MP1026
CCFL Driver
For Handheld Display Applications
The Future of Analog IC Technology
DESCRIPTION
FEATURES
The MP1026 is a Power IC that offers a
complete solution for driving a Cold Cathode
Fluorescent Lamp (CCFL). This Power IC
converts unregulated DC voltage to a nearly
pure sine wave required to ignite and operate
the CCFL.
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The MP1026 greatly increases power
conversion efficiency and supports both analog
and burst mode dimming, simplifying the module
implementation. The MP1026 offers the
following distinct performance advantages:
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More light for less power
Small board implementation
Low RF emission
Low external components cost
4.5V to 14V Power Input (VBatt)
Increase Transformer Reliability
Open Lamp Timer and Regulation
Current and Voltage Feedback Control
Logic Level Burst Mode Control
Supports Open/Short Lamp Protection
Soft-Start
Outputs are Short Circuit Protected
Allows Burst-Mode Operation
Improved Line Transient Response
Tightened Lamp Current Accuracy
APPLICATIONS
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The MP1026 is suitable for 2-Cell Li-Ion battery
applications using 5V, 9V, or 12V adapters as
the power source.
Portable DVD Players
PDAs
Camcorders
Digital Cameras
“MPS” and “Monolithic Power Systems” are Registered Trademarks of
Monolithic Power Systems, Inc.
The MP1026 is covered by US Patents 6,316,881 and 6,114,814.
TYPICAL APPLICATION
Cisb
CbaR
Cft
Ccomp
Rs
DA
VDD
Risb
CbtR
11
Cp
RIL
BtL
Rdamp
10
PGnd
9
OutL
8
Batt
7
Vdd
6
En
5
Bosc
DBrt
4
3
IL
2
1
Abrt
MP1026
ABrt
Rlfb
Rsfb
BtR
12
PGnd
13
Batt
OutR
14
15
Comp
Vdd
16
17
FT
18
ISFB
VLFB
19
20
AGnd
Rbosc
Cs1
CbtL
DB
T1
DBrt
Gnd
CbaL
Cvdd
Cdbr
Rdbr
Cbosc
En
Cs2
Csfb
Rbleed
DA, DB: required for VBATT < 7V
IN4148 or BAT54
Cba
VBATT
MP1026 Rev. 1.6
9/24/2007
F1
MP1026_TAC_S01
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MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2007 MPS. All Rights Reserved.
1
MP1026 – CCFL DRIVER FOR HANDHELD DISPLAY APPLICATIONS
ABSOLUTE MAXIMUM RATINGS (1)
PACKAGE REFERENCE
TOP VIEW
Abrt
1
20
AGnd
IL
2
19
ISFB
Bosc
3
18
VLFB
DBrt
4
17
FT
En
5
16
Comp
Vdd
6
15
Vdd
Batt
7
14
Batt
OutL
8
13
OutR
PGnd
9
12
PGnd
BtL
10
11
BtR
EXPOSED PAD
CONNECT TO
AGND (PIN 20)
Recommended Operating Conditions
MP1026_PD01-TSSOP20F
Package
Temperature
MP1026EF
TSSOP20F
–20°C to +85°C
For Tape & Reel, add suffix –Z (eg. MP1026EF–Z)
For Lead Free, add suffix –LF (eg. MP1026EF–LF–Z)
(2)
Battery Voltage VBATT ....................... 4.5V to 14V
Input Voltage VDD ............................ 4.5V to 5.5V
Enable Voltage VEN ............................ 0V to 5.0V
Brightness Voltage ............................ 0V to 2.0V
Operating Frequency............................... 60KHz
Operating Temperature ............. –20°C to +85°C
Thermal Resistance
Part Number*
*
Input Voltage (VBATT).................................... 16V
Power Dissipation...................................... 1.0W
Logic Inputs .................................... 0.3V to 6.0V
IL, ISFB Inputs.................................... +6V / –2V
Junction Temperature...............................150°C
Lead Temperature (Solder) ......................260°C
Operating Frequency............................. 150KHz
Storage Temperature .............. –55°C to +150°C
(3)
θJA
θJC
TSSOP20F ............................. 40 ....... 6.... °C/W
Notes:
1) Exceeding these ratings may damage the device.
2) The device is not guaranteed to function outside of its
operating conditions.
3) Measured on approximately 1” square of 1 oz copper.
ELECTRICAL CHARACTERISTICS
Batt = 14V, VDD = 5V, TA = +25°C, unless otherwise noted.
Parameter
Voltage Supply
Vdd Off Current
Batt Off Current
Vdd Current (operating)
Shutdown Logic
Fault Timer Threshold
Fault Timer Sink Current
Fault Timer Source Current
Open Lamp
Secondary Overload
Enable Voltage Low
Enable Voltage High
MP1026 Rev. 1.6
9/24/2007
Symbol Condition
Min
Idd(off) Enable = 0V
IBatt(off) enable = 0V
Idd(on)
Vth(FT)
VL(En)
VH(En)
Typ
Max
Units
1.2
400
20
1.8
µA
µA
mA
V(VLFB) > 0, V(ISFB) < 1.2
1.2
1
V
µA
V(VLFB) > 0, V(ISFB) < 1.2
V(ISFB) > 1.2
1
115
µA
µA
V
V
0.6
1.5
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© 2007 MPS. All Rights Reserved.
2
MP1026 – CCFL DRIVER FOR HANDHELD DISPLAY APPLICATIONS
ELECTRICAL CHARACTERISTICS (continued)
Batt = 14V, VDD = 5V, TA = +25°C, unless otherwise noted.
Parameter
Output Drivers
Symbol
Switch On Resistance (4)
Condition
R(ON)OUTL,O
UTR
Ton(min) Vdd = 5V
Batt = 4.5V, Vcomp = 0V
Ton(min) Vdd = 5V
Batt = 14V, Vcomp = 0V
First Pulse Ton(min)
Batt = 4.5V
Vdd = 5V
First Pulse Ton(min)
Batt = 14V
Vdd = 5V
Brightness Control
Sense Full Brightness
V(IL)
V(Abrt) = 2.0V
Sense Full Dim
V(IL)
V(Abrt) = 0V
Lamp Current Regulation
4.5v < V(Batt) < 14V
Burst Oscillator Sink Current
I(Bos)
Burst Oscillator Peak
V(Bos)
Voltage
Fault Loop Control
Open Lamp Threshold
Vth(VLFB)
Secondary Current
Vth(ISFB)
Threshold
Fault Mode Comp Current
I(Cmp) V(VLFB) < 0V, V(ISFB) > 1.2V
Min
Typ
Max
Units
0.085
0.12
0.15
Ω
360
100
1800
350
ns
ns
8300
ns
1300
ns
385
115
3
370
410
130
mV
mV
%
µA
1.8
V
0
V
1.2
V
460
µA
Note:
4) This parameter is guaranteed by design.
PIN FUNCTIONS
Pin #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Name
ABrt
IL
Bosc
DBrt
En
Vdd
Batt
OutL
PGnd
BtL
BtR
PGnd
OutR
Batt
Vdd
Comp
FT
VLFB
ISFB
AGnd
MP1026 Rev. 1.6
9/24/2007
Description
Analog Dimming.
Lamp Current Feedback Sense Input.
Burst Oscillator Timing.
Burst Mode Dimming.
Chip Enable. Do not float this pin.
Supply Voltage.
Power Supply Input.
Output to Load (Tank Circuit).
Power Ground.
Regulated Output Voltage for Bootstrap Cap on Phase L.
Regulated Output Voltage for Bootstrap Cap on Phase R.
Power Ground.
Output to Load (Tank Circuit).
Power Supply Input.
Supply Voltage.
Loop Compensation Cap.
Fault Timer.
Open Lamp Detect (Lamp Voltage Feedback).
Shorted Lamp Detect (Secondary Current Feedback).
Small Signal Ground (Connect the Exposed Pad to Pin 20).
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© 2007 MPS. All Rights Reserved.
3
MP1026 – CCFL DRIVER FOR HANDHELD DISPLAY APPLICATIONS
BLOCK DIAGRAM
Vdd
6, 15
DBrt
4
Bosc
3
ENABLE
BURST
DIMMING
RAMP
OSCILLATOR
+
En
20 AGnd
VDRV
--
5
REF
10 BtL
BURST
DIMMING
CLOCK
7
Batt
8
OutL
+
-+
-CONTROL
LOGIC
9, 12 PGnd
-+
13 OutR
-+
14 Batt
11 BtR
SHORT
CIRCUIT
FT 17
PROTECTION
+
--
19 ISFB
1.2V
OPEN LAMP
FAULT
(OLF)
+
--
Comp 16
COMP
18 VLFB
-GM
HALF
WAVE
RECTIFIER
+
2
IL
1
Abrt
MP1026_BD01
Figure 1—Functional Block Diagram
MP1026 Rev. 1.6
9/24/2007
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2007 MPS. All Rights Reserved.
4
MP1026 – CCFL DRIVER FOR HANDHELD DISPLAY APPLICATIONS
APPLICATION INFORMATION
Brightness Control
The MP1026 can operate in three modes:
Analog Mode, Burst Mode with a DC input, or
Burst Mode with an external PWM. The three
modes are dependent on the pin connections
as per Table 1.
Choosing the required burst repetition
frequency can be achieved by an RC
combination, as defined below. The MP1026
has a soft on and soft off feature to reduce
noise, when using burst mode dimming.
1. Select a Minimum Duty Cycle (DMIN). This is
the ratio TFALL / (TFALL + TRISE) for the burst
oscillator.
For example: 10%
2. Determine Rbosc by the formula:
⎤
⎡⎡
1
⎤
− 1) ⎥
⎥
⎢ ⎢ 1.68 × (
DMIN
⎢⎢
⎥ + 4⎥
⎥
⎢⎢
0.42
⎥
⎥
⎢⎢
⎥
⎦
⎣
⎦
⎣
Rbosc =
−6
350 × 10
3. Select a burst frequency and find TTOTAL
where:
TTOTAL = 1/burst frequency.
(1 − DMIN )
0.42 × Rbosc × fbosc
In a typical application, Rbosc=470kΩ and
Cbosc=22nF.
MP1026 Rev. 1.6
9/24/2007
Pin Connection
Pin 1
Pin 4
Pin 3
ABrt
DBrt
Bosc
0 – 1.9V
VRef
AGnd
Rbosc
VRef
0 – 1.8V
Cbosc
VRef
PWM
Rsfb >
1.5V
1 .2 V
= 1.7kΩ
0.7mA
The recommended value is 3.9kΩ to 10kΩ
(typically 4.7kΩ).
Csfb <
Table 1—Function Mode
Analog Mode
Burst Mode with
DC input voltage
Burst Mode from
external source
Excessive Secondary Current (Shorted Lamp
and UL safety specs): The ISFB pin (#19) is
used to detect whether excessive secondary
current has occurred. During normal operation
the peak ISFB voltage is below 1.2V. If a fault
condition occurs that increases the secondary
current, then the voltage at ISFB will be greater
than 1.2V. When that occurs, a 120µA current
source will inject into the FT pin. If the voltage
at the FT pin exceeds 1.2V, then the chip will
shut down.
Sensing network: Rsfb, Risb, Csfb and Cisb.
Where fbosc is burst frequency rate in Hz and
Tmin is the Minimum burst time in sec.
Function
Fault Protection
Open Lamp: The VLFB pin (#18) is used to
detect whether an open lamp condition has
occurred. During normal operation the VLFB pin
is typically at 5V DC with an AC swing of ±2.5V.
If an open lamp condition exists then the AC
voltage on the VLFB line will swing below zero
volts. When that occurs, the IC regulates the
VLFB voltage to 10V p-p and a 1µA current
source will inject into the FT pin. If the voltage
at the FT pin exceeds 1.2V, then the chip will
shut down.
The following is the design reference for the
secondary winding current.
Then determine Cbosc by the formula:
Cbosc =
Brightness Polarity:
Burst: 100% duty cycle is at 1.8V
Analog: 1.9V is maximum brightness
0.7 mA
KHz = 93nF
1 . 2 V × 2π
Select a capacitor with less than 93nF
capacitance for Csfb and make the FB pin
voltage peak value around 0.9V in normal
operation.
The 0.7mA DC and 0.7mA/KHz AC current
values are taken from the UL60950 safety
requirement.
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MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2007 MPS. All Rights Reserved.
5
MP1026 – CCFL DRIVER FOR HANDHELD DISPLAY APPLICATIONS
Cisb and Risb make up a high-pass filter,
wherein the corner frequency should be
between 1KHz and 2KHz so as to minimize the
attenuation of the AC signal.
The recommended value for Risb is 100kΩ.
1
1.6nF =
> Cisb
2π × Risb × 1KHz
1
Cisb >
= 0.8nF
2π × Risb × 2KHz
A typical value for Cisb is 1.2nF.
Fault Timer: The timing for the fault timer will
depend on the sourcing current, as described
above, and the capacitor on the FT pin. The
user can program the time for the voltage to
rise before the chip detects a “real” fault. When
a fault is triggered, then the internal drive
voltage (VDrv) will collapse from VDD to 0V.
For open lamp time:
T(open _ lamp ) =
C ft (µF) × 1.2V
1µA
For secondary short turn off time:
T(short ) =
C ft (µF) × 1.2V
120µA
The off time when a resistive short occurs
across the lamp will be approx 100 times faster
than the open lamp time. To reduce the turn off
time even further, then by modifying the
connection at the FT node to:
There is no impact on the open lamp time. The
secondary short turn off time is:
T(short ) =
C ft 2 (µF) × 1.2V
120µA
With a smaller capacitor value for Cft2 (when
compared to Cft), the turn off time for the
secondary short will be further reduced.
Lamp Startup
The strike voltage of the lamp will always be
guaranteed at any temperature because the
MP1026 uses a resonant topology for switching
the outputs. The device will continue to switch
at the resonant frequency of the tank until the
strike voltage is achieved. This eliminates the
need for external ramp timing circuits to ensure
startup.
ESD Resistor
It
is
recommended
that
a
resistor
(RIL=470Ω~1kΩ) be added in series with the
lamp current feedback as shown in Figure 3.
The addition of this resistor helps minimize the
possibility of ESD damage in case of
mishandling of the IC during board level
assembly and test.
MP1026
IL
MP1026_F03
FT
Cft
Figure 3—ESD Resistor
Cft2
MP1026_F02
Figure 2—Turn Off Time Adjustment
MP1026 Rev. 1.6
9/24/2007
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2007 MPS. All Rights Reserved.
6
MP1026 – CCFL DRIVER FOR HANDHELD DISPLAY APPLICATIONS
PACKAGE INFORMATION
TSSOP20F
0.0256(0.650)TYP
0.004(0.090)
0.010(0.250)
GATE PLANE
0.105 (2.67)
0.118 (3.00)
pad width
0.169
0.177
0.244
0.260
(4.300)
(4.500)
(6.200)
(6.600)
0.004(0.090)
0o-8o
0.018(0.450)
0.030(0.750)
DETAIL "A"
0.039(1.000)REF
0.030(0.750)
SEE DETAIL "B"
PIN 1
IDENT.
0.150 (3.80)
0.165 (4.19)
pad length
0.030(0.750)
SEE DETAIL "A"
0.252 (6.400)
0.260 (6.600)
0.075(0.190)
0.012(0.300)
0.032(0.800)
0.041(1.050)
0.047(1.200)
max
0.007(0.190)
0.012(0.300)
SEATING PLANE
0.002(0.050)
0.006(0.150)
NOTE:
1) Control dimension is in inches. Dimension in bracket is millimeters.
0.004(0.090)
0.008(0.200)
0.004(0.090)
0.006(0.160)
0.007(0.190)
0.010(0.250)
DETAIL "B"
NOTICE: The information in this document is subject to change without notice. Please contact MPS for current specifications.
Users should warrant and guarantee that third party Intellectual Property rights are not infringed upon when integrating MPS
products into any application. MPS will not assume any legal responsibility for any said applications.
MP1026 Rev. 1.6
9/24/2007
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2007 MPS. All Rights Reserved.
7
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