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Электронный компонент: AN8041S

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Voltage Regulators
1
AN8041S
Liquid crystal backlight control IC
s
Overview
The AN8041S is an inverter control IC for liquid
crystal backlight using PWM method. The output
voltage of DC-DC converter and the current of cath-
ode-ray tube can be controlled by using two error
amplifiers, so that the system is designed easily.
Since the n-channel MOSFET can be directly
driven, it is possible to construct a highly effective
power supply.
s
Features
Operating supply voltage: 3.6 V to 34 V
*
Totem pole output circuit: Output current of
500 mA
Built-in bootstrap circuit
N-channel power MOSFET can be directly driven
Built-in two error amplifier circuits allow both the
voltage and current control
Incorporating on/off functions (active-high control input, standby mode current is 5
A or less)
Built-in timer latch short-circuit protection circuit
Maximum oscillation frequency: 500 kHz
Note) *: The voltage is limited to the range of 3.6 V to 17 V if used in a step-down circuit.
s
Applications
LCD displays, digital still cameras, and PDAs
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Block Diagram
SOP016-P-0225A
Unit: mm
0.3
(0
to 10
)
(0.15)
Seating plane
10.10.3
4.20.3
6.50.3
1
8
16
9
1.27
(0.605)
Seating plane
0.400.25
0.10.1
1.50.2
CB
14
Out
13
FB1
8
IN
+
1
6
IN
-
1
7
S.C.P.
5
Off
16
DTC
4
V
REF
1
GND
12
S.C.P.
comp.
Q
Q
R
S
V
CC
15
Bootstrap
CT
3
Constant
current source
RT
2
OSC
V
REF
2.57 V
On/off
active-high
PWM comp.
Error amp. 2
U.V.L.O.
Q
R
S
Latch
Error amp. 1
FB2
9
IN
+
2
11
IN
-
2
10
2
AN8041S
Voltage Regulators
s
Pin Descriptions
s
Absolute Maximum Ratings
Parameter
Symbol
Rating
Unit
Supply voltage
V
CC
35
V
Off terminal application voltage
V
OFF
35
V
Error amplifier input voltage
V
I
-
0.3 to V
REF
V
DTC terminal application voltage
V
DTC
-
0.3 to V
REF
V
Out terminal application voltage
V
OUT
35
V
CB terminal application voltage
V
CB
35
V
Out terminal constant output current
I
O
100
mA
Out terminal peak output current
I
O(PEAK)
500
mA
Power dissipation
*
P
D
143
mW
Operating ambient temperature
*
T
opr
-
30 to
+
85
C
Storage temperature
*
T
stg
-
40 to
+
125
C
s
Recommended Operating Range
Parameter
Symbol
Range
Unit
Supply voltage (when using step-down circuit)
V
CC
3.6 to 17
V
Supply voltage (when using step-up circuit)
V
CC
3.6 to 34
V
Oscillation frequency
f
OUT
5 to 500
kHz
Oscillator timing resistance
R
T
5.1 to 30
k
Oscillator timing capacitance
C
T
100 to 10 000
pF
Error amplifier input voltage
V
IN
-
0.1 to
+
0.8
V
Reference voltage output current
I
REF
-
1 to 0
mA
Pin No. Symbol
Description
1
V
REF
Reference voltage output pin
2
RT
Pin for connecting oscillator
timing resistor
3
CT
Pin for connecting oscillator
timing capacitor
4
DTC
Dead-time control pin
5
S.C.P.
Pin for connecting the time constant
setting capacitor for short-circuit
protection
6
IN
+
1
Error amplifier 1 noninverted input pin
Pin No. Symbol
Description
7
IN
-
1
Error amplifier 1 inverted input pin
8
FB1
Error amplifier 1 output pin
9
FB2
Error amplifier 2 output pin
10
IN
-
2
Error amplifier 2 inverted input pin
11
IN
+
2
Error amplifier 2 noninverted input pin
12
GND
Grounding pin
13
Out
Output pin
14
CB
Bootstrap output circuit
15
V
CC
Power supply voltage application pin
16
Off
On/off control pin
Note) *: Expect for the operating ambient temperature and storage temperature, all ratings are for T
a
=
25
C.
3
Voltage Regulators
AN8041S
s
Electrical Characteristics at V
CC
=
12 V, R
T
=
15 k
, C
T
=
120 pF, T
a
=
25
C
Parameter
Symbol
Conditions
Min
Typ
Max
Unit
Reference voltage block
Output voltage
V
REF
I
REF
=
-
1 mA
2.483
2.57
2.647
V
Input regulation with input fluctuation
Line
V
CC
=
3.6 V to 34 V
7
25
mV
Load regulation
Load
I
REF
=
-
0.1 mA to
-
1 mA
1
10
mV
Output voltage
V
TC1
T
a
=
-
30
C to
+
25
C
1
%
temperature characteristics 1
Output voltage
V
TC2
T
a
=
25
C to 85
C
1
%
temperature characteristics 2
Output short-circuit current
I
OS
-
10
mA
U.V.L.O. block
Circuit operation start voltage
V
UON
2.8
3.1
3.4
V
Hysteresis width
V
HYS
60
140
220
mV
Error amplifier block
Input offset voltage
V
IO
-
6
6
mV
Input bias current
I
B
-
500
-
25
nA
Common-mode input voltage range
V
ICR
-
0.1
0.8
V
High-level output voltage 1
V
EH
V
REF
-
0.3 V
REF
-
0.1
V
Low-level output voltage 1
V
EL
0.1
0.3
V
Output sink current
I
SINK
V
FB
=
0.9 V
8
mA
Output source current
I
SOURCE
V
FB
=
0.9 V
-
110
A
Open-loop gain
A
G
70
dB
Dead-time control circuit block
Input current
I
DTC
R
T
=
15 k
-
14.8
-
12.3
-
9.8
A
Low-level input threshold voltage
V
DT-L
Duty
=
0%
0.45
0.65
V
High-level input threshold voltage
V
DT-H
Duty
=
100%
1.2
1.4
V
Output block
Oscillation frequency
f
OUT
R
T
=
15 k
,
180
200
220
kHz
C
T
=
120 pF
Output duty ratio
Du
R
DTC
=
75 k
45
50
55
%
Low-level output voltage
V
OL
I
O
=
70 mA
1.0
1.3
V
High-level output voltage
V
OH
I
O
= -
70 mA
V
CB
-
2.0 V
CB
-
1.0
V
Frequency
f
dV
f
OUT
=
200 kHz,
3
V
supply voltage characteristics
V
CC
=
3.6 V to 34 V
Frequency
f
dT1
f
OUT
=
200 kHz,
9
V
temperature characteristics 1
T
a
= -
30
C to
+
25
C
Frequency
f
dT2
f
OUT
=
200 kHz,
9
V
temperature characteristics 2
T
a
=
25
C to 85
C
4
AN8041S
Voltage Regulators
s
Electrical Characteristics at V
CC
=
12 V, R
T
=
15 k
, C
T
=
120 pF, T
a
=
25
C (continued)
Parameter
Symbol
Conditions
Min
Typ
Max
Unit
Bootstrap circuit block
Input standby voltage
V
INCB
I
CB
=
-
70 mA
V
CC
-
1.2 V
CC
-
1.0 V
CC
-
0.8
V
Oscillator block
RT terminal voltage
V
RT
0.37
V
Short-circuit protection block
Input threshold voltage
V
THPC
0.70
0.75
0.80
V
Input standby voltage
V
STBY
30
120
mV
Input latch voltage
V
IN
30
120
mV
Charge current
I
CHG
-
2.76
-
2.3
-
1.84
A
Comparator threshold voltage
V
THL
1.82
V
On/off control block
Threshold voltage
V
TH
0.8
2.0
V
Whole device
Total consumption current
I
CC
3.9
5.0
mA
Standby current
I
CC(SB)
5
A
Pin No.
Equivalent circuit
Description
I/O
1
V
REF
:
O
The reference voltage output terminal
(2.57 V (allowance:
3%)).
Incorporating short-circuit protection against
GND.
2
RT:
The terminal used for connecting a timing resis-
tor to set oscillator's frequency.
Use a resistance value within the range of 5.1 k
to 30 k
.
The terminal voltage is approx. 0.37 V.
3
CT:
The terminal used for connecting a timing ca-
pacitor to set oscillator's frequency.
Use a capacitance value within the range of 100
pF to 10 000 pF.
For frequency setting method, refer to the
" Application Notes, [3] Function descriptions "
section. Use an oscillation frequency in the range
of 5 kHz to 500 kHz.
s
Terminal Equivalent Circuits
V
CC
1
V
REF
RT (
0.37 V)
100
2
DTC S.C.P.
V
REF
OSC
comp.
To PWM input
I
O
3
2I
O
5
Voltage Regulators
AN8041S
Pin No.
Equivalent circuit
Description
I/O
4
DTC:
The terminal for connecting a resistor and ca-
pacitor to set the dead-time and soft start period
of PWM output. Input current I
DTC
is determined
by the timing resistor R
T
, so that dispersion and
fluctuation with temperature are suppressed. It
is approx.
-
12.3
A when R
T
=
15 k
.
I
DTC
=
V
RT
1
[A]
R
T
2
5
S.C.P.:
The terminal for connecting a capacitor to set the
time constant of soft start and timer latch short-
circuit protection circuit.
Use a capacitance value in the range of more than
1 000 pF.
The charge current I
CHG
is determined by the
timing resistor R
T
, so that dispersion and fluc-
tuation with temperature are suppressed. It is
approx.
-
1.3
A when R
T
=
15 k
.
I
CHG
=
V
RT
1
[A]
R
T
11
6
IN
+
1:
I
The noninverted input terminal of the error am-
plifier 1.
For common-mode input, use in the range of
-
0.1 V to
+
0.8 V.
7
IN
-
1:
I
The inverted input terminal of the error ampli-
fier 1.
For common-mode input, use in the range of
-
0.1 V to
+
0.8 V.
8
FB1:
O
The output terminal of the error amplifier 1.
Source current : approx.
-
120
A
Sink current
: approx. 8 mA
Correct the frequency characteristics of the gain
and the phase by connecting a resistor and a ca-
pacitor between this terminal and IN
-
1 terminal.
9
FB2:
O
The output terminal of the error amplifier 2.
Source current : approx.
-
120
A
Sink current
: approx. 8 mA
Correct the frequency characteristics of the gain
and the phase by connecting a resistor and a ca-
pacitor between this terminal and IN
-
2 terminal.
s
Terminal Equivalent Circuits (continued)
Q
S
Latch
0.75 V
R
V
REF
I
CHG
To U.V.L.O.
5
V
REF
6
7
V
REF
8
Source current
Sink current
V
REF
9
Source current
Sink current
V
REF
PWM
comparator
input
I
DTC
C
DTC
R
DTC
4
RT