AME, Inc.
AME9001
CCFL Backlight Controller
n
General Description
The AME9001 controller provides a cost efficient means
to drive single or multiple cold cathode fluorescent lamps
(CCFL). Specifically the AME9001 drives 3 external
MOSFETs that, in turn, drive a wirewound transformer
that is coupled to the CCFL.
The AME9001 includes features such as soft start, duty
cycle dimming control, and fault detection. It is designed
to work with input voltages from 7V up to 24V. When
disabled the circuit goes into a zero current mode.
For applications that use a piezoelectric transformer
please look at the AME9000.
n
Pin Configuration
24
23
22
21
20
19
18
17
16
15
14
13
AME9001
1
2
3
4
5
6
7
8
9
10
11
12
AME9001
24PIN QSOP
1. VREF
2. CE
3. SSC
4. RDELTA
5. FAULTB
6. RT2
7. VSS
8. OVP
9. CS
10.CSCOMP
11.CSDET
12.NC
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
OUTC
OUTAPB
OUTA
VBATT
VDD1
VDD
CT1
FB
COMP
BRIGHT
SSV
PNP
n
Features
l
Small package: 24 pin QSOP
l
Drives multiple tubes
l
Automatically checks for common fault
conditions
l
7.0V < Vbatt < 24V
l
Low component count
l
Low Idd < 3.5mA
l
<1uA shutdown mode
Controller
n
System Block Diagram
External
Components
CCFL Array
n
Applications
l
Notebook computers
l
LCD/TFT displays
AME
9001
LIGHT
+
Resistors
+
Capacitors
N
1
AME, Inc.
AME9001
CCFL Backlight Controller
n
Pin Description
Pin #
1
2
Pin Name
VREF
CE
Pin Description
Reference. Compensation point for the 3.4V internal voltage reference. Must
have bypass capacitor connected here to VSS.
Chip enable. When low (<0.4V) the chip is put into a low current (~0uA)
shutdown mode.
Blanking interval ramp. During the first cycle this pin sources 1
m
A. During
subsequent cycles it sources 150
m
A. This is primarily used to provide a
"blanking interval" at the beginning of every dimming cycle to temporarily disable
the fault protection circuitry. (See application notes.)
A resistor connected from this pin to VBATT modulates the switching frequency
as a function of battery voltage.
0.1
m
F cap to VSS.
A resistor from this pin to VSS sets the minimum frequency of the VCO. The
voltage at this pin is 1.5V
Negative supply. Connect to system ground.
Over voltage protection input. Indirectly senses the voltage at the secondary of
the transformer through a resistor (or capacitor) divider. It will immediately turn
the circuit off if the voltage at OVP is over 3V. It will also turn the chip off if the
voltage at OVP is less than 250mV for 4 successive clock cycles after the
voltage at SSC has risen above 3V (SSC>3V).
Negative input of the auxiliary error amplifier(EA2). In this application it is
normally shorted to CSCOMP
Output of the auxiliary error amplifier(EA2). In this application the auxiliary error
amp is in a unity gain configuration and the voltage at CSCOMP =1.25V as long
as SSC > 1.25V. Otherwise CSCOMP is clamped to the voltage at SSC.
Current sense detect. Connect this pin to the CCFL current sense resistor
divider. If this pin is below 250mV for 4 consecutive clock cycles after SSC > 3V
then the circuit will shutdown.
Must float.
Drives one of the external NFETs, opposite phase of OUTAPB.
Drives one of the external NFETs, opposite phase of OUTC.
Drives the high side PFET.
Battery input. This is the positive supply for the OUTA driver.
Must be tied to VDD.
Regulated 5V supply input.
Sets the dimming cycle frequency. Usually about 100Hz.
Negative input of the voltage control loop error amplifier.
Output of the voltage control loop error amplifier.
Brightness control input. A DC voltage on this controls the duty cycle of the
dimming cycle. This pin is compared to a 3V ramp at the CT1 pin.
Soft start ramp for the voltage control loop. (20uA source current.)
Drives the base of an external PNP transistor used for the 5V LDO.
3
SSC
4
5
6
7
RDELTA
FAULTB
RT2
VSS
8
OVP
9
10
CS
CSCOMP
11
12
13
14
15
16
17
18
19
20
21
22
23
24
2
CSDET
NC
OUTC
OUTAPB
OUTA
VBATT
VDD1
VDD
CT1
FB
COMP
BRIGHT
SSV
PNP
AME, Inc.
AME9001
CCFL Backlight Controller
n
Ordering Information
Part Number
AME9001AETH
Marking
AME9001AETH
xxxxxxxxHN
yyww
Output Voltage
N/A
Package
QSOP-24
Operating Temp. Range
- 40
o
C to + 85
o
C
" xxxxxxxx HN " for Internal code
n
Absolute Maximum Ratings
Parameter
Battery Voltage (VBATT)
ESD Classification
Maximum
25
B
Unit
V
Caution: Stress above the listed absolute maximum rating may cause permanent damage to the device
n
Recommended Operating Conditions
Parameter
Battery Voltage (VBATT)
Ambient Temperature Range
Junction Temperature
Rating
7 - 24
- 40 to + 85
- 40 to + 125
Unit
V
o
C
C
o
n
Thermal Information
Parameter
Thermal Resistance (QSOP - 24)
Maximum Junction Temperature
Maximum Lead Temperature (10 Sec)
Maximum
325
150
300
Unit
o
C/W
o
C
C
o
3
AME, Inc.
AME9001
CCFL Backlight Controller
n
Electrical Specifications
TA= 25
O
C unless otherwise noted, VBATT = 15V, CT1 = 0.01uF, RT2 = 56K
Parameter
5V supply (VSUPPLY)
Output voltage
Line regulation
Load regulation
Temperature drift
3.4V reference (VREF)
Initial voltage
Line regulation
Temperature drift
V
REF
V
REFLINE
V
REFTC
Vbatt = 15V, Iref = 0
7< Vbatt < 24V
-10C <Ta < 70C
3.25
-0.1
100
3.4
3.525
0.1
V
%
ppm/C
V
DD
V
DDLINE
V
DDLOAD
V
DDTC
7<Vbatt<24
Vbatt=7V, 0mA < Iload < 25mA
-10C < Ta < 70C
4.9
-0.5
-0.2
0.5
5.15
5.35
0.5
0.2
V
%
%
%
Symbol
Test Condition
Min
Typ
Max
Units
Brightness oscillator (CT1, BRIGHT)
Ramp amplitude
Frequency
Line regulation
Temperature drift
Comparator offset
Vco oscillator (RT2, RDELTA)
Initial frequency
Line regulation
Temperature drift
VCO pullin range
F
VCO(OUTA)
LINE
VCO
TC
VCO
PULL
VCO
RT2 = 56k
7< Vbatt < 24V
-10C < Ta < 70C
47
-0.8
+-0.5
RT2/(RDELTA X 5)
52
0.8
kHz
%
%
%
V
CT1
F
CT1
LINE
CT1
TC
CT1
VOS
CT1
7< Vbatt < 24V
-10C < Ta < 70C
70
-0.5
=+-3
10
3
130
0.5
V
Hz
%
%
mV
Error amplifiers (FB, COMP, CS, CSCOMP)
Offset voltage, WRT Vref
Input bias current
Input offset current
Open loop gain
Unity gain frequency
Output high voltage (comp)
Output low voltage
Output high voltage (cscomp)
V
OS
I
B
I
OS
A
OL
F
T
V
OH
V
OL
V
OH
I
SOURCE
= 50uA
I
SINK
= 500uA
I
SOURCE
= 50uA
4.77
3.39
0.4
-40
1
1
70
1
40
mV
nA
nA
dB
Mhz
V
V
V
4
AME, Inc.
AME9001
CCFL Backlight Controller
n
Electrical Specifications(contd.)
TA= 25
O
C unless otherwise noted, VBATT = 15V, CT1=0.01uF, RT2 = 56K
Parameter
Output A (OUTA)
Peak current
Output Low Voltage
Output High Voltage
Other outputs (OUTAPB, OUTC)
Peak current
Output Low Voltage
Output High Voltage
Soft start clamps (SSC, SSV)
Initial SSC current
Normal SSC current
SSV current
Other parameters
CE high threshold
CE low threshold
OVP high threshold
OVP low threshold
CSDET threshold
Average supply current
Average off current
CE
HIGH
CE
LOW
OVP
HI
OVP
LO
V
THCS
I
BATT
I
OFF
No FET gate current
In the application
3.2
200
200
2.5
1.5
0.4
3.55
300
300
6
10
V
V
V
mV
mV
mA
uA
I
SSCINIT
I
SSC
I
SSV
0.4
107
13
1.2
180
25
uA
uA
uA
I
PEAKBC
V
OL
V
OH
I
SINK
= 10mA
I
SOURCE
= 10mA
VDD - .7
1
0.25
Amp
V
V
I
PEAKA
V
OL
V
OH
0.2mA
-5mA
14.4
1
10.8
Amp
V
V
Symbol
Test Condition
Min
Typ
Max
Units
5
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