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AAT3141 Schematic ( PDF Datasheet ) - AAT

Teilenummer AAT3141
Beschreibung High Efficiency 1X/1.5X/2X Charge Pump
Hersteller AAT
Logo AAT Logo 




Gesamt 16 Seiten
AAT3141 Datasheet, Funktion
AAT3141
High Efficiency 1X/1.5X/2X Charge Pump
for White LED Applications
General Description
Features
ChargePump
The AAT3141 is a low noise, constant frequency
charge pump DC/DC converter that uses a tri-mode
load switch (1X), fractional (1.5X), and doubling (2X)
conversion to maximize efficiency for white LED appli-
cations. The device produces current levels up to
30mA on each of its four current source outputs to
drive various arrangements of LEDs from a 2.7V to
5.5V input. Outputs may be operated individually or in
parallel for driving higher-current LEDs. A low external
parts count (two 1µF flying capacitors and two small
1µF capacitors at VIN and CP) make the AAT3141 ide-
ally suited for small battery-powered applications.
The AAT3141 is equipped with AnalogicTech’s unique
AutoBias™ technology which allows individual LEDs
to be powered either by charge pump or battery input,
determined internally and automatically to maximize
the power efficiency even with a large difference in
LED forward voltage.
• VIN Range: 2.7V to 5.5V
• Tri-Mode 1X, 1.5X, and 2X Charge Pump for
Maximum Efficiency and VF Coverage
• Drives Low-VF and High-VF Type LEDs
• Up to Four 30mA Outputs
• AS2Cwire Independent 3+1 Output Addressing
• 32-Position Logarithmic Scale with Digital
Control
• Low Noise Constant Frequency Operation
• 1MHz Switching Frequency
• AutoBias Technology
• Small Application Circuit
• Regulated Output Current
• Automatic Soft Start
• No Inductors
• IQ <1µA in Shutdown
• 12-Pin TSOPJW Package
AnalogicTech's Advanced Simple Serial Control™
(AS2Cwire™) digital input is used
and set the LED drive current with
to
a
enable,
32-level
disable,
logarith-www.DataSheet4U.com
Applications
mic scale LED brightness control. The AAT3141 has a
thermal management system to protect the device in
the event of a short-circuit condition at an output pin.
Built-in soft-start circuitry prevents excessive inrush
current during start-up. A high charge pump switching
• Color (RGB) Lighting
• Programmable Current Sources
• White LED Backlighting
• White Photo Flash for Digital Still Cameras
frequency enables the use of very small external
capacitors. In shutdown mode, the device disconnects
the load from VIN and reduces quiescent current to
less than 1µA. The AAT3141 is available in the very
small, Pb-free 12-pin TSOPJW package.
Typical Application
VBATTERY
CIN CCP
1μF 1μF
EN/SET
VIN C1+
CP C1-
C2+
AAT3141
C2-
EN/SET
D1
D2
D3
D4
GND
C1
1μF
C2
1μF
D4 D3 D2 D1
3141.2007.03.1.3
1






AAT3141 Datasheet, Funktion
AAT3141
High Efficiency 1X/1.5X/2X Charge Pump
for White LED Applications
Typical Characteristics
Unless otherwise noted, VIN = 3.5V, CIN = CCP = C1 = C2 = 1µF, TA = 25°C.
Line Response
(1X Mode, 4x19mA Load)
Line Response
(1X Mode, 4x30mA Load)
VIN
(0.5V/div)
VLED
(20mV/div)
VCP
(0.5V/div)
ID
(10mA/div)
Time (1ms/div)
VIN
(0.5V/div)
VLED
(20mV/div)
VCP
(0.5V/div)
ID
(10mA/div)
Time (1ms/div)
VIN
(0.5V/div)
VLED
(20mV/div)
VCP
(0.5V/div)
ID
(10mA/div)
Line Response
(1.5X Mode, 4x19mA Load)
Time (1ms/div)
VIN
(0.5V/div)
VLED
(20mV/div)
VCP
(0.5V/div)
ID
(10mA/div)
Line Response
(1.5X Mode, 4x30mA Load)
Time (1ms/div)
VF
(20mV/div)
IIN
(10mA/div)
VCP
(20mV/div)
Load Characteristics
(1.5X Mode, 4x15mA Load)
Time (1μs/div)
VF
(20mV/div)
IIN
(10mA/div)
VCP
(20mV/div)
Load Characteristics
(1.5X Mode, 4x30mA Load)
Time (1μs/div)
6 3141.2007.03.1.3

6 Page









AAT3141 pdf, datenblatt
AAT3141
High Efficiency 1X/1.5X/2X Charge Pump
for White LED Applications
AS2Cwire Serial Interface
The current source output magnitude is controlled
by the AS2Cwire serial digital input. AS2Cwire adds
addressing capability for multiple data registers
over the Simple Serial Control™ (S2Cwire™),
which is only capable of controlling a single regis-
ter. The AAT3141 has two registers. One contains
the current level setting for outputs D1 to D3, and
the other contains the current level setting for out-
put D4.
Three addresses are used to control the two regis-
ters. Address 0 addresses both registers simulta-
neously to allow the loading of both registers with
the same data using a single write protocol.
Address 1 addresses Register 1 for D1 to D3 cur-
rent level settings. Address 2 addresses Register
2 for D4 current level settings.
As with S2Cwire, AS2Cwire relies on the number of
rising edges of the EN/SET pin to address and load
the registers. AS2Cwire latches data or address
after the EN/SET pin has been held high for time
TLAT. Address or data is differentiated by the num-
ber of EN/SET rising edges. Since the data regis-
ters are 5 bits each, the differentiating number of
pulses is 25 or 32, so that Address 0 is signified by
33 rising edges, Address 1 by 34 rising edges and
Address 2 by 35 rising edges. Data is set to any
number of rising edges between 1 and including
32. A typical write protocol is a burst of EN/SET ris-
ing edges, signifying a particular address, followed
by a pause with EN/SET held high for the TLAT time-
out period, a burst of rising edges signifying data,
and a TLAT timeout for the data registers. Once an
address is set, then multiple writes to the corre-
sponding data register are allowed. Address 0 is
the default address on the first rising edge after the
AAT3141 has been disabled. If data is presented
on the first rising edge with no prior address, both
data registers are simultaneously loaded.
When EN/SET is held low for an amount of time
greater than TOFF, the AAT3141 enters into shutdown
mode and draws less than 1µA from VIN. Data and
address registers are reset to 0 during shutdown.
Address
0
1
2
EN/SET Rising Edges
33
34
35
Data Register
1 & 2: D1-D4
1: D1-D3
2: D4
Table 2: AS2Cwire Serial Interface Addressing.
AS2Cwire Serial Interface Timing
EN/SET
Address
THI
TLO
TLAT
12
33 34
Address
0
Data
TLAT
1 2 . . . n <= 32
1
Data Reg 1
0n
Data Reg 2
0
12 3141.2007.03.1.3

12 Page





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