Analogic AAT3193IJQ-2 Low-cost, 2-/3-channel charge-pump led driver Datasheet

AAT3192/93
Low-Cost, 2-/3-Channel
Charge-Pump LED Drivers
General Description
Features
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 optimal LED current accuracy and matching.
•
•
•
•
The AAT3192/93 charge pump’s 1x mode (bypass
mode) has very low resistance allowing LED current 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.
•
•
•
•
•
•
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
Applications
•
•
•
•
Low-cost
Low-cost
Low-cost
Low-cost
Cordless Phone Handsets
Digital Cameras
Mobile Phone Handsets
MP3 and PMP Players
Typical Application
Input Voltage
2.7V to 5.5V
Input Voltage
2.7V to 5.5V
IN
C+
C IN
1μF
CP
1μF
AAT3192-1
C-
EN/SET
S 2Cwire
Interface
IN
C+
OUT
EN/SET
D1
C OUT
1μF
C IN
1μF
WLEDs
OSRAM LW M 678
or equivalent
CP
1μF
EN/SET
S 2Cwire
Interface
EN/SET
3193.2007.05.1.0
D1
D2
RSET
GND
R SET
14.3kΩ
COUT
1μF
WLEDs
OSRAM LW M 678
or equivalent
C-
D2
RSET
OUT
AAT3193-1
D3
GND
R SET
14.3kΩ
1
AAT3192/93
Low-Cost, 2-/3-Channel
Charge-Pump LED Drivers
Pin Descriptions
Symbol
Pin
AAT3192
AAT3193
1
N/C
D1
Description
AAT3192: No connection.
2
OUT
3
C-
4
C+
5
IN
AAT3193: LED1 current sink input. D1 is the input of LED1 current sink. Connect LED1’s
anode to OUT and its cathode to D1.
Charge pump output. OUT is the output of the charge pump. Bypass OUT to GND with
a 1μF or larger ceramic capacitor.
Charge pump capacitor negative node.
Charge pump capacitor positive node. Connect a 1μF ceramic capacitor between C+
and C-.
Power source input. Connect IN to the power source, typically the battery. Bypass IN to
GND with a 1μF or larger ceramic capacitor.
EN/SET
(AAT3192/93-1/
-2/-3)
LED enable and serial control input. EN/SET is the ON/OFF control for the LED and the
S2Cwire digital input for the AAT3192/93-1/-2/-3 to control serially the LED brightness
according to the maximum current set by RSET.
EN/PWM
(AAT3192/93-4)
LED ON/OFF and PWM control input. This logic input controls the LED outputs for the
AAT3192/93-4. Alternatively, a PWM signal from a GPIO or an equivalent signal from a
separate controller can be used to control LED output current linearly. A PWM signal, ranging from 10% to 100% duty cycle, controls the LED current linearly between ZS and FS.
7
RSET
A 1% tolerance resistor from this pin to GND sets the maximum LED current level. For
optimal LED output current accuracy and matching in the AAT3192/93-1/-2/-4, a 14.3kΩ
resistor sets each full-scale output current to 20mA, maximum. For the AAT3192/93-3, a
10.7kΩ resistor is recommended.
8
GND
Ground. Connect this pin to the system’s ground plane.
6
9
10
D2
D3
D1
D2
AAT3192: LED2 Current Sink Input. D2 is the input of LED2 current sink. Connect
LED2’s anode to OUT and its cathode to D2.
AAT3193: LED3 Current Sink Input. D3 is the input of LED3 current sink. Connect
LED3’s anode to OUT and its cathode to D3.
AAT3192: LED1 Current Sink Input. D1 is the input of LED1 current sink. Connect
LED1’s anode to OUT and its cathode to D1.
AAT3193: LED2 Current Sink Input. D2 is the input of LED2 current sink. Connect
LED2’s anode to OUT and its cathode to D2.
Pin Configuration
AAT3192
SC70JW-10
(Top View)
N/C
OUT
CC+
IN
2
1
10
2
9
3
8
4
7
5
6
AAT3193
SC70JW-10
(Top View)
D1
D2
GND
RSET
EN/SET
D1
OUT
CC+
IN
1
10
2
9
3
8
4
7
5
6
D2
D3
GND
RSET
EN/SET
3193.2007.05.1.0
AAT3192/93
Low-Cost, 2-/3-Channel
Charge-Pump LED Drivers
Part Number Descriptions
Part Number
Interface
Current Control,
Inverting
AAT3192IJQ-1
AAT3192IJQ-2
AAT3192IJQ-3
AAT3192IJQ-4
AAT3193IJQ-1
AAT3193IJQ-2
AAT3193IJQ-3
AAT3193IJQ-4
S2Cwire
S2Cwire
S2Cwire
PWM
S2Cwire
S2Cwire
S2Cwire
PWM
16-step
8-step
4-step
Linear
16-step
8-step
4-step
Linear
Absolute Maximum Ratings1
Symbol
Description
IN, C+, C-, OUT, D1, D2, D3, and RSET Pin Voltages to GND
EN/SET or EN/PWM Pin Voltage to GND
Operating Junction Temperature Range
Maximum Soldering Temperature (at leads, 10 sec)
Value
Units
-0.3 to 6.0
-0.3 to VIN + 0.3
-40 to 150
300
V
V
°C
°C
Value
Units
625
160
mW
°C/W
Thermal Information
Symbol
PD
θJA
Description
2, 3
Maximum Power Dissipation
Maximum Thermal Resistance2
1. Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at conditions other than the operating conditions specified is not implied. Only one Absolute Maximum Rating should be applied at any one time.
2. Mounted on an FR4 circuit board.
3. Derate 6.25mW/°C above 40°C ambient temperature.
3193.2007.05.1.0
3
AAT3192/93
Low-Cost, 2-/3-Channel
Charge-Pump LED Drivers
Electrical Characteristics1
IN = EN = 3.6V; CIN = 1µF; COUT = 1µF; CCP = 1µF; RSET = 14.3kΩ; TA =-40°C to 85°C unless otherwise noted.
Typical values are at TA = 25°C.
Symbol
Description
Conditions
Input Power Supply
IN
Input Voltage Range
IIN
Input Operating Current
IIN(SHDN)
Input Shutdown Current
Charge Pump Section
IOUT
OUT Maximum Output Current
fOSC
Charge Pump Oscillator Frequency
VIN_(TH)
Charge Pump Mode Hysteresis
tOUT
Output Start-Up Time
AAT3192/93-1/-2/-4: LED Current Sink Outputs
ID_(MAX)
D1 - D3 Current Accuracy
ΔID_(MAX)
D1 - D3 Current Matching
D1 - D3 Current Accuracy
ID_(DATA15)
(AAT3192/93-1 only)
D1 - D3 Current Accuracy
ID_(DATA8)
(AAT3192/93-2 only)
D1 - D3 Current Accuracy
ID_(10%)
(AAT3192/93-4 only)
D1- D3 Charge Pump Mode
VD_(TH)
Transition Threshold
Min
Typ
2.7
EN = IN, ID1 = ID2 = ID3 =
OFF (WLED Test Mode)
EN = IN, ID1 = ID2 = ID3 = FS
Operating, ID1 = ID2 = ID3=
OPEN; IN = 5V
EN/SET or EN/PWM = GND
0.65
ID1 = ID2 = ID3= 20mA
EN/SET or EN/PWM = IN
100
0.9
115
150
Max
Units
5.5
V
5
mA
1.5
mA
4.5
mA
1
μA
1.15
250
mA
MHz
mV
μs
DATA = 1; VIN - VF = 1.5V
DATA = 1; VIN - VF = 1.5V
17.6
19.6
±3
21.6
mA
%
DATA = 15; VIN - VF = 1.5V
1.0
1.3
1.56
mA
DATA = 8; VIN - VF = 1.5V
1.0
1.3
1.56
mA
DC = 10%; VIN - VF = 1.5V
2.5
mA
ID1 = ID2 = ID3 = 20mA
150
mV
1. The AAT3192/93 are guaranteed to meet performance specification over the -40°C to 85°C operating temperature range and are
assured by design, characterization and correlation with statistical process controls.
4
3193.2007.05.1.0
AAT3192/93
Low-Cost, 2-/3-Channel
Charge-Pump LED Drivers
Electrical Characteristics1
IN = EN = 3.6V; CIN = 1µF; COUT = 1µF; CCP = 1µF; RSET = 14.3kΩ; TA =-40°C to 85°C unless otherwise noted.
Typical values are at TA = 25°C.
Symbol
Description
Conditions
Min
Typ
Max
Units
17.6
19.6
21.6
mA
AAT3192/93-3: LED Current Sink Outputs
ID_(MAX)
D1 - D3 Current Accuracy
ΔID_(MAX)
D1 - D3 Current Matching
ID_(DATA4)
D1 - D3 Current Accuracy
D1- D3 Charge Pump Mode
Transition Threshold
AAT3192/93-1/-2/-3: EN/SET and S2Cwire Control
VENH
EN Input High Threshold Voltage
VENL
EN Input Low Threshold Voltage
IEN(LKG)
EN Input Leakage Current
tEN/SET(OFF) EN/SET Input OFF Timeout
tEN/SET(LAT) EN/SET Input Latch Timeout
tEN/SET(LOW) EN/SET Input LOW Time
tENSET(H-MIN) EN/SET Minimum High Time
tENSET(H-MAX) EN/SET Maximum High Time
AAT3192/93-4: EN/PWM Current Control
VENH
EN/PWM Input High Threshold Voltage
VENL
EN/PWM Input Low Threshold Voltage
IEN(LKG)
EN/PWM Input Leakage Current
tPWM(ON)
PWM Control Turn-on Delay
tEN/PWM
EN/PWM Input OFF Timeout
fPWM
PWM Control Frequency
VD_(TH)
RSET = 10.7kΩ; DATA = 1;
VIN - VF = 1.5V
RSET = 10.7 kΩ; DATA = 1;
VIN - VF = 1.5V
RSET = 10.7kΩ; DATA = 4;
VIN - VF = 1.5V
RSET = 10.7kΩ;
ID1 = ID2 = ID3 = 20mA
±3
0.72
0.9
%
1.1
150
mV
1.4
EN/SET = IN = 5V
0.4
1
500
500
75
-1
0.3
50
75
1.4
EN/PWM = IN = 5V
0.4
1
-1
2
0.15
Duty Cycle = 80%
mA
1
50
V
V
μA
µs
µs
µs
ns
µs
V
V
μA
µs
ms
kHz
1. The AAT3192/93 are guaranteed to meet performance specification over the -40°C to 85°C operating temperature range and are
assured by design, characterization and correlation with statistical process controls.
3193.2007.05.1.0
5
AAT3192/93
Low-Cost, 2-/3-Channel
Charge-Pump LED Drivers
Typical Characteristics
Operating Current (No Load)
vs. Input Voltage
Shutdown Current vs. Temperature
3.60
0.010
3.50
IQ (mA)
3.40
IIN(SHDN) (µA)
0.008
85°C
3.30
25°C
3.20
3.10
3.00
2.7
3.1
3.5
3.9
4.3
4.7
0.004
0.002
0°C
-45°C
0.006
5.1
0.000
-40
5.5
-15
Efficiency vs. Input Voltage
85
21.0
90%
20.5
Current (mA)
80%
Efficiency (%)
60
Current Matching vs. Temperature
100%
70%
60%
30mA
VF = 3.8V
50%
40%
30%
10mA
VF = 3.2V
20%
10%
3.1
3.5
3.9
20mA
VF = 3.5V
4.3
19.5
19.0
18.5
4.7
5.1
5.5
D2
20.0
18.0
-40
Input Voltage (V)
D3
D1
-15
10
35
60
Turn On to 2X Mode
Turn Off from 2X Mode
(20mA/ch)
(20mA/ch)
EN/SET
(2V/div)
VOUT
(2V/div)
VSINK
(2V/div)
VOUT
(1V/div)
IIN
(200mA/div)
IIN
(200mA/div)
Time (200µs/div)
85
Temperature (°C)
EN/SET
(2V/div)
6
35
Temperature (°°C)
VIN (V)
0%
2.7
10
Time (200µs/div)
3193.2007.05.1.0
AAT3192/93
Low-Cost, 2-/3-Channel
Charge-Pump LED Drivers
Typical Characteristics
Turn On to 1X Mode
Maximum LED Current vs RSET
(VIN = 4.2V; 20mA/ch)
32
EN/SET
(2V/div)
28
VF
(2V/div)
20
ILED (mA)
24
VSINK
(2V/div)
16
12
8
IIN
(200mA/div)
4
0
8
13
18
1.2
1.0
1.0
0.8
0.8
0.2
2.7
VENL (V)
VENH (V)
1.2
-40°C
85°C
0.4
0.6
-40°C
0.4
3.1
3.5
3.9
4.3
4.7
5.1
85°C
2.7
5.5
3.1
3.5
3.9
4.3
4.7
5.1
5.5
Input Voltage (V)
EN/SET Input Latch Timeout vs. Input Voltage
EN/SET Input OFF Timeout vs. Input Voltage
350
350
85°C
85°C
300
TEN/SET(OFF) (µs)
300
TEN/SET(LAT) (µs)
25°C
0.2
Input Voltage (V)
250
25°C
200
-40°C
150
100
2.7
33
EN Input Low Threshold Voltage
vs. Input Voltage
EN Input High Threshold Voltage
vs. Input Voltage
25°C
28
RSET (kΩ
Ω)
Time (200µs/div)
0.6
23
3.1
3.5
3.9
4.3
Input Voltage (V)
3193.2007.05.1.0
4.7
5.1
5.5
250
25°C
200
-40°C
150
100
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
Input Voltage (V)
7
AAT3192/93
Low-Cost, 2-/3-Channel
Charge-Pump LED Drivers
Typical Characteristics
Transition of LED Current
Transition of LED Current
(20mA to 1.3mA)
(1.3mA to 20mA)
EN
(2V/div)
EN
(2V/div)
VOUT
(1V/div)
VOUT
(1V/div)
4.0V
VSINK
(1V/div)
0.5V
4.2V
VSINK
(1V/div)
IIN
(50mA/div)
1.5V
IIN
(50mA/div)
Time (100µs/div)
Time (100µs/div)
Output Ripple Waveform
Input Current vs. Input Voltage
(2X Mode; 20mA Load)
200
VIN
(AC Coupled)
(20mV/div)
Input Current (mA)
180
VOUT
(AC Coupled)
(20mV/div)
VSINK
(AC Coupled)
(50mV/div)
160
VIN Falling
ILED = 30mA
VIN Rising
140
120
100
ILED = 20mA
80
60
40
ILED = 10mA
20
0
2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 4.7 4.9 5.1 5.3 5.5
Time (1µs/div)
8
Input Voltage (V)
3193.2007.05.1.0
AAT3192/93
Low-Cost, 2-/3-Channel
Charge-Pump LED Drivers
Functional Block Diagram
C+
C–
OUT
Two-Mode
CP Control
IN
D1
D2
VF Monitoring
3
D3
GND
IREF
EN/SET
(EN/PWM)
S2Cwire Control
(PWM Control)
Functional Description
The AAT3192 and AAT3193 are low-cost chargepump solutions designed to drive up to three white
LEDs. The charge pump operates from a 2.7V to
5.5V power source and converts it to voltage levels
necessary to drive the LEDs. LED current is individually controlled through integrated current sinks
powered from the output of the charge pump. Low
1x charge-pump output resistance and low-drop
voltage current sinks allow the charge pump to stay
in 1x mode with an input voltage as low as 3.75V
and LED forward voltages as high as 3.5V. Once
in 2x mode, the charge pump monitors the input
supply voltage and automatically switches back to
1x mode when there is sufficient input voltage.
The AAT3192/93 requires only four external components: one 1µF ceramic capacitor for the charge
pump flying capacitors (CP), one 1µF ceramic input
capacitor (CIN), one 1µF ceramic output capacitor
(COUT) and a resistor (RSET) to set the maximum LED
current. The three constant current outputs of
3193.2007.05.1.0
DAC
RSET
AAT3193 (D1 to D3) can drive three individual LEDs
with a maximum current of 30mA each. AAT3192 can
drives two constant output sinks (D1 and D2) with up
to 30mA maximum current each. AnalogicTech's
S2Cwire serial Interface enables the AAT3192/93-1/
-2/-3 and changes the current sink magnitudes
through the EN/SET pin. The AAT3192/93-4 uses an
external PWM signal to enable the IC and control the
brightness of the LEDs.
Constant Current Control using RSET
The maximum current is programmed by an external
resistor at the RSET pin. Using a 14.3kΩ external
resistor at the RSET pin, the AAT3192/93-1/-2/-4
includes an integrated serial LED current control that
sets the full-scale LED current between 20mA and
0.63mA. For the AAT3192/93-3, a 10.7kΩ external
resistor at the RSET pin sets the fu ll-scale LED current between 20mA and 1.3mA. The full-scale LED
current can set higher or lower than 20mA; see Table
5. For maximum accuracy, a 1% tolerance resistor is
recommended.
9
AAT3192/93
Low-Cost, 2-/3-Channel
Charge-Pump LED Drivers
S2Cwire Serial Interface
(AAT3192/93-1/-2/-3 only)
EN/SET held high for at least tLAT (500µs). The programmed current is then seen at the current sink
outputs. When EN/SET is held low for an amount
of time longer than tOFF (500µs), the AAT3192/93
enters into shutdown mode and draws less than
1µA from the input and the internal data register is
reset to zero.
The LED output current of AAT3192/93 is controlled by AnalogicTech's S2Cwire serial interface.
Since the LED current is programmable, no PWM
or additional control circuitry is needed to control
LED brightness. This feature greatly reduces the
burden on a microcontroller or system IC to manage LED or display brightness, allowing the user to
"set it and forget it." With its high-speed serial interface (1MHz data rate), the LED current can be
changed quickly and easily. Also the non-pulsating
LED current reduces system noise and improves
LED reliability. The S2Cwire interface relies on the
number of rising edges to the EN/SET pin to set the
register. A typical write protocol is a burst of
EN/SET rising edges, followed by a pause with
The AAT3192/93-1/2/3's serial interface reduces the
LED current on each rising pulse of the enable input.
If the AAT3192/93 is in shutdown, the first rising edge
of the EN/SET input turns on the LED driver to the
maximum current. Successive rising edges decrease
the LED current as shown in Table 1 and Figure 2 for
the AAT3192/93-1. For the AAT3192/93-2, Table 2
and Figure 3 illustrate an 8-step LED current control
profile. For the AAT3192/93-3, Table 3 and Figure 4
illustrate a 4-step LED current control profile.
THI
TLO
TOFF
TLAT
EN/SET
1
Data Reg
2
n-1
n ≤ 16
0
n-1
0
Figure 1. S2C Serial Interface Timing
D1-D3
Current (mA)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
20
18.7
17.3
16
14.7
13.3
12
10.7
9.3
8
6.7
5.3
4
2.7
1.3
0.63
20.00
Dx Output Current (mA)
Data
EN Rising
Edges
15.00
10.00
5.00
0.00
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
S2Cwire Interface Data Code
Figure 2: AAT3192/93-1 Current Control Profile
Table 1: AAT3192/93-1 LED Current Settings
10
3193.2007.05.1.0
AAT3192/93
Low-Cost, 2-/3-Channel
Charge-Pump LED Drivers
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
20
17.3
14.7
12
9.3
6.7
4
1.3
Table 2: AAT3192/93-2 LED Current Settings
Data
EN Rising
Edges
D1-D3
Current (mA)
1
2
3
4
1
2
3
4
20
13.3
6.7
0.87
Table 3: AAT3192/93-3 LED Current Settings
20.00
Dx Output Current (mA)
D1-D3
Current (mA)
15.00
10.00
5.00
0.00
1
2
3
4
5
6
7
8
2
S Cwire Interface Data Code
Figure 3: AAT3192/93-2 Current Control Profile
20.00
Dx Output Current (mA)
Data
EN Rising
Edges
15.00
10.00
5.00
0.00
1
2
3
4
2
S Cwire Interface Data Code
Figure 4: AAT3192/93-3 Current Control Profile
PWM Control (AAT3192/93-4 only)
PWM (Pulse Width Modulation) is an industry standard technique of controlling LED brightness by
modulating the conduction duty cycle of the LED
current. LED brightness is determined by the average value of the PWM signal multiplied by the LED’s
intensity where intensity is proportional to the LED
drive current. A PWM control signal can be applied
into the EN/PWM pin of the AAT3192/93-4. By
3193.2007.05.1.0
changing the duty cycle of the PWM signal from
100% (logic high) to 10%, LEDs sink current can be
programmed from 20mA to 2.4mA. To save power
when not used, AAT3192/93-4 can be shutdown by
holding the EN/PWM pin low for 1ms.
Lastly, Table 4 and Figure 5 illustrate the
AAT3192/93-4’s LED current control profile as a
function of a PWM control signal.
11
AAT3192/93
Low-Cost, 2-/3-Channel
Charge-Pump LED Drivers
EN/PWM
Duty Cycle
D1-D3
Current (mA)
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
20
17.9
15.9
14
12.1
10.1
8.2
6.3
4.3
2.4
Applications Information
LED Selection
Table 4: AAT3192/93-4 LED Current Settings
The low dropout current sinks in the AAT3192/93
maximize performance and make it capable of driving LEDs with high forward voltages. Multiple channels can be combined to obtain a higher LED drive
current without complication.
20.00
Dx Output Current (mA)
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 arrangements 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 regardless of the specific LED forward voltage (VF) levels.
15.00
10.00
Constant Current Setting
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
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)
RSET (KΩ)
30
20
15
10
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 harmonics 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
12
3193.2007.05.1.0
AAT3192/93
Low-Cost, 2-/3-Channel
Charge-Pump LED Drivers
associated with inrush currents during start-up of
the charge pump circuit.
Each of these modes will yield different efficiency
values. Refer to the following two sections for explanations for each operational mode.
Shutdown
Since the current switches are the only power
returns for all loads, there is no leakage current
when all sink switches are disabled. To activate the
shutdown operation, the EN/SET input for the
AAT3192/93-1/2/3 should be strobed low for longer
than tOFF (500μs). For the 3192/93-4 PWM options,
shutdown operation is enabled when the EN/PWM
input is strobed low longer than 1ms.In this state,
the AAT3192/93 typically draws less than 1μA from
the input. Registers are reset to 0 in shutdown.
1X Mode Efficiency
The AAT3192/93 1X mode is operational at all
times and functions alone to enhance device power
conversion efficiency when VIN is higher than the
voltage across the load. When in 1X mode, voltage
conversion efficiency is defined as output power
divided by input power.
An expression for the ideal efficiency (η) in 1X
charge-pump mode can be expressed as:
η=
Power Efficiency and Device Evaluation
V ·I
VF
POUT
= F LED ≅
PIN
VIN · IOUT
VIN
The charge pump efficiency discussion in the following sections accounts only for efficiency of the
charge pump section itself. Due to the unique circuit
architecture and design of the AAT3192/93, it is very
difficult to measure efficiency in terms of a percent
value comparing input power over output power.
-or-
Since the AAT3192/93 outputs are pure constant
current sinks and typically drive individual loads, it
is difficult to measure the output voltage for a given
output to derive an overall output power measurement. For any given application, white LED forward
voltage levels can differ, yet the output drive current will be maintained as a constant.
The AAT3192/93 contains a charge pump which
will boost the input supply voltage in the event
where VIN is less than the voltage required to supply the output. The efficiency (η) can be simply
defined as a linear voltage regulator with an effective output voltage that is equal to one and two
times the input voltage. Efficiency (η) for an ideal
2X charge pump can typically be expressed as the
output power divided by the input power.
This makes quantifying output power a difficult task
when taken in the context of comparing to other
white LED driver circuit topologies. A better way to
quantify total device efficiency is to observe the total
input power to the device for a given LED current
drive level. The best white LED driver for a given
application should be based on trade-offs of size,
external component count, reliability, operating
range, and total energy usage...not just % efficiency.
The AAT3192/93 efficiency may be quantified under
very specific conditions and is dependent upon the
input voltage versus the output voltage across the
loads applied to outputs D1 through D3 (or D2 in the
case of the AAT3192) for a given constant current
setting. Depending on the combination of VIN and
voltages sensed at the current sinks, the device will
operate in load switch mode. When any one of the
voltages sensed at the current sinks nears dropout,
the device will operate in 2X charge pump mode.
3193.2007.05.1.0
⎛ VF ⎞
η (%) = 100 · V
⎝ IN⎠
2X Charge Pump Mode Efficiency
η=
PF
PIN
In addition, with an ideal 2X charge pump, the output current may be expressed as 1/3 of the input
current. The expression to define the ideal efficiency (η) can be rewritten as:
η=
V ·I
VF
POUT
= F LED =
PIN
VIN · 2IOUT 2VIN
-or⎛ VF ⎞
η (%) = 100 · 2V
⎝ IN⎠
For a charge pump with an output of 5V and a nominal input of 3.5V, the theoretical efficiency is 71%.
13
AAT3192/93
Low-Cost, 2-/3-Channel
Charge-Pump LED Drivers
Due to internal switching losses and IC quiescent current consumption, the actual efficiency can be measured at 90%. Efficiency will decrease substantially as
load current drops below 1mA or when the voltage
level at VIN approaches the voltage level at VOUT.
Additional Applications
The current sinks of the AAT3192 and the AAT3193
can be combined to drive higher current levels
through a single LED. As an example, a single LED
can be driven at 60mA total by combining together
the D1-D3 outputs.
C2
1μF
VIN
1
2
3
4
5
C1
1μF
D1
D1
D2
OUT
D3
CGND
C+ RSET
IN EN/SET
C3
1μF
10
9
8
7
6
Capacitor Characteristics
Ceramic composition capacitors are highly recommended over all other types of capacitors for use with
the AAT3192/93. Ceramic capacitors offer many
advantages over their tantalum and aluminum electrolytic counterparts. A ceramic capacitor typically has
very low ESR, is lowest cost, has a smaller PCB footprint, and is non-polarized. Low ESR ceramic capacitors help maximizing charge pump transient response.
Since ceramic capacitors are non-polarized, they are
not prone to incorrect connection damage.
R1
14.3k
AAT3193
Equivalent Series Resistance
EN/SET
Figure 6: Higher Current, Single LED
Application.
For lower-cost applications, the flying capacitor can
be removed. This will force AAT3192/93 to operate
in 1X mode. To maintain regulated LED current, the
input supply voltage has to be higher than the
charge-pump's dropout voltage in 1X mode.
D1
D2
D3
U1
1
2
3
4
5
VIN
C3
1μF
ESR is an important characteristic to consider when
selecting a capacitor. ESR is a resistance internal to
a capacitor that is caused by the leads, internal connections, size or area, material composition, and
ambient temperature. Capacitor ESR is typically
measured in milliohms for ceramic capacitors and
can range to more than several ohms for tantalum
or aluminum electrolytic capacitors.
Ceramic Capacitor Materials
C2
1μF
D2
D1
D3
OUT
GND
CC+ RSET
IN EN/SET
AAT3193
10
9
8
7
6
R1
14.3k
EN/SET
Figure 7: Lower Cost 1X Mode Application.
Capacitor Selection
Careful selection of the three external capacitors
CIN, CP, and COUT is important because they will
affect turn-on time, output ripple, and transient per14
formance. Optimum performance will be obtained
when low equivalent series resistance (ESR)
ceramic capacitors are used; in general, low ESR
may be defined as less than 100mΩ. A value of 1μF
for all four capacitors is a good starting point when
choosing capacitors. If the constant current sinks
are only programmed for light current levels, then
the capacitor size may be decreased.
Ceramic capacitors less than 0.1μF are typically
made from NPO or C0G materials. NPO and C0G
materials generally have tight tolerance and are very
stable over temperature. Larger capacitor values are
usually composed of X7R, X5R, Z5U, or Y5V dielectric materials. Large ceramic capacitors (i.e., larger
than 2.2μF) are often available in low cost Y5V and
Z5U dielectrics, but capacitors larger than 1μF are
not typically required for AAT3192/93 applications.
Capacitor area is another contributor to ESR.
Capacitors that are physically large will have a lower
ESR when compared to an equivalent material
smaller capacitor. These larger devices can improve
circuit transient response when compared to an
equal value capacitor in a smaller package size.
3193.2007.05.1.0
AAT3192/93
Low-Cost, 2-/3-Channel
Charge-Pump LED Drivers
Evaluation Board Schematic
3
2
DC+
1
DC-
C2
1μF
VIN
J1
D1
D2
D3
JPx
GND
JP5 C1
1μF
1
2
3
4
5
C3
1μF
D1
D2
OUT
D3
CGND
C+
RSET
IN EN/SET
U1
10
9
8
7
6
R1
14.3k
AA T3193
GND
GND
R7
220
J2
R6
100K
VIN
GND
R3 R2 R1
1K 1K 1K
CYCLE
0
2
4
SW3
1
3
5
UP
0
2
4
DOWN
0
2
4
SW2
1
3
5
U2
1
2
3
4
VDD
GP5
GP4
GP3
VSS
GP0
GP1
GP2
PIC12F675
VR4
POT10K
8
7
6
5
C5
1μF
R5
330
LED7
RED
R4
330
GND
GND
SW1
1
3
5
LED0
GRN
GND
GND
Evaluation Board Layout
Figure 8: AAT3193 Evaluation Board
Top Side Layout.
3193.2007.05.1.0
Figure 9: AAT3193 Evaluation Board
Bottom Side Layout.
15
AAT3192/93
Low-Cost, 2-/3-Channel
Charge-Pump LED Drivers
Ordering Information
Package
Interface
Current Control,
Inverting
SC70JW-10
SC70JW-10
SC70JW-10
SC70JW-10
SC70JW-10
SC70JW-10
SC70JW-10
SC70JW-10
S2Cwire
S2Cwire
S2Cwire
PWM
S2Cwire
S2Cwire
S2Cwire
PWM
16-step
8-step
4-step
Linear
16-step
8-step
4-step
Linear
Marking
XGXYY
Part Number (Tape and Reel)
AAT3192IJQ-1-T1
AAT3192IJQ-2-T1
AAT3192IJQ-3-T1
AAT3192IJQ-4-T1
AAT3193IJQ-1-T1
AAT3193IJQ-2-T1
AAT3193IJQ-3-T1
AAT3193IJQ-4-T1
All AnalogicTech products are offered in Pb-free packaging. The term “Pb-free” means
semiconductor products that are in compliance with current RoHS standards, including
the requirement that lead not exceed 0.1% by weight in homogeneous materials. For more
information, please visit our website at http://www.analogictech.com/pbfree.
1. XYY = assembly and date code.
2. Sample stock is generally held on part numbers listed in BOLD.
16
3193.2007.05.1.0
AAT3192/93
Low-Cost, 2-/3-Channel
Charge-Pump LED Drivers
Package Information
SC70JW-10
1.75 ± 0.10
2.20 ± 0.20
0.40 BSC
0.225 ± 0.075
Top View
0.100
7° ± 3°
0.45 ± 0.10
4° ± 4°
0.05 ± 0.05
0.15 ± 0.05
1.10 MAX
0.85 ± 0.15
2.00 ± 0.20
2.10 ± 0.30
Side View
End View
All dimensions in millimeters.
© Advanced Analogic Technologies, Inc.
AnalogicTech cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an AnalogicTech product. No circuit patent licenses, copyrights, mask work
rights, or other intellectual property rights are implied. AnalogicTech reserves the right to make changes to their products or specifications or to discontinue any product or service without notice. Except as provided in AnalogicTech’s terms and conditions of sale, AnalogicTech assumes no liability whatsoever, and AnalogicTech disclaims any express or implied warranty relating to the sale and/or use of AnalogicTech products including liability or warranties relating to fitness for a particular purpose, merchantability, or infringement of any patent,
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customer to minimize inherent or procedural hazards. Testing and other quality control techniques are utilized to the extent AnalogicTech deems necessary to support this warranty.
Specific testing of all parameters of each device is not necessarily performed. AnalogicTech and the AnalogicTech logo are trademarks of Advanced Analogic Technologies Incorporated.
All other brand and product names appearing in this document are registered trademarks or trademarks of their respective holders.
Advanced Analogic Technologies, Inc.
830 E. Arques Avenue, Sunnyvale, CA 94085
Phone (408) 737- 4600
Fax (408) 737- 4611
3193.2007.05.1.0
17