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AAT3192 Schematic ( PDF Datasheet ) - AAT

Teilenummer AAT3192
Beschreibung (AAT3192 / AAT3193) 2-/3-Channel Charge-Pump LED Drivers
Hersteller AAT
Logo AAT Logo 




Gesamt 17 Seiten
AAT3192 Datasheet, Funktion
General Description
The AAT3192 and AAT3193 are charge-pump
based, current-sink white LED drivers capable of
driving one to three LEDs up to 30mA, each. They
automatically switch between 1x mode and 2x
mode to maintain the highest efficiency and opti-
mal LED current accuracy and matching.
The AAT3192/93 charge pump’s 1x mode (bypass
mode) has very low resistance allowing LED cur-
rent regulation to be maintained with input supply
voltage approaching the LED forward voltage.
The AAT3192 and the AAT3193 are available in a
2x2mm 10-lead SC70JW-10 packages.
AAT3192/93
Low-Cost, 2-/3-Channel
Charge-Pump LED Drivers
Features
ChargePump
• Drives up to 3 LEDs at up to 30mA, each
• Automatic Switching Between 1x and 2x Modes
• 0.9MHz Switching Frequency
• Linear LED Output Current Control
— Single-wire, S2Cwire Interface
• AAT3192/93-1: 16-step
• AAT3192/93-2: 8-step
• AAT3192/93-3: 4-step
— ON/OFF or PWM Interface
• AAT3192/93-4
• ±10% LED Output Current Accuracy
• ±3% LED Output Current Matching
• Low-current Shutdown Mode
• Built-in Thermal Protection
• Automatic Soft-start
• Available in 2x2mm SC70JW-10 Package
www.DataSheet4U.com
Typical Application
Applications
• Low-cost Cordless Phone Handsets
• Low-cost Digital Cameras
• Low-cost Mobile Phone Handsets
• Low-cost MP3 and PMP Players
Input Voltage
2.7V to 5.5V
CIN
1μF
EN/SET
S2Cwire
Interface
CP
1μF
RSET
14.3kΩ
IN
OUT
C+
AAT 3192- 1
C-
EN/SET
RSET
GND
D1
D2
C OUT
1μF
Input Voltage
2.7V to 5.5V
WLEDs
OSRAM LW M 678
or equivalent
C IN
1μF
EN/SET
S2Cwire
Interface
CP
1μF
R SET
14.3kΩ
IN
C+ OUT
AAT 3193 -1
C-
EN/SET
D1
D2
RSET
D3
GND
COUT
1μF
WLEDs
OSRAM LW M 678
or equivalent
3193.2007.05.1.0
1






AAT3192 Datasheet, Funktion
Typical Characteristics
3.60
3.50
3.40
3.30
3.20
3.10
3.00
2.7
Operating Current (No Load)
vs. Input Voltage
85°C
25°C
-45°C 0°C
3.1 3.5 3.9 4.3 4.7 5.1
VIN (V)
5.5
Efficiency vs. Input Voltage
100%
90%
80%
70%
60%
50% 30mA
40% VF = 3.8V
30%
10mA
20mA
20% VF = 3.2V VF = 3.5V
10%
0%
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
Input Voltage (V)
AAT3192/93
Low-Cost, 2-/3-Channel
Charge-Pump LED Drivers
Shutdown Current vs. Temperature
0.010
0.008
0.006
0.004
0.002
0.000
-40
-15 10
35
Temperature (°C)
60
85
Current Matching vs. Temperature
21.0
20.5
20.0
19.5
19.0
18.5
18.0
-40
D2
D1
-15
D3
10 35
Temperature (°C)
60
85
EN/SET
(2V/div)
VOUT
(2V/div)
VSINK
(2V/div)
IIN
(200mA/div)
Turn On to 2X Mode
(20mA/ch)
Time (200µs/div)
EN/SET
(2V/div)
VOUT
(1V/div)
IIN
(200mA/div)
Turn Off from 2X Mode
(20mA/ch)
Time (200µs/div)
6 3193.2007.05.1.0

6 Page









AAT3192 pdf, datenblatt
EN/PWM
Duty Cycle
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
D1-D3
Current (mA)
20
17.9
15.9
14
12.1
10.1
8.2
6.3
4.3
2.4
Table 4: AAT3192/93-4 LED Current Settings
20.00
15.00
10.00
5.00
0.00
100% 90% 80% 70% 60% 50% 40% 30% 20% 10%
EN/PWM Input Pin Duty Cycle (%)
Figure 5: AAT3192/93-4 Current Control Profile
12
AAT3192/93
Low-Cost, 2-/3-Channel
Charge-Pump LED Drivers
Applications Information
LED Selection
The AAT3192/93 is specifically intended for driving
white LEDs. However, the device design will allow
the AAT3192/93 to drive most types of LEDs with
forward voltage specifications ranging from 2.2V to
4.7V. LED applications may include mixed arrange-
ments for display backlighting, keypad display, and
any other application needing a constant current
sink generated from a varying input voltage. Since
the D1 to D3 constant current sinks are matched
with negligible supply voltage dependence, the
constant current channels will be matched regard-
less of the specific LED forward voltage (VF) levels.
The low dropout current sinks in the AAT3192/93
maximize performance and make it capable of driv-
ing LEDs with high forward voltages. Multiple chan-
nels can be combined to obtain a higher LED drive
current without complication.
Constant Current Setting
The LED current is controlled by the RSET resistor.
For maximum accuracy, a 1% tolerance resistor is
recommended. Table 5 shows the RSET resistor value
for AAT3193-1/2/4 for various LED full-scale current
levels.
ILED (mA)
30
20
15
10
RSET (KΩ)
9.53
14.3
19.1
28.7
Table 5: Maximum LED Current and RSET
Resistor Values (1% Resistor Tolerance)
for the AAT3193-1/2/4.
Device Switching Noise Performance
The AAT3192/93 operates at a fixed frequency of
approximately 1MHz to control noise and limit har-
monics that can interfere with the RF operation of
mobile communication devices. Back-injected
noise appearing on the input pin of the charge
pump is 20mV peak-to peak, typically ten times
less than inductor-based DC/DC boost converter
white LED backlight solutions. The AAT3192/93
soft-start feature prevents noise transient effects
3193.2007.05.1.0

12 Page





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