Dual High Efficiency Charge Pump White Flash Applications General Desc

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Dual High Efficiency Charge Pump White Flash Applications General Desc

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AAT2805
Dual High Efficiency Charge Pump White Flash Applications General Description
AAT2805 dual charge pump designed support both white backlight flash applications systems operating with lithium-ion/polymer batteries. backlight charge pump capable driving four LEDs total 120mA. current sinks operated individually parallel driving higher current LEDs. maximize power efficiency, charge pump operates 1.5X, mode, where mode operation automatically selected comparing forward voltage each with input voltage. AnalogicTech's AS2Cwire(Advanced Simple Serial ControlTM) serial digital input used enable, disable, current each with 16-level logarithmic scale plus four low-current settings down 50µA optimized efficiency, with typical operating quiescent current less than 50µA. flash charge pump charge pump doubler with regulated output voltage. designed deliver 120mA continuous current 250mA pulsed current. independent enable improved power savings. AAT2805 thermal protection built-in soft-start circuitry. low-current shutdown feature disconnects load from reduces quiescent current less than 1µA. AAT2805 available space-saving, thermally-enhanced TDFN44-16 package rated over -40°C +85°C temperature range.
ChargePump
Range: 2.7V 5.5V Dual Charge Pump Support Backlight Flash LEDs Backlight Charge Pump: Regulated Current Four Current Sink Inputs AS2Cwire Brightness Control Tri-Mode Charge Pump Maximum 30mA Current Input (50µA) Light Load Mode Flash Charge Pump: Regulated Output Voltage 250mA Pulsed Current Independent Backlight/Flash Control Noise 1MHz Constant Frequency Operation Automatic Soft-Start Inductors Available TDFN44-16 Package
Applications
Color (RGB) Lighting White Backlighting White Photo Flash
Typical Application
C3VOUT_FL COUT
VOUT_FLASH Flash
AAT2805
VOUT_BL
Backlight
EN/SET EN_FLSH EN/SET EN_FLSH
COUT
2805.2005.05.1.2
AAT2805
Dual High Efficiency Charge Pump White Flash Applications Descriptions
Symbol
C3C3+ VOUT_FL EN/SET C1VOUT_BL C2EN_FLSH
Function
Flying capacitor negative terminal. Flying capacitor positive terminal. Connect capacitor between C3-. Regulated output voltage flash LED. Requires capacitor connected between this ground. Input power supply. Requires capacitor connected between this ground. Current sink input Current sink input Current sink input Current sink input Ground. AS2Cwire serial interface control pin. used enable/disable backlight charge pump control brightness white LEDs. Flying capacitor positive terminal. Connect capacitor between C1-. Flying capacitor negative terminal. Regulated output voltage white LED. Requires capacitor connected between this ground. Flying capacitor positive terminal. Connect capacitor between C2-. Flying capacitor negative terminal. Enable/disable flash charge pump. Exposed paddle (bottom); connect directly beneath package.
Configuration
TDFN44-16 (Top View)
C3C3+ VOUT_FL
EN_FLSH C2C2+ VOUT_BL C1C1+ EN/SET
2805.2005.05.1.2
AAT2805
Dual High Efficiency Charge Pump White Flash Applications Absolute Maximum Ratings1
Symbol
VEN/SET; EN_FL TLEAD
Description
Input Voltage EN/SET; EN_FL Voltage Maximum Soldering Temperature leads, sec)
Value
-0.3 -0.3
Units
Thermal Information
Symbol
Description
Maximum Power Dissipation Maximum Thermal Resistance2
Value
Units
°C/W
Stresses above those listed Absolute Maximum Ratings cause permanent damage device. Functional operation conditions other than operating conditions specified implied. Only Absolute Maximum Rating should applied time. Mounted board. Derate 6.25mW/°C above 25°C. 2805.2005.05.1.2
AAT2805
Dual High Efficiency Charge Pump White Flash Applications Electrical Characteristics1
3.6V; COUT 1.0µF; -40°C 85°C unless otherwise noted. Typical values 25°C. Symbol
Description
Operation Range
Conditions
Units
4.68
Input Power Supply
Operating Current
ISHDN I(D-Match) RSINK VOUT_FL
Shutdown Current Input Current Accuracy2, Current Matching Between Current Sink Inputs2, Sink Switch Impedance (each)2 Flash Charge Pump Output Voltage Maximum Continuous IOUT Maximum Pulsed IOUT Soft-Start Time Clock Frequency Enable Threshold Enable Threshold High EN/SET Time Minimum EN/SET High Time EN/SET Timeout EN/SET Latch Timeout Enable EN/SET Input Leakage
Mode, 5.5, Active, Load Current; EN_FLSH GND, EN/SET 1.5X Mode, 5.5, Active, Load Current; EN_FLSH GND, EN/SET Mode, 5.5, Active, Load Current; EN_FLSH GND, EN/SET EN_FLSH GND, 50µA Output Setting, Mode 5.5, Load Current; EN_FLSH VIN, EN/SET EN_FLSH EN/SET ISET 30mA; 25°C VD1:D4 3.6, 3.5V
IOUT_FL FCLK VEN(L) VEN(H) TEN/SET TEN/SET TOFF TLAT
3.0V IOUT 100mA; EN_FLSH 3.0V IOUT 150mA; EN_FLSH 3.6V; VOUT 4.5V; EN_FLSH 3.6V; VOUT 4.5V; IPULSED 500mS
4.32
VEN/SET VEN/SET VEN/SET VEN/SET VEN/SET
0.6V 1.4V 0.6V 1.4V VEN_FLSH
-1.0
AAT2805 guaranteed meet performance specifications over -40°C 85°C operating temperature range assured design, characterization, correlation with statistical process controls. Specification applies only tri-mode charge pump. Specification applies only charge pump doubler. Determined active channels Current matching defined deviation sink current from average active channels.
2805.2005.05.1.2
AAT2805
Dual High Efficiency Charge Pump White Flash Applications Typical Characteristics-Flash Driver Charge Pump Section
Output Voltage Output Current
(VOUT_FL 4.5V; EN_FL VIN; EN/SET GND)
4.60
Maximum Current Pulse Supply Voltage
(VOUT_FL 4.5V; EN_FL VIN; EN/SET GND) Maximum Current Pulse (mA)
Output Voltage
One-shot pulse duration 250ms VOUT 4.0V
4.56 4.52 4.48
3.6V
3.0V
4.44
3.3V
2.7V
4.40 10.0 100.0 1000.0
Output Current (mA)
Supply Voltage
Startup Time
(50mA Load)
Startup Time
(100mA Load)
EN_FLSH (1V/div)
EN_FLSH (1V/div)
VOUT_FL (1V/div)
VOUT_FL (1V/div)
100µs/div
100µs/div
Load Response Time
(50mA Load) 3.5V VOUT_FL (10mV/div) VOUT_FL (10mV/div)
Load Response Time
(100mA Load) 3.5V
IOUT (20mA/div)
IOUT (50mA/div)
5ms/div
5ms/div
2805.2005.05.1.2
AAT2805
Dual High Efficiency Charge Pump White Flash Applications Typical Characteristics-Flash Driver Charge Pump Section
Output Ripple Voltage Time
(IOUT 50mA 3.5V) (10mV/div) VOUT (10mV/div) (10mV/div) VOUT (20mV/div)
Output Ripple Voltage Time
(IOUT 100mA 3.5V)
(10mA/div)
(10mA/div)
500ns/div
500ns/div
Supply Current Supply Voltage
IOUT VEN_FL Oscillator Frequency (MHz)
3.00 1.30
Oscillator Frequency Supply Voltage
Supply Current (mA)
2.75 2.50 2.25 2.00 1.75 1.50 1.25 1.00
1.25
+25°C
1.20
+85°C -40°C
1.15
1.10
Supply Voltage
Supply Voltage
2805.2005.05.1.2
AAT2805
Dual High Efficiency Charge Pump White Flash Applications Typical Characteristics-White Backlight Driver Section
Turn-On Mode
(VIN 4.2V; 20mA Load)
Turn-On 1.5X Mode
(VIN 3.5V; 20mA Load)
(2V/div) (2V/div) VSINK (500mV/div) (200mA/div) 100µs/div
(2V/div) (2V/div) VSINK (500mV/div) (200mA/div) 100µs/div
Turn-On Mode
(VIN 2.8V; 20mA Load) (2V/div) (1V/div)
Turn-Off from 1.5X Mode
(VIN 3.5V; 20mA Load)
(2V/div) (2V/div) VSINK (500mV/div) (200mA/div) 100µs/div
(100mA/div)
500µs/div
Efficiency Supply Voltage
4.1mA 2.9V 20.4 20.2
Current Matching Temperature
Channel Channel Channel Channel
Efficiency
Current (mA)
2.7V 10.2mA 3.1V 20mA 3.4V
20.0 19.8 19.6 19.4 19.2 19.0
Supply Voltage
Temperature (°C)
2805.2005.05.1.2
AAT2805
Dual High Efficiency Charge Pump White Flash Applications Typical Characteristics-White Backlight Driver Section
Load Characteristics
(VIN 3.7V; 1.5X Mode; 15mA Load)
Load Characteristics
(VIN 2.7V; Mode; 15mA Load)
(40mV/div) (40mV/div) VSINK (40mV/div)
(40mV/div) (40mV/div) VSINK (40mV/div)
500ns/div
500ns/div
Load Characteristics
(VIN 3.9V; 1.5X Mode; 20mA Load)
Load Characteristics
(VIN 2.9V; Mode; 20mA Load)
(40mV/div) (40mV/div) VSINK (40mV/div)
(40mV/div) (40mV/div) VSINK (40mV/div)
500ns/div
500ns/div
Load Characteristics
(VIN 4.2V; 1.5X Mode; 30mA Load) (40mV/div) (40mV/div)
Load Characteristics
(VIN 3.2V; Mode; 30mA Load)
(40mV/div) (40mV/div) VSINK (40mV/div)
VSINK (40mV/div)
500ns/div
500ns/div
2805.2005.05.1.2
AAT2805
Dual High Efficiency Charge Pump White Flash Applications Typical Characteristics-White Backlight Driver Section
EN/SET Latch Timeout Input Voltage
EN/SET Latch Timeout (µs)
EN/SET Timeout Input Voltage
EN/SET Timeout (µs)
-40°C
-40°C
25°C
85°C
25°C
85°C
Input Voltage
Input Voltage
Input Ripple Input Voltage
Enable Threshold High
Enable Threshold High Input Voltage
Amplitude (mV)
2.50 2.67 2.84 3.01 3.18 3.35 3.52 3.69 3.86 4.03 4.20
-40°C
20mA
30mA
25°C
85°C
10mA
Input Voltage
Input Voltage
Enable Threshold Input Voltage
Enable Threshold
-40°C
25°C
85°C
Input Voltage
2805.2005.05.1.2
AAT2805
Dual High Efficiency Charge Pump White Flash Applications Functional Block Diagram
Soft-Start
EN_FLSH
1MHz Oscillator
Charge Pump
VOUT_FLSH
VREF Soft-Start Control 1MHz Oscillator Voltage Reference 1.5X Charge Pump
C1C2+ C2VOUT_BL
EN/SET
Control Logic
Functional Description
AAT2805 dual charge pump designed flash white applications. backlight charge pump tri-mode load switch (1X) high efficiency (1.5X charge pump device. maximize power conversion efficiency, internal sensing circuit monitors voltage required each constant current sink input sets load switch charge pump modes based input battery voltage current sink input voltage. battery voltage discharges over time, white charge pump enabled when four current sink inputs near dropout. charge pump initially starts 1.5X mode. charge pump output drops
enough current source output become close dropout, charge pump will automatically transition mode. four constant current sink inputs drive four individual LEDs with maximum current 30mA LED. unused sink inputs must connected VOUT_BL; otherwise, part will operate only charge pump mode. AS2Cwire serial interface enables sets constant current sink magnitudes. AS2Cwire addressing allows main channels D1-D3 controlled independently from sub-channel flash charge pump charge pump doubler with regulated output voltage. designed deliver 120mA continuous current 250mA pulsed current.
2805.2005.05.1.2
AAT2805
Dual High Efficiency Charge Pump White Flash Applications
AAT2805 requires external components: three ceramic capacitors charge pump flying capacitors (C1, C3), ceramic input capacitor (CIN), 0.33µF ceramic capacitor backlight charge pump output capacitor (COUT), ceramic capacitor flash charge pump output capacitor (COUT). IOUT (mA) 30mA 15mA
30.0 26.7 23.8 21.4 19.0 16.7 15.2 13.3 11.9 10.5 15.0 13.3 11.9 10.7
Data
20mA
20.0 17.8 15.9 14.3 12.7 11.1 10.2
Constant Current Output Level Settings
constant current level channels AS2Cwire serial interface according logarithmic scale. current level spacing between adjacent constant current settings. this manner, brightness appears change linearly when settings traversed. Because inputs true independent constant current sinks, voltage observed single given input will determined difference between VOUT actual forward voltage (VF) being driven. Since constant current levels programmable, (pulse width modulation) additional control circuitry needed control brightness. This feature greatly reduces burden microcontroller system manage display brightness, allowing user "set forget it." With high-speed serial interface (>1MHz data rate), current drive changed successively brighten LEDs, smooth transitions (e.g., fade-out) abrupt steps, giving user complete programmability real-time control brightness. each Current scale (see Table there current level settings separated from another approximately 1dB. Code full-scale current Code full-scale current attenuated roughly 14dB. Code reserved current" setting. When programming charge pump, will default 20mA maximum scale. AAT2805 offers additional Current mode with reduced quiescent current (see Table This mode especially useful low-current applications where continuous, current state maintained. reduction quiescent current significantly reduces impact maintaining continuous backlighting state.
Table Constant Current Programming Levels. Data
D1-D3 (mA)
0.05 0.05
(mA)
0.05 0.05
Table Current Register Settings.
2805.2005.05.1.2
AAT2805
Dual High Efficiency Charge Pump White Flash Applications
AS2Cwire Serial Interface
Cwire single wire interface used possible combinations current levels channel states. AS2Cwire addressing capability multiple data registers. With multiple data registers, main sub-channel programmed together independently from another. AS2Cwire relies number rising edges EN/SET address load registers. AS2Cwire latches data address after EN/SET been held high time TLAT. Address data differentiated number EN/SET rising edges. Since data registers bits each, differentiating number pulses that Address signified rising edges, Address rising edges, forth. Data number rising edges between including typical write protocol burst EN/SET rising edges, signifying particular address, followed pause with EN/SET held high TLAT timeout period, burst rising edges signifying data, TLAT timeout data registers. Once address set, then multiple writes corresponding data register allowed. When EN/SET held amount time greater than TOFF, charge pump enters into shutdown mode draws less than from supply. Address default address first rising edge after charge pump been disabled. Whenever shutdown mode entered, registers reset
part programmed operate Current mode Data Addresses irrelevant. Current mode, Current register takes precedence. Current Register Settings table below current level settings main/ sub-configurations that result. EN/SET Edges
Address
Addressed Register
1&2: D1-D4 Current D1-D3 Current Current Current Current
Table Address Settings.
Current Current Registers
Current Current registers program constant current settings outside 20mA scale. default (without changing Current register), charge pump operates 20mA scale (see Table example, change 30mA scale, address Current register with rising edges pause TLAT. Program Current register with rising edges pause TLAT. part will next operate same Data row, setting found 30mA column. Next, change different setting 30mA scale, address D1-D4 register with rising edges. Program constant current level with 1-16 rising edges. part will update Data setting shown Table charge pump distinct Current mode with ultra-low quiescent current. drive currents less, part operates with significantly reduced quiescent current. This particularly useful applications requiring "always condition such transmissive displays. another example, change Current mode, address Current register with rising edges pause TLAT. Program Current register with rising edges pause TLAT. Address Current register with rising edges pause TLAT. Program Current register with 1-16 rising edges. part will update Current mode setting operate with significantly reduced quiescent current.
AS2Cwire Addressing
Five addresses available enable part's functionality (see Table 4-bit registers control main sub-channel, giving settings each. main sub-channel programmed same constant current level using Address Addresses program main sub-channel independently. Address program Current register, which sets Current scale. Lastly, Address programs Current register. Current register controls efficient Current mode. When Current register programmed changing data Addresses will result corresponding values found Table When Current register programmed
2805.2005.05.1.2
AAT2805
Dual High Efficiency Charge Pump White Flash Applications
AS2Cwire Serial Interface Timing Diagram
Address
TLAT TLAT
Data
EN/SET
Address
Data
Data
Data
Current
20mA scale 30mA scale 15mA scale Current Mode
Applications Information
Selection
AAT2805 specifically intended driving white LEDs. However, device design will allow AAT2805 drive most types LEDs with forward voltage specifications ranging from 2.0V 4.3V. applications include main display backlighting, camera photo-flash applications, color (RGB) LEDs, infrared (IR) diodes remotes, other loads benefiting from controlled output current generated from varying input voltage. Since input current sinks matched with negligible voltage dependence, brightness will matched regardless specific forward voltage (VF) levels. some instances (e.g., high-luminous-output applications such photo-flash), necessary drive high-VF type LEDs. low-dropout current-sinks AAT2805 make capable driving LEDs with forward voltages high 4.3V full current from input supply 3.0V. Outputs paralleled drive high-current LEDs without complication.
Table Maximum Current Settings Address
Disabled Current Sinks
backlight charge pump equipped with "auto-disable" feature protect against failure condition. Current sink inputs that used should disabled. disable properly terminate unused current sink inputs, they must tied VOUT. left unconnected terminated ground, part will forced operate charge pump mode. Properly terminating unused current sink inputs important prevent charge pump modes from activating prematurely. When properly terminated, only small sense current flows each disabled channel. sense current each disabled channel less than 10µA.
2805.2005.05.1.2
AAT2805
Dual High Efficiency Charge Pump White Flash Applications
Device Switching Noise Performance
AAT2805 operates fixed frequency approximately 1MHz control noise limit harmonics that interfere with operation cellular telephone handsets other communication devices. Back-injected noise appearing input charge pump 20mV peak-to-peak, typically times less than inductor-based DC/DC boost converter white backlight solutions. AAT2805 soft-start feature prevents noise transient effects associated with in-rush currents during start charge pump circuit.
Ceramic Capacitor Materials
Ceramic capacitors less than 0.1µF typically made from materials. materials typically have tight tolerance stable over temperature. Larger capacitor values typically composed X7R, X5R, Z5U, dielectric materials. Large ceramic capacitors, typically greater than 2.2µF, often available low-cost dielectrics, capacitors greater than typically required AAT2805 applications. Capacitor area another contributor ESR. Capacitors that physically large will have lower when compared equivalent material smaller capacitor. These larger devices improve circuit transient response when compared equal value capacitor smaller package size.
Capacitor Selection
Careful selection external capacitors CIN, COUT (for backlight flash) important because they will affect turn-on time, output ripple, transient performance. Optimum performance will obtained when equivalent series resistance (ESR) (<100m) ceramic capacitors used. general, defined less than 100m. value capacitors good starting point when choosing capacitors.
Thermal Protection
AAT2805 thermal protection circuit that will shut down charge pumps temperature rises above thermal limit.
Charge Pump Power Efficiency Capacitor Characteristics
Ceramic composition capacitors highly recommended over other types capacitors with AAT2805. Ceramic capacitors offer many advantages over their tantalum aluminum electrolytic counterparts. ceramic capacitor typically very ESR, lowest cost, smaller footprint, non-polarized. ceramic capacitors help maximize charge pump transient response. Since ceramic capacitors non-polarized, they prone incorrect connection damage. Backlight Charge Pump: charge pump efficiency discussion following sections only accounts efficiency charge pump section itself. unique circuit architecture, very difficult measure efficiency terms percent value comparing input power over output power. Since outputs pure constant current sinks typically drive individual loads, difficult measure output voltage given output derive overall output power measurement. given application, white forward voltage levels differ, output drive current will maintained constant. This makes quantifying output power difficult task when taken context comparing other white driver circuit topologies. better quantify total device efficiency observe total input power device given current drive level. best white driver given application should based trade-offs size, external component count, reliability, operating range, total energy usage.not just efficiency."
Equivalent Series Resistance
important characteristic consider when selecting capacitor. resistance internal capacitor, which caused leads, internal connections, size area, material composition, ambient temperature. Capacitor typically measured milliohms ceramic capacitors range more than several ohms tantalum aluminum electrolytic capacitors.
2805.2005.05.1.2
AAT2805
Dual High Efficiency Charge Pump White Flash Applications
Efficiency AAT2805 quantified under very specific conditions dependent upon input voltage versus output voltage seen across loads applied outputs through given constant current setting. Depending combination voltages sensed current sinks, device will operate load switch mode. When voltages sensed current sinks nears dropout, device will operate 1.5X charge pump mode. Each these modes will yield different efficiency values. Refer following sections explanations each operational mode. Load Switch Mode Efficiency: load switch mode operational times functions alone enhance device power conversion efficiency when greater than voltage across load. When load switch mode, voltage conversion efficiency defined output power divided input power: POUT addition, with ideal 1.5X charge pump, output current expressed input current. expression define ideal efficiency rewritten POUT VOUT IOUT VOUT 1.5IOUT 1.5VIN
-or-
VOUT 1.5VIN
expression define ideal efficiency rewritten POUT VOUT IOUT VOUT IOUT
charge pump with output volts nominal input volts, theoretical efficiency 95%. internal switching losses quiescent current consumption, actual efficiency measured 93%. These figures close agreement output load conditions from 100mA. Efficiency will decrease load current drops below 0.05mA when level approaches VOUT. Flash Charge Pump: flash charge pump regulated output voltage doubling charge pump. efficiency defined linear voltage regulator with effective output voltage that equal times input voltage. expression define ideal efficiency written POUT VOUT IOUT VOUT 2.0IOUT 2.0VIN
-or-
VOUT -orCharge Pump Mode Efficiency: Fractional charge pumps will boost input supply voltage event where less than voltage required constant current source outputs. efficiency simply defined linear voltage regulator with effective output voltage that equal half times input voltage. Efficiency ideal 1.5X charge pump typically expressed output power divided input power: POUT
VOUT 2.0VIN
charge pump with output volts nominal input volts, theoretical efficiency 83.3%. internal switching losses quiescent current consumption, actual efficiency measured approximately 82%. Efficiency will decrease level approaches that regulated VOUT. Refer device typical characteristics curves expected actual efficiency based either input voltage load current.
2805.2005.05.1.2
AAT2805
Dual High Efficiency Charge Pump White Flash Applications Ordering Information
Package
TDFN44-16
Marking1
NIXYY
Part Number (Tape Reel)2
AAT2805IXN-4.5-T1
Package Information
TDFN44-16
Index Area (D/2 E/2) Detail
4.00 0.05
3.30 0.05
0.10 0.16
0.375 0.125
0.075 0.075 Detail
View
Bottom View
Indicator (optional)
7.5° 7.5°
0.05 -0.20
0.229 0.051
Detail
Option C0.30 (4x) Chamfered corner Option R0.30 (4x) Round corner
0.05 0.05
Side View Detail
dimensions millimeters.
assembly date code. Sample stock generally held part numbers listed BOLD.
AnalogicTech cannot assume responsibility circuitry other than circuitry entirely embodied AnalogicTech product. circuit patent licenses, copyrights, mask work rights, other intellectual property rights implied. AnalogicTech reserves right make changes their products specifications discontinue product service without notice, advise customers obtain latest version relevant information verify, before placing orders, that information being relied current complete. products sold subject terms conditions sale supplied time order acknowledgement, including those pertaining warranty, patent infringement, limitation liability. AnalogicTech warrants performance semiconductor products specifications applicable time sale accordance with AnalogicTech's standard warranty. Testing other quality control techniques utilized extent AnalogicTech deems necessary support this warranty. Specific testing parameters each device necessarily performed.
Advanced Analogic Technologies, Inc.
Arques Avenue, Sunnyvale, 94085 Phone (408) 737-4600 (408) 737-4611
2805.2005.05.1.2
0.23 0.05
0.45 0.05
4.00 0.05
2.60 0.05
Form#: FOR001 Rev.

Dual High Efficiency Charge Pump White Flash Applications General Desc

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