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IMP528
POWER MANAGEMENT
High-Voltage EL Lamp Driver
- 220 VPP Drive
The IMP528 is an Electroluminescent (EL) lamp driver with the four EL lamp driving functions on-chip. These are the switch-mode power supply, its high-frequency oscillator, the high-voltage H-bridge lamp driver and its low-frequency oscillator. The IMP528 drives EL lamps of up to 50nF capacitance to high brightness; EL lamps with capacitances greater than 50nF can be driven, but will be lower in light output. The typical regulated output voltage that is applied to the EL lamp is 220V peak-topeak. The circuit requires few external components; a single inductor, single diode, two capacitors and two resistors. Two of these resistors set the frequency for two internal oscillators. Unlike other EL lamp drivers, the IMP528 does not require an external protection resistor in series with the EL lamp. The IMP528 operates over a 2.0V to 6.5V supply voltage range. A regulated, low-power source can supply the low quiescent current of the IMP528. The inductor may be driven from an independent, unregulated supply voltage in dual supply applications. An internal circuit shuts down the switching regulator when the lamp drive voltage reaches 220V peak-to-peak. This conserves power and extends battery life. The IMP528 is available in MicroSO and SO-8 packages and in die or wafer form.
Key Features
N N N N N N N N N 220V peak-to-peak typical AC output voltage Low Power: 420A typical VDD current Wide operating voltage range - from 2.0V to 6.5V Large output load capability - drives lamps with more than 50nF capacitance Eliminates external protection resistor in series with EL lamp Adjustable output lamp frequency for control of lamp color, lamp life, and power consumption Adjustable converter frequency to minimize power consumption High-Voltage CMOS Process MicroSO package option
Applications
N N N N N N N GPS units/Pagers/Cellular phones PDAs/Handheld computers Safety illumination Portable instrumentation Battery-operated displays LCD modules Toys
4 LX CS
Block Diagram
VDD 1
RSW-OSC GND
2
Switch Oscillator
3
5
+
C Regulation Control
Q 7 VREF Bridge Output Driver Q 6 VB Q V A
-
IMP528
REL-OSC
8
Lamp Drive Oscillator
Q
528_01.eps
(c) 2001 IMP, Inc.
408-432-9100/www.impweb.com
1
IMP528
Pin Configuration
SO/ MicroSO
VDD RSW-OSC CS LX 1 2 3 4 IMP528 8 7 6 5 REL-OSC VA VB GND
528_02.eps
Pin Compatible With IMP803 and IMP560
Ordering Information
Part Number
IMP528ESA IMP528EMA IMP528/D* IMP528/D1**
Input Voltage
2.0V to 6.5V 2.0V to 6.5V 2.0V to 6.5V 2.0V to 6.5V
Regulated Output Voltage
Yes Yes Yes Yes
Temperature Range
- 40C to +85C - 40C to +85C 25C 25C
Pins-Package
8-SO 8-MicroSO Dice Dice
* Disable pad not active ** Disable pad active Add /T to ordering part number for Tape and Reel.
Absolute Maximum Ratings
VDD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.5V to +7.0V VRSW-OSC and VREL-OSC . . . . . . . . . . . . . . . . . . . -0.5V to VDD +0.3V VCS, LX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.5V to +120V Operating Temperature Range . . . . . . . . . . . . -40C to +85C Storage Temperature Range . . . . . . . . . . . . . . -65C to +150C Power Dissipation (SO) . . . . . . . . . . . . . . . . . . 400mW Power Dissipation (MicroSO) . . . . . . . . . . . . . 300mW VA, VB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.5V to VCS (pin 3) Note: All voltages are referenced to GND. These are stress ratings only and functional operation is not implied. Exposure to absolute maximum ratings for prolonged time periods may affect device reliability.
Electrical Characteristics
Unless otherwise noted, VDD = 3.0V, RSW = 910k, REL = 2.7M, and TA = 25C.
Parameter
ON-resistance of MOS Switch Output Voltage Regulation Output Voltage Peak-to-peak (in regulation) Input Current at VDD Pin Input Current at VDD Pin Quiescent VDD Supply Current, Disabled Input Current: IDD Plus Inductor Current VA-B Output Drive Frequency Switching Frequency Switching Duty Cycle
Symbol
RDS(ON) VCS VA-VB IDD IDD IDDQ IIN fEL fSW DSW
Conditions
I = 100mA VDD = 2.0 to 6.5V VDD = 2.0 to 6.5V VDD = 3.0V, See Figure 1 VDD = 5.0V VRSW-OSC < 100mV VDD = 3.0V, See Figure 1 VDD = 3.0V, See Figure 1 VDD = 3.0V, See Figure 1 VDD = 3.0V, See Figure 1
Min
Typ
3.0 110 220 420 500 20 21 250 61 88
Max
8
Units
V V A A nA mA Hz kHz %
700 750 200 31
2
408-432-9100/www.impweb.com
(c) 2001 IMP, Inc.
IMP528
Pin Descriptions
Pin Number
1 2 3 4 5 6
Name
VDD RSW-OSC CS LX GND VB
Function
Positive voltage supply for the IMP528. Inductor L may be connected here or to a separate unregulated supply. Switch-mode resistor pin. Switching frequency is determined by an external resistor, RSW. Boost converter storage capacitor. The voltage across the EL lamp is equal to twice the voltage at CS. Connection to flyback inductance, L. Ground pin. EL lamp drive. The lamp is connected in a high-voltage bridge circuit with VB providing the complementary connection to VA. The peak-to-peak AC voltage across the EL lamp is thus two times VCS. EL lamp drive. (See above) The EL lamp oscillator frequency setting pin. The oscillator frequency is controlled by external resistor REL.
7 8
VA REL-OSC
External Components
External Component
Diode Capacitor CS Resistor R EL
Description and Selection Guide
Catch diode. A fast reverse recovery diode, with BV > 150V, such as an FDLL400 (150V). This is the high voltage capacitor that stores the inductive energy transferred through the catch diode. A capacitor with WV > 120V between 10nF and 100nF is recommended. The EL lamp oscillator frequency setting resistor. This resistor, connected between the REL-OSC pin and VDD, provides an oscillator frequency inversely proportional to REL; as REL increases, the EL lamp frequency decreases along with the current drawn by the lamp. Lamp color is also determined by this frequency. A 2.7M resistor between the REL-OSC pin and the VDD supply results in a lamp frequency around 250Hz. Switching Oscillator frequency setting resistor. The switching oscillator resistor is connected between the RSW-OSC pin and the VDD supply. The switching frequency is inversely proportional to the resistor value, dropping as the resistance increases. The inductor provides the voltage boost needed by means of inductive "flyback". The internal MOSFET switch alternately opens and closes the ground connection for the inductor at the LX pin. When this internal switch opens, the inductor potential will forward-bias the catch diode and the current will pass through the storage capacitor CS, charging it to a high voltage. Smaller inductors are preferred to prevent saturation. As the value of the inductor increases (and the series DC resistance of the inductor decreases), the switching frequency set by RSW should be increased to prevent saturation. In general, smaller value inductors that can handle more current are more desirable when larger area EL lamps must be driven.
Resistor RSW
Inductor L
(c) 2001 IMP, Inc.
Electroluminescent Lamp Driver
3
IMP528
Application Information
Test and Application Circuit, 3.0V
Figure 1 shows the IMP528 configured to drive an EL lamp with a 3.0V input.
2.7M REL
1 VDD
220H1 L EN3 910k RSW FDLL400
REL-OSC VA VB GND
8 7 6 5
EL lamp 10nF (3 in2 lamp)
2 RSW-OSC 3 CS
+
VIN = 3.0V
4 LX
10nF 200V
-
0.1F2
IMP528
CS
Note: 1. Murata part # LQH4N221K04 (DC resistance <5) 2. Larger values may be required depending upon supply impedance. 3. EN is connected to VDD to enable and to GND to disable.
528_03.eps
Figure 1. 3.0V Application
Dual Supply Operation with 1.5V Battery
The IMP528 can also be operate from a single battery cell when a regulated voltage higher than 2.0V is also available. This dual supply configuration, shown in Figure 2, uses the regulated voltage to operate the IMP528 while the energy for the highvoltage boost circuit comes from the battery.
Regulated Voltage (2.0V to 6.5V) REL
1 VDD
L EN2 RSW
REL-OSC VA VB GND
8 7
EL lamp
2 RSW-OSC 3 CS
6 5
Battery Voltage
+ -
VIN 0.1F1
FDLL400
4 LX
CS 10nF 200V
IMP528
1. Larger values may be required depending upon supply impedance. 2. EN is connected to VDD to enable and to GND to disable.
528_04.eps
Figure 2. Dual Supply Operation
4
408-432-9100/www.impweb.com (c) 2001 IMP, Inc.
IMP528
High-Voltages Present
Switch Resistance
The IMP528 inductor switch resistance is typically below 3.5, as shown in Figure 3.
30 25
The IMP528 generates high voltages and caution should be exercised.
On Resistance ()
20 15 10 5 0
1
2
3
4
5
6
7
528_05.eps
VDD (V)
Figure 3. Boost Switch ON-Resistance
(c) 2001 IMP, Inc.
Electroluminescent Lamp Driver
5
IMP528
Package Dimensions
SO (8-Pin)
0- 8
Inches Min
L
Millimeters Max SO (8-Pin)*
0.069 0.010 0.020 0.010
Min
1.35 0.10 0.33 0.19 1.27 3.80 5.80 0.40 4.80
Max
1.75 0.25 0.51 0.25 4.00 6.20 1.27 2.00
E
H
C D
A
A A1 B C e E H L D
0.053 0.004 0.013 0.007 0.050 0.150 0.228 0.016 0.189
0.157 0.244 0.050 0.197
e B A1
SO (8-Pin).eps
MicroSO (8-Pin)**
A ----- 0.0433 A1 0.0020 0.0059 A2 0.0295 0.0374 b 0.0098 0.0157 C 0.0051 0.0091 D 0.1142 0.1220 e 0.0256 BSC E 0.193 BSC E1 0.1142 0.1220 L 0.0157 0.0276 a 0 6 * JEDEC Drawing MS-012AA ** JEDEC Drawing MO-187AA ---- 1.10 0.050 0.15 0.75 0.95 0.25 0.40 0.13 0.23 2.90 3.10 0.65 BSC 4.90 BSC 2.90 3.10 0.40 0.70 0 6
528_t01.at3
MicroSO (8-Pin)
a
E1 E
+
L D A2 A e b A1
0.10mm 0.004in
C
D
MicroSO (8-Pin).eps
IMP, Inc. Corporate Headquarters 2830 N. First Street San Jose, CA 95134-2071 Tel: 408-432-9100 Fax: 408-434-0335 e-mail: info@impinc.com http://www.impweb.com
The IMP logo is a registered trademark of IMP, Inc. All other company and product names are trademarks of their respective owners.
(c) 2000 IMP, Inc. Printed in USA Publication #: 2004 Revision: C Issue Date: 04/13/01 Type: Product

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