frequency Switching transistor frequency Switching transistor frequency tempco Switching transistor duty cycle Input logic low current Input logic low current Logic input low voltage Logic input high voltage Min 160 170 87 0 1.5 Typ 180 200 102 15 85 Max 200 230 118 1.0 1.0 0.3 VDD Units V Hz kHz % % A A V V Conditions VIN = 5.5V (See Figure 1) RSW = 845k RSW = 845k TA = -40C to +85C TA = -40C to +85C VDD = 2.0V to 5.8V VDD = 2.0V to 5.8V -----
Functional Block Diagram
LX CS
VDD RSW-OSC C1 C2 Control logic and switch oscillator
VCS
EL1
Disable VDD
Logic control and divide by 512 GND
Function Table
Logic Inputs C1 0 0 1 1 C2 0 1 0 1 EL1 Hi Z Hi Z ON ON EL2 Hi Z ON Hi Z ON Outputs COM1 Hi Z Hi Z ON ON COM2 Hi Z ON Hi Z ON Device OFF ON ON ON
VREF
3
C
VSENSE Output Drivers
VCS
EL2
+
COM1
VCS
COM2
HV845
Figure 1 - Test Circuit
330H** 1N4148* + VIN LX 2.1in2 EL Lamp 1*** 5 1 + VDD VIH = ON 0 = OFF VIH = ON 0 = OFF 3 CDD 0.1F 845k 2 12 VDD LX 6 CS CS 3.3nF, 100V
CIN 4.7F
EL1
10
620
13nF
RSW-OSC C1 C2
COM1 8 EL2 9 7
1.8in2 EL Lamp 2***
GND COM2 4
620
11nF
HV845K7-G
* or any (equivalent or better) > 90V, fast recovery diode ** Cooper LPO6610-334MLB *** The bigger sized lamp should be tied to EL1 and the smaller sized lamp to EL2 (pins 10 and 9 respectively)
Typical Performance
Lamp EL1 ON EL2 ON Both EL1 and EL2 ON EL1 ON EL2 ON Both EL1 and EL2 ON EL1 ON EL2 ON Both EL1 and EL2 ON 5.8V 3.0V 5.5V 5.2V VDD (V) VIN (V) IIN (mA) 7.96 6.91 13.93 7.47 6.42 13.42 7.04 6.01 12.94 88 195 VCS (VPEAK) fEL (Hz) Lamp Brightness (cd/in2) EL1 13.89 13.02 13.93 13.30 14.03 13.55 EL2 12.89 11.24 13.22 12.05 13.30 12.51
4
HV845
Split Supply Configuration
The HV845 can be used in applications operating from a battery where a regulated voltage is available. This is shown in Figure 2. The regulated voltage can be used to drive the internal logic of HV845. The amount of current used to drive the internal logic is less than 200A. Therefore, the regulated voltage could easily provide the current without being loaded down.
Figure 2 - Split Supply Configuration
Battery Voltage = VIN CIN LX D CS
EL Lamp 1
5 1 6
Regulated Voltage = VDD
CDD
RSW-OSC
VDD
LX
CS
EL1 COM1 EL2
10 8 9 7
2 12
RSW-OSC C1 C2
EL Lamp 2
VIH = ON 0 = OFF VIH = ON 0 = OFF
3
GND COM2 4
HV845K7-G
Pin Configuration and Description
Pin # 1 Function VDD Description Input voltage supply pin. External resistor connection to set both the switching MOSFET frequency and EL Lamp frequency. The external resistor should be connected between VDD and this pin. The EL lamp frequency is the switching frequency divided by 512. The switching frequency is inversely proportional to the resistor value. A 845k resistor will provide a nominal switching frequency of 102kHz and an EL lamp frequency of 200Hz. To change the frequency to fEL1, the value of the resistor RSW-OSC1 can be determined as RSW-OSC1 = (845 x 200) / fEL1 k. Enable input signal for EL Lamp 2. Logic high will turn ON the EL lamp 2 and logic low will turn it OFF. Refer to the function table. Device ground. Drain of internal switching MOSFET. Connection for an external inductor. When the switching MOSFET is turned ON, the inductor is being charged. When the MOSFET is turned OFF, the energy stored in the inductor is transferred to the high voltage capacitor connected at the CS pin. Connect a 100V capacitor between this pin and GND. This capacitor stores the energy transferred from the inductor. Common lamp connection for EL2. Common lamp connection for EL1. EL lamp 2 connection. For optimum performance, the smaller of the two lamps should be connected to this pin. EL lamp 1 connection. For optimum performance, the larger of the two lamps should be connected to this pin. No connect. Enable input signal for EL Lamp 1. Logic high will turn ON the EL lamp 1 and logic low will turn it OFF. Refer to the function table.
2
RSW-OSC
3 4 5
C2 GND LX CS COM2 COM1 EL2 EL1 NC C1
6 7 8 9 10 11 12
5
HV845
12-Lead QFN/MLP (3x3) Package (K7)
3.00 0.15 1.25 - 1.65
3.00 0.15 Note 2
1.25 - 1.65
0.25 + 0.05 - 0.07 Pin #1 Index 0.50 BSC
0.40 0.10
Top View
0 - 14O
0.75 0.05 0.20
Side View
0.0 - 0.05
Note: 1. All dimensions are in millimeters; all angles in degrees 2. Corner shape may differ from drawing
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to http://www.supertex.com/packaging.html.)
Doc.# DSFP - HV845 062306
6

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