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HV856 High Voltage Tri-EL Lamp Driver IC
Features
High voltage, Tri-EL lamp driver with common terminal Independent brightness control for all three lamps 210VPP output voltage for higher brightness 1.8V to 6.5V operating supply voltage Output voltage regulation Two-pin serial data communication for control Linear brightness control with seven steps at constant efficiency 128kHz fixed switching frequency Split supply capability Patented high efficiency EL lamp driver Single miniature inductor drives all three lamps Only four external components Burst mode power converter for best efficiency CMOS compatible serial interface with noise rejection 150nA max. leakage current when disabled Power-on reset causes all outputs to be off when first powered up Available in 10-Lead DFN package (0.8mm thickness)
General Description
The Supertex HV856 is a high voltage, triple EL lamp driver designed for driving combined EL lamps of up to 3.0in2 (1.0 in2 each). It is a higher voltage version of the HV858. The input supply voltage range is from 1.8V to 6.5V. The device is designed so that the input voltage to the inductor can differ from the input voltage to the device (split supply). The device uses a single inductor and a minimum number of passive components. The nominal regulated output voltage that is applied to the EL lamp is 105V. The HV856 has two internal oscillators; one for the internal switching MOSFET and the other for the high voltage EL lamp driver. The EL lamp frequency is fixed internally at 500Hz. The power converter oscillator runs 256 times faster than the EL lamp driver at 128kHz. An external inductor is connected between the LX and VDD pins (or between the LX pin and separate voltage source in the case of a split supply application). A 0.002-0.01F, 200V capacitor is connected between the CS pin and ground. The switching MOSFET charges the external inductor and discharges it into the capacitor at the CS pin. The voltage at CS will start to increase. Once the voltage at CS reaches a nominal value of 105V, the switching MOSFET is turned OFF to conserve power. One side of the three EL lamps is connected to the COM pin of the HV856 and the other side to the EL1, EL2, and EL3 pins of the HV856. Each EL lamp output may be independently controlled to have one of the seven brightness levels or can be completely turned OFF by a 10-bit serial data input register. The 10-bit control code has three bits to control the brightness level of each EL lamp and one bit to optionally control the power converter. The 3-bit binary brightness control code controls the number of 500Hz cycles (from 0 to 7) in a group of seven cycles.
Applications
Multi-segment, variable displays Cell phone keypads and displays MP3 players
Typical Application Circuit
+
VIN CIN LX
1 2 3
D LX
GND VDD SDI SCK CS COM EL3 EL2 EL1
10 9 8 7 6
CS
-
EL Lamp 3 EL Lamp 2 EL Lamp 1
+
VDD CDD
4 5
Serial Data in Clock
HV856K7
1
HV856
Ordering Information
Device HV856 Package Option 10-Lead DFN HV856K7-G
-G indicates the package is RoHS compliant - "Green"
Absolute Maximum Ratings
Parameter VDD SDI, SDK ISW VCS Power dissipation Storage temperature Operating temperature Value -0.5 to +7V -0.5 to +7V 0.7A peak 0.5 to +120V 1.6W -65OC to +150OC -40OC to +85OC
HV856 Pin Configuration
HV856K7
LX GND VDD SDI SCK
1 2 3 4 5 10 9
CS COM
8 EL3 7 6
EL2 EL1
10-Lead DFN
(top view) Note: The pads are at the bottom of the package. The center heat slug is at ground potential.
Recommended Operating Conditions
Symbol Parameter VDD ISW(pk) TA Supply voltage Peak switch current Operating temperature Min 1.8 -40 Typ Max 6.5 0.4 85 Unit V A
O
Conditions -------
C
Electrical Specifications (unless otherwise specified, T
Symbol Parameter RSW VCS VLAMP IDD ICS IDDQ fSW fEL VLOW VHIGH ILOGIC IIN VCS fEL ON resistance of switching transistor Output voltage Differential lamp voltage VDD supply current VCS supply current VDD leakage current when disabled Inductor switching frequency Lamp frequency Logic pin input Low level Logic pin input High level Logic pin input current Inductor current Output voltage Lamp frequency Min 95 190 0.01 10 108.8 425 -0.5 0.8VDD -0.1 Typ 4 105 210 0.15 50 100 128 500 0 VDD 0 60 94.3 500
A
= 25OC, VDD = 2.6V to 5.5V)
Max 6 115 230 0.25 100 150 147.2 575 0.2VDD VDD + 0.5 0.1 70 -
Unit V V mA A nA kHz Hz V V A mA V Hz
Conditions VDD = 1.8 to 6.5V, ISW = 100mA S1...S9 = 0, VDD = 1.8 to 6.5V, no load VCOM to any EL, no load, code* = 111 VCS = 20V, no load, PWR_ON = 1 VCS = 75V, no load S1...S9 = 0, SCK and SDI can be tied to VDD or GND See Fig.1 For all codes except code* = 000 0 < VDD < 7V See Fig.1 VDD = VIN = 3V, total lamp size = 3.0in2 (1.0in2 each) 10-bit SDI serial code = 1111111111
2
HV856
Specifications (cont.)
Symbol Parameter DMAX fCLK TSU TH Maximum PWM switch duty cycle SCK speed SDI setup time before SCK rises SDI hold time before SCK rises Min 80 30 30 Typ 88 Max 94 1 Units Conditions % MHz ns ns VCS = 20V, RLOAD = 20 -------
* Code refers to the 3-bit Brightness Control Code for the respective EL Lamp
Logic Input Conditions
The serial data input consists of a 10-bit string, three bits of brightness control and one bit (10th bit) to optionally control the power converter. The power converter runs if any of the EL lamps has a non-zero brightness value or if the PWR_ON bit is high while the other nine bits are low. 1. SDI may be H or L if SCK is H.
EL Lamp Brightness Control
The EL lamp brightness control is a 3-bit binary number stored in a latch, which is provided by a serial to parallel conversion shift register. 1. If all the three bits for a designated EL lamp are L, the differential voltage across that lamp will be zero. 2. If any of the three bits for a designated EL lamp is H:
2. SCK may be H or L if SDI is H. 3. While inputting serial data to the shift register, SDI can change value only when SCK is L. 4. The previous ten bits of serial input will be latched when SDI makes L to H transition while SCK is H. a. The 3-bit value sets the average number of cycles for which the EL lamp voltage is non-zero. b. The EL lamp brightness is linearly proportional to the binary lamp control code.
Logic Input Diagram
S1 S2 S3 S4 S5 S6 S7 S8 S9 S10
SDI
MSB of EL1 LSB of EL1 MSB of EL2 LSB of EL2 MSB of EL3 LSB of EL3 PWR_ON
EL1 Control
SCK
EL2 Control
EL3 Control
Note: 1. Serial data is latched when SDI makes L to H transition and while SCK is H. 2. S1 is the first serial data input being fed.
Latches in Data
3
HV856
Logic Truth Table
L = Low (L = 0 to L < 20% of VDD) H = High (80% of VDD < H = VDD) - = Does not control brightness of the designated EL lamp
Brightness Level Device Disabled All Lamps Off Device Enabled 7/7 6/7 5/7 EL1 4/7 3/7 2/7 1/7 OFF 7/7 6/7 5/7 EL2 4/7 3/7 2/7 1/7 OFF 7/7 6/7 5/7 EL3 4/7 3/7 2/7 1/7 OFF
S1 L L H H H H L L L L -
S2 L L H H L L H H L L -
S3 L L H L H L H L H L -
S4 L L H H H H L L L L -
S5 L L H H L L H H L L -
S6 L L H L H L H L H L -
S7 L L H H H H L L L L
S8 L L H H L L H H L L
S9 L L H L H L H L H L
S10 L H -
4
HV856
Functional Block Diagram
D
+
VIN
CIN VDD Enable
LX LX CS
CS
Switch Osc EL1
VSENSE VREF EL1 EL2 EL3 COM Output Drivers
VCS
Disable
Logic Control SDI SCK
Note: This drawing is a generalized representation. Actual internal circuitry may differ.
Differential Output Waveform
The following is the differential output waveform across the lamp for each 3-bit input code for each lamp.
Code 000 500Hz Code 001
Code 010
Code 011
Code 100
Code 101
Code 110
Code 111
Group of 7 Cycles .....Pattern Repeats....
5
VCS VCS
GND
+
EL2
EL3
COM
HV856
Test Circuit
+ VIN LX = 68H* CIN 4.7F 1 2 3 + VDD CDD 0.1F Stream of Serial Data (1's and 0's) 4 5 D = BAS21 LX GND VDD SDI SCK 10 9 8 7 6 EL Lamp 3 (1.0in2) EL Lamp 2 (1.0in2) EL Lamp 1 (1.0in2) CS 3.3nF, 200V CS COM EL3 EL2 EL1
HV856K7
*Murata Inductor - LQH32CN680 Note: Maximum lamp size for each segment is 1.0 in2. To drive larger size lamps, any combination of EL1, EL2 and EL3 can be paralleled. However, the 3-bit serial data input code (for each output) should be such that the paralleled outputs have the same code.
Typical Performance (V
1ST 9-bit SDI Code 000111111 001111111 010111111 011111111 100111111 101111111 110111111 111111111
DD
= 3.0V, VIN = 3.3V)
EL1 Brightness Level 0/7 1/7 2/7 3/7 4/7 5/7 6/7 7/7 ft-lm 0 1.93 4.05 6.15 8.20 10.13 12.30 14.80 cd/m2 0 6.60 13.85 21.03 28.04 34.64 42.07 50.62
IIN (mA) 48.72 50.21 52.42 54.03 55.45 56.63 58.41 60.40
VCS (VPEAK) 103 103 103 103 103 103 103 103
HV856 Pinout
Pin 1 2 3 4 5 6 7 8 9 10 Name LX GND VDD SDI SCK EL1 EL2 EL3 COM CS Description Inductor pin Ground pin Input voltage supply pin. (It is common practice to use a bypass capacitor as close as possible to the device on this pin) Serial data input pin Serial clock input pin EL Lamp 1 pin EL Lamp 2 pin EL Lamp 3 pin Common pin for one side of all three EL lamps High voltage capacitor pin
6
HV856
10-Lead DFN (K7) Package Outline
3.00 2.20
3.00 Note 2
1.60
0.30
+0.15 -0.10
Pin #1 Index
0.50 BSC
0.25
+0.05 -0.07
Top View
0O - 14O
0.20 0.75 - 0.80 0.0 - 0.05
Side View
Notes: 1. All dimensions are in millimeters; 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-HV856 A111306
7

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