Datasheet MC33441DTBEL, MC33441DTBR2 Datasheet (MOTOROLA)

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Page 1

 Semiconductor Components Industries, LLC, 2000

April, 2000 – Rev. 1

1 Publication Order Number:

MC33441/D

MC33441

Electroluminescent Lamp Driver IC

3.5V and is capable to supply a typical 140Vpp AC output voltage. The standby current of the device is typically 10nA which is ideal for low power portable products. Externally, one inductor and one resistor are needed to generate the desirable voltage charge and to fine tune the oscillator’s frequency. This device is offered in 8–Pin TSSOP miniature package. The operating temperature is –20°C to 70°C.

Features:

• Battery Operation 1.8V – 3.5V

• Typical Voltage Output 140Vpp

• Typical Standby Current 10nA

• Internal Oscillator with External Tuning Resistor

• Enable Control Pin with a 300K Internal Pull–Down Resistor

• 8–Pin TSSOP Package (Thickness = 1.05mm, Width = 4.5mm,

Length = 3.1mm & Lead Pitch = 0.65mm)

Types of Applications:

• Pagers, Cellular Phones, Portable CD Players/Minidisks

• Databanks, Calculators

Simplified Block Diagram

FREQUENCY

DIVIDER

VDD

ENB

RT1

OSC

VSS

H–BRIDGE

COIL

DRIVER

COIL

EL1

EL2

FILTER

COIL

Device Package Shipping

ORDERING INFORMATION

MC33441DTBR2 TSSOP–8 2500 Units / Reel

TSSOP–8

DTB SUFFIX

CASE 948J

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PIN CONNECTIONS AND

MARKING DIAGRAM

VSS COIL

FILTER

(Top View)

ENB

RT1

VDD

EL2

EL1

M33

441

ALY

A = Assembly Location L = Wafer Lot Y = Y ear W = Work Week

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Figure 1. Test Circuit

H–BRIDGE

VSS

ENB

RT1

OSC

FREQ.

DIVIDER

VDD

COIL DRIVER

EL LAMP

AND2

EL1

EL2

FILTER

COIL

AND2

INDUCTOR

FILTER

EXT

Battery / V

OPTIONAL

MAIN SWITCH

PIN FUNCTION DESCRIPTION

Pin No.

(TSSOP–8)

Name Description

Pin 1

VDD

ББББББББББББББББББББББ

Input voltage supply

Pin 2

ENB

ББББББББББББББББББББББ

Enable the whole device to operate

Pin 3

RT1

ББББББББББББББББББББББ

Internal oscillator’s fine tuning resistance input

Pin 4

VSS

ББББББББББББББББББББББ

Analog/Power ground

Pin 5

COIL

ББББББББББББББББББББББ

Coil/Inductance input

Pin 6

Filter

ББББББББББББББББББББББ

EL Filter

Pin 7

EL2

ББББББББББББББББББББББ

EL lamp driver output 2

Pin 8

EL1

ББББББББББББББББББББББ

EL lamp driver output 1

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MAXIMUM RATINGS (T

= 25°C, unless otherwise noted.)

Rating

Symbol Max Unit

Power Supply Voltage

7.5

ББББББББББББ

Digital Input Voltage Range

ÁÁ

LOGIC = 0 LOGIC = 1

ÁÁÁ

0.5

Operating Junction Temperature

J(max)

150

°C

Operating Ambient Temperature

–20 to +70

°C

Storage Temperature Range

stg

–50 to +150

°C

Power Dissipation

300

Thermal Resistance, Junction–to–Air

θJA

178

°C/W

DC ELECTRICAL CHARACTERISTICS (V

= 2.65V , TA = 25°C, Lamp Capacitance = 2.2nF, Coil = 1mH unless

otherwise noted.)

Characteristic

Symbol Min Typ Max Unit

Supply Voltage

1.8

–

3.5

Output Voltage (1.8V < VDD ≤ 3.5 V)

120

140

160

Peak Coil Current (1.8V < VDD ≤ 3.5 V)

COIL

–

150

Average Coil Current from Battery (1.8V < VDD ≤ 3.5 V)

VDD

–

mA dc avg

Standby Current (VDD = 3.0 V, ENB = 0)

STAND

–

100

Clock Frequency (R

EXT

= 125KW)

osc

112

140

168

kHz

Lamp Drive Frequency (F

osc

Divide by 384)

–

364.6

–

Coil Drive Frequency ( F

osc

Divide by 4)

COIL

–

kHz

Coil Drive Clock Duty Cycle

COIL

–

EL Lamp Capacitance Range

–

2.2

–

EL1

TIME

EL2

TIME

Typical Vpp = 140V

(160V max)

Figure 2. Output Waveform

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Figure 3. Output Waveform vs. Time

VDD = 2.65V Lamp Freq. = 365Hz EL Lamp = 2.2nF

X = 1ms/div, Y = 50V/div

OPERA TING DESCRIPTION

General

The MC33441 is a DC–AC inverter integrated circuit for driving EL lamps. It can boost the supply voltage to the level required by EL lamps and also provide high voltage AC lamp excitation. It consists of an oscillator, a frequency divider, a coil driving circuit and a switched H–bridge network. The input supply voltage range is from 1.8V to 3.5V and is capable to supply a typical 140Vpp AC output voltage. The standby current of the device is typically 10nA which is ideal for low power portable products. Externally, one inductor and one resistor are needed to generate the desirable voltage charge and to fine tune the oscillator’s frequency. This device is offered in 8–Pin TSSOP packages. The operating temperature is –20°C to 70°C.

Oscillator and Frequency Divider

Two circuits are put together to form the oscillator. They are Vref and Ibias. The functionality of Vref block is to generate a zero temperature coefficient (TC) voltage reference which is about 1.27V. This 1.27V will then be used in Ibias circuit to provide current biasing to all of the internal circuits with the value equal to Vref divided by an internal resistor. Besides of that, an external resistor is also connected to this circuit block for setting the oscillator’s frequency. The temperature coefficient is dominated by the value of that resistor. Therefore, if a low TC resistor is used, the oscillator frequency’s TC can be kept low.

The current mirrors with the induced current equal to the Vref divided by an external resistor are used to charge and discharge an internal capacitor to provide a 50% duty cycle clock signal. This original clock pulse will then be fed into the frequency divider which will generate two additional clock signals with different frequency and duty cycle to the coil–driver and the H–bridge circuits. The oscillator frequency is governed by the following equation:

OSC

6 R

EXT

INT

HzǓ+

1.667 10

EXT

COIL

= F

OSC

B 4

FEL = F

OSC

B 384

where C

INT

is about 10pF.

Coil Driver

The coil driver is basically a simplified boost converter. It takes a higher frequency clock signal from the frequency divider to turn on/off the main switch alternatively. When the main switch is on, current will flow through the coil to ground. Once the switch is being turned off, the energy stored in the coil will be released to the external capacitor (EL lamp) through an internal diode. According to the frequency of the clock signals between the coil driver and the H–bridge, the external capacitor (EL lamp) will be charging to the desirable level.

Current limit circuit (typical 70mA & max. 150mA) is implemented in this device. Since the current through the coil will increase corresponding to the input voltage, if the input voltage is high and the inductance of the coil is small, the coil can be saturated. The current limit feature is used to avoid this happen. The main switch is parallel to a much smaller switch which has their collector and their base connected together. However, the emitter of the smaller switch is tied to a sensing resistor while the emitter of the main switch is connected to ground. The coil current will split into two according to the sizing ratio between the main and the smaller switch. The current through the smaller switch will also flow through the sensing resistor and generates a voltage. If the voltage across this sensing resistor is above the pre–set value, then both switches

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will be turned off and the energy will release to the EL lamp. And, those switches will remain off until the next clock cycle.

H–Bridge Network

To achieve the 140V peak–to–peak voltage, H–bridge network is used to charge and discharge the EL lamp. The switching frequency of the bridge network is controlled by a clock signal from the divider with its frequency much lower than the one to the coil–driver. Moreover, to reduce the current consumption, the biasing current to the two low–side switches of the H–bridge is not activated until the coil–driver circuit needed to release the energy to the EL lamp. Then, the biasing circuit will be on and be ready before the main switch in the coil–driver really starts to turn off.

External Components

System designer will base on the application to decide the size and the type of the EL lamp to be used. The external resistance (R

EXT

) at RT1 pin determines the excitation frequency (FEL) for

the lamp. The relationship between R

EXT

and the frequency is:

FEL = F

OSC

B 384

By substitute the equation of F

OSC

from Oscillator &

Frequency Divider.

FEL+

4.341 10

EXT

4.341 10

Moreover, if a low TC resistor is used, the oscillator frequency’s TC can be kept low. The filter capacitor is to provide a smooth and more stable output waveform for the EL lamp. The value of this capacitor depends on the input voltage and the coil’s inductance value. Equations below can be used to estimate filter capacitor’s value at different input voltage.

Best Case Approximation for the Filter Capacitor:

FILTER

0.026 (Vin*

VSW)

ń(L

OSC

)

Worst Case Approximation for the Filter Capacitor:

FILTER

0.085 (Vin*

VSW)

ń(L

OSC

)

where VIN is the input voltage, VSW is voltage across the switch when it is on, L is the coil’s value and F

OSC

is the

clock frequency.

Measurement below is recorded with the condition: coil = 1mH, EL lamp = 2.2nF and at room temperature.

Table 1: Reference for C

FILTER

VDD R

EXT

FILTER

1.8V

100K–130K

5n–10nF

2.0V

100K–130K

10n–22nF

2.5V

100K–130K

10n–22nF

3.0V

100K–130K

22nF–33nF

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TYPICAL OPERATING CHARACTERISTICS

Figure 4. Oscillator Frequency vs. R

EXT

Figure 5. Lamp Frequency vs. R

EXT

Figure 6. Current Consumption vs. Coil Inductance Figure 7. Current Consumption vs. V

Figure 8. Output Voltage vs. R

EXT

Figure 9. Output Voltage vs. Coil Inductance

COIL INDUCTANCE (mH)

LAMP FREQ. (Hz)

VOUT (V)

EXT

(OHM)

100

150

250

200K

300

200

50K 75K 100K 150K

VDD = 2.65V Coil = 1mH EL lamp = 2.2nF

OSC. FREQ. (KHz)

COIL INDUCTANCE (mH)

I (mA)

EXT

(OHM)

VOUT (V)

VDD (V)

I (mA)

EXT

(OHM)

100

200

300

500

200K

600

400

50K 75K 100K 150K

VDD = 2.65V Coil = 1mH EL lamp = 2.2nF

1.47

0.56 0.82 1 1.33

VDD = 2.65V Lamp Freq. = 365Hz EL lamp = 2.2nF

3.5

1.8 2 2.65 3

Coil = 1mH Lamp Freq. = 365Hz EL Lamp = 2.2nF

120

122

124

126

130

200K

132

128

50K 75K 100K 150K

VDD = 2.65V Coil = 1mH EL Lamp = 2.2nF

134

136

138

110

115

120

125

135

1.47

130

0.56 0.82 1 1.33

VDD = 2.65V Lamp Freq. = 365Hz EL Lamp = 2.2nF

140

145

150

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APPLICATION INFORMA TION

EL Lamp Selection

EL lamps are a laminate which exhibit a capacitance on the order of 2.5nF to 3.5nF per square inch. The light will emit as the high voltage is applied across the electrodes of this capacitance. The color of the emitted light is determined by the type of chemical used and the frequency of the excitation voltage. On the other hand, the lamp brightness increases approximately the square of the applied voltage and nearly linear to the excitation frequency. Once a lamp has been selected, the operating frequency and the essential voltage for the optimum performance is determined. Then, the driver circuit can begin to design.

Inductor Selection (L1)

Use a 1mH/0.15A inductor for MC33441. Higher inductor values can be used to reduce the peak transient coil current from the battery supply. As the value of the inductor (L1), increases, the resistor (R1) value may need to increase correspondingly to provide optimum performance. While a lower inductor values lead to smaller physical size, it will generate a higher peak coil current. A lower resistor (R1) value should be used when a lower inductance coil is being used.

The inductor must have a saturation current rating equal

to or bigger than the peak coil current which is 150mA.

Filter Capacitor Selection (C2)

See Table 1 for the estimated value of the filter capacitors based on the input voltage supply. Since the maximum voltage of the filter capacitor can reach 70V or even 80V, capacitor with high voltage rating will be required.

Resistor Selection (R1)

Since the fundamental frequency of the oscillator is set by the external resistor (R1), the temperature coefficient of the frequency is dominated by the value of this resistor. A low temperature coefficient (TC) resistor is suggested to use for keeping the variation of oscillator’s frequency low against the operation temperature range. (See Page 4, Fig. 3 & Fig. 4)

R1+R

EXT

4.341 10

Layout

The MC33441 is high output voltage operation make PC board layout critical to minimize ground bounce and noise. Locate input bypass capacitor, filter capacitor and oscillator’s resistor as close to the device pins as possible.

Figure 10. MC33441 Demo Board Schematic

MC33441

VDD

(TSSOP–8)

0.1µF

L1 1mH

ENABLE

R1 130K

ENB RT1 VSS

EL1 EL2

FILTER

COIL

EL–LAMP

1 2

3 4

8 7

6 5

BATTERY

PB1

C2 27nF/100V

COMPONENT SUPPLIER

Supplier Part Number Description Phone

ББББББББ

Tech–Wave Industrial Co., Ltd.

БББББ

Part# CC–0012

ББББББББББ

EL–Lamp: 14.5mm x 47mm Color: Y ellow–Green

БББББ

(886)–2–22692827

ББББББББ

Coils Electronics Co., Ltd.

БББББ

Part# CRCH664– 102K–831015

ББББББББББ

Inductor: 1mH / 0.15A

БББББ

(852)–2341–5539

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Figure 11. MC33441 PC Board – Top View

Figure 12. MC33441 Component Placement Guide – Component Side

Figure 13. MC33441 PC Board – Bottom View

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P ACKAGE DIMENSIONS

TSSOP–8

DTB SUFFIX

CASE 948J–01

ISSUE O

DIM MIN MAX MIN MAX

INCHESMILLIMETERS

A 2.90 3.10 0.114 0.122 B 4.30 4.50 0.169 0.177 C ––– 1.20 ––– 0.047 D 0.05 0.15 0.002 0.006 F 0.50 0.75 0.020 0.030 G 0.65 BSC 0.026 BSC H 0.50 0.60 0.020 0.024

J 0.09 0.20 0.004 0.008

J1 0.09 0.16 0.004 0.006

K 0.19 0.30 0.007 0.012

K1 0.19 0.25 0.007 0.010

L 6.40 BSC 0.252 BSC M 0 8 0 8

NOTES:

1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982.

2. CONTROLLING DIMENSION: MILLIMETER.

3. DIMENSION A DOES NOT INCLUDE MOLD FLASH. PROTRUSIONS OR GATE BURRS. MOLD FLASH OR GATE BURRS SHALL NOT EXCEED

0.15 (0.006) PER SIDE.

4. DIMENSION B DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSION. INTERLEAD FLASH OR PROTRUSION SHALL NOT EXCEED 0.25 (0.010) PER SIDE.

5. DIMENSION K DOES NOT INCLUDE DAMBAR PROTRUSION. ALLOWABLE DAMBAR PROTRUSION SHALL BE 0.08 (0.003) TOTAL IN EXCESS OF THE K DIMENSION AT MAXIMUM MATERIAL CONDITION.

6. TERMINAL NUMBERS ARE SHOWN FOR REFERENCE ONLY.

7. DIMENSION A AND B ARE TO BE DETERMINED AT DATUM PLANE –W–.

____

SECTION N–N

SEATING PLANE

IDENT.

PIN 1

SEE DETAIL E

DETAIL E

2X L/2

–U–

U0.15 (0.006) T

0.10 (0.004) V

0.10 (0.004)

–T–

–V–

–W–

0.25 (0.010)

8x REFK

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Notes

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Notes

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without further notice to any products herein. SCILLC makes no warranty , representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability , including without limitation special, consequential or incidental damages. “Typical” parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including “Typicals” must be validated for each customer application by customer’s technical experts. SCILLC does not convey any license under its patent rights nor the rights of others. SCILLC products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the SCILLC product could create a situation where personal injury or death may occur. Should Buyer purchase or use SCILLC products for any such unintended or unauthorized application, Buyer shall indemnify and hold SCILLC and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly , any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that SCILLC was negligent regarding the design or manufacture of the part. SCILLC is an Equal Opportunity/Affirmative Action Employer .

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MC33441/D

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Datasheet MC33441DTBEL, MC33441DTBR2 Datasheet (MOTOROLA)

Specifications and Main Features

Frequently Asked Questions

User Manual