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PDF MAX8631Y Data sheet ( Hoja de datos )
| Número de pieza | MAX8631Y | |
| Descripción | White LED Charge Pump | |
| Fabricantes | Maxim Integrated Products | |
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19-3688; Rev 2; 5/06
EVAALVUAAILTAIOBNLEKIT
1x/1.5x/2x White LED Charge Pump with
Two LDOs in 4mm x 4mm Thin QFN
General Description
The MAX8631X/Y charge pump drives up to eight white
LEDs with regulated constant current for uniform inten-
sity. The main group of LEDs (M1–M4) can be driven
up to 30mA per LED for backlighting. The flash group
of LEDs (F1–F4) is independently controlled and can be
driven up to 100mA per LED (or 400mA total). Two
200mA LDOs are on-board to provide power for cam-
era functions. The LDOs’ output voltages are pin-pro-
grammable to meet different camera-module
requirements. By utilizing adaptive 1x/1.5x/2x charge-
pump modes and very-low-dropout current regulators,
the MAX8631X/Y achieves high efficiency over the full
1-cell lithium-battery voltage range. The 1MHz fixed-fre-
quency switching allows for tiny external components,
and the regulation scheme is optimized to ensure low
EMI and low input ripple.
The MAX8631X/Y is available in a 28-pin thin QFN,
4mm x 4mm lead-free package (0.8mm max height).
Applications
Camera Phones and Smartphones
Backlighting and Flash
PDAs, Digital Cameras, and Camcorders
Features
♦ Powers Up to 8 LEDs
Up to 30mA/LED Drive for Backlight
Up to 400mA Total Drive for Flash
♦ Two Internal Low-Noise 200mA LDOs
♦ 94% Max/85% Avg Efficiency (PLED/PBATT) over Li+
Battery Discharge
♦ 0.2% Typical LED Current Matching
♦ Adaptive 1x/1.5x/2x Mode Switchover
♦ Flexible Brightness Control
Single-Wire Serial Pulse Interface (32 Steps)
2-Bit Logic (Three Levels)
♦ Thermal TA Derating Function
♦ Low Input Ripple and EMI
♦ 2.7V to 5.5V Supply Voltage Range
♦ Soft-Start, Overvoltage, and Thermal-Shutdown
Protection
♦ 28-Pin Thin QFN, 4mm x 4mm Package
Typical Operating Circuit
1µF 1µF
INPUT
2.7V TO 5.5V
10µF
MAIN ON/OFF
AND DIMMING
FLASH ON/OFF
DUAL-LDO ON/OFF
DUAL-LDO
VOLTAGE
SELECTION
C1P C1N C2P C2N
PIN OUT
IN
OUTPUT
UP TO 480mA
10µF MAIN
FLASH
GND
PGND
MAX8631X/Y
ENM1
ENM2
ENF
ENLDO
P1
M1
M2
M3
M4
F1
F2
F3
F4
LDO1
LDO2
P2
SETM SETF
REF
0.01µF
1µF
CAMERA
MODULE
1µF
Ordering Information
PART
MAX8631XETI+
TEMP RANGE
-40°C to +85°C
MAX8631YETI+ -40°C to +85°C
*EP = Exposed paddle.
+Denotes lead-free package.
PIN-PACKAGE
28 Thin QFN-EP*
4mm x 4mm (T2844-1)
28 Thin QFN-EP*
4mm x 4mm (T2844-1)
Pin Configuration appears at end of data sheet.
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
1 page  
1x/1.5x/2x White LED Charge Pump with
Two LDOs in 4mm x 4mm Thin QFN
Typical Operating Characteristics (continued)
(VIN = VEN_ = 3.6V, circuit of Figure 1, TA = +25°C, unless otherwise noted.)
BATTERY CURRENT vs. SUPPLY
VOLTAGE DRIVING FLASH
900
800
700
600 IFLASH = 400mA
500
400 IFLASH = 160mA
300
IFLASH = 80mA
200
100
0
2.7 3.0 3.3 3.6 3.9 4.2
SUPPLY VOLTAGE (V)
INPUT RIPPLE VOLTAGE vs. SUPPLY
VOLTAGE WITH FLASH AND MAIN LEDs
10
9 FOUR MAIN LEDs AT 15mA EACH
8 IFLASH = 10mA
7 IFLASH = 40mA
6 IFLASH = 100mA
5
4
3
2
1
0
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
SUPPLY VOLTAGE (V)
LDO GROUND PIN SUPPLY
CURRENT vs. SUPPLY VOLTAGE
160
VENM = VENF = 0V, VENLDO = VIN
150
140
130 NO LOAD, BOTH LDOs 150mA, BOTH LDOs
120
110
100
90
80
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
SUPPLY VOLTAGE (V)
LED CURRENT MATCHING vs. SUPPLY
VOLTAGE WITH FOUR MAIN LEDs
16.0
15.8
15.6
15.4
15.2
15.0
14.8
14.6
14.4
14.2
14.0
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
SUPPLY VOLTAGE (V)
INPUT RIPPLE VOLTAGE vs. SUPPLY
VOLTAGE WITH FOUR MAIN LEDs
1.2
1.0 ILED = 15mA
0.8
0.6
ILED = 4.5mA
0.4
ILED = 1.5mA
0.2
0
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
SUPPLY VOLTAGE (V)
LED CURRENT MATCHING vs. SUPPLY
VOLTAGE WITH FOUR FLASH LEDs
102.0
101.5
101.0
100.5
100.0
99.5
99.0
98.5
98.0
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
SUPPLY VOLTAGE (V)
LED CURRENT vs. AMBIENT
TEMPERATURE WITH FOUR MAIN LEDs
70
60
50
40
30
20
10
0
-40
-15 10 35 60
AMBIENT TEMPERATURE (°C)
85
450
400
350
300
250
200
150
100
50
0
-40
LED CURRENT vs. AMBIENT
TEMPERATURE WITH FLASH
-15 10 35 60
AMBIENT TEMPERATURE (°C)
85
INDIVIDUAL MAIN LED CURRENT
vs. RSETM
100
10
1
1 10 100
RSETM (kΩ)
_______________________________________________________________________________________ 5
5 Page 
1x/1.5x/2x White LED Charge Pump with Two
LDOs in 4mm x 4mm Thin QFN
INITIAL tHI
0 ≥ 200µs
1 23 4 5
ENM1 AND ENM2
OR
ENF
IM_ OR IF_
tSOFT-START
32/32
31/32
30/32
tLO
500ns TO 250µs
29/32 28/32 27/32
SHUTDOWN
Figure 2. ENM_ and ENF Timing Diagram
Thermal Shutdown
The MAX8631X/Y includes a thermal-limit circuit that
shuts down the IC at approximately +160°C. Turn-on
occurs after the IC cools by approximately 20°C.
Applications Information
Setting the Main Output Current
SETM controls M1–M4 regulation current. Current flow-
ing into M1, M2, M3, and M4 is a multiple of the current
flowing out of SETM:
IM1 = IM2 = IM3 = IM4 = K x (0.6V / RSETM)
where K = 23, 69, or 230 (depending upon the state of
ENM1 and ENM2; see Table 1), and RSETM is the resis-
tor connected between SETM and GND (see the
Typical Operating Circuit).
Table 1. ENM1/ENM2 States
ENM1/ENM2 STATES BRIGHTNESS
ENM1 = low, ENM2 = low
ENM1 = low, ENM2 = high
ENM1 = high, ENM2 = low
ENM1 = high, ENM2 = high
Shutdown
1/10 brightness
3/10 brightness
Full brightness
M1–M4
CURRENT
0
23 x ISETM
69 x ISETM
230 x ISETM
Setting the Flash Output Current
SETF controls the F1–F4 regulation current. Current
flowing into F1, F2, F3, and F4 is a multiple of the cur-
rent flowing out of SETF.
IF1 = IF2 = IF3 = IF4 = N x (0.6V / RSETF)
where N = 690.
Single-Wire Pulse Dimming
For more dimming flexibility or to reduce the number of
control traces, the MAX8631X/Y supports serial pulse
dimming. Connect ENM1 and ENM2 together to enable
single-wire pulse dimming of the main LEDs (or ENF
only for single-wire pulse dimming of the flash LEDs).
When ENM1 and ENM2 (or ENF) go high simultaneous-
27 28 29 30 31 32
tHI
≥500ns
tSHDN
32/32 31/32 2ms (typ)
5/32 4/32 3/32 2/32 1/32
SHUTDOWN
ly, the main (or flash) LEDs are enabled at full bright-
ness. Each subsequent low-going pulse (500ns to
250µs pulse width) reduces the LED current by 3.125%
(1/32), so after one pulse the LED current is 96.9% (or
31/32) x ILED. The 31st pulse reduces the current to
0.03125 x ILED. The 32nd pulse sets the LED current
back to ILED. Figure 2 shows a timing diagram for sin-
gle-wire pulse dimming. Because soft-start is longer
than the initial tHI, apply dimming pulses quickly upon
startup (after initial tHI) to avoid LED current transition-
ing through full brightness.
Simple On/Off Control
If dimming control is not required, connect ENM1 to
ENM2 for simple on/off control. Drive both ENM1 and
ENM2 to a logic-level high to turn on the main LEDs.
Drive both ENM1 and ENM2 to a logic-level low to turn
off the main LEDs. ENF is the simple on/off control for
the flash LEDs. Drive ENF to a logic-level high to turn
on the flash LEDs. Drive ENF to a logic-level low to turn
off the flash LEDs. In this case, LED current is set by
the values of RSETM and RSETF.
Dimming Using PWM into ENM1
Use ENM2 for shutdown and drive ENM1 with a PWM
signal. LED brightness can be varied from 10% to full
brightness based upon the duty cycle of the PWM sig-
nal. Drive ENM2 high to keep the IC on, eliminating any
soft-start delay that would impede PWM control and
allowing a PWM frequency up to 5kHz (Figure 3).
Driving Fewer than 8 LEDs
When driving fewer than 8 LEDs, two different connec-
tion schemes can be used. The first scheme is shown
in Figure 4 where LED drivers are connected together.
This method allows increased current through the LED
and effectively allows total LED current to be ILED multi-
plied by the number of connected drivers. The second
method of connection is shown in Figure 5 where stan-
dard white LEDs are used and fewer than 8 are con-
nected. This scheme does not alter current through
each LED but ensures that the unused LED driver is
properly disabled.
______________________________________________________________________________________ 11
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet MAX8631Y.PDF ] | |
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