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PDF MAX8831 Data sheet ( Hoja de datos )
| Número de pieza | MAX8831 | |
| Descripción | High Efficiency White LED Step-Up Converter | |
| Fabricantes | Maxim Integrated Products | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de MAX8831 (archivo pdf) en la parte inferior de esta página. Total 27 Páginas | ||
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19-4370; Rev 0; 11/08
www.DataSheet4U.com
EVALUATION KIT
AVAILABLE
High-Efficiency, White LED Step-Up Converter
with I2C Interface in 2mm x 2mm WLP
General Description
The MAX8831 integrates a 60mA, 28V PWM DC-DC
step-up converter with five low-dropout LED current
regulators for display and keypad backlighting in cell
phones, PDAs, and other portable devices. The IC pro-
vides up to 90% efficiency over the entire input voltage
range of 2.7V to 5.5V. The step-up converter operates
at a fixed 2MHz switching frequency, enabling the use
of very small external components to achieve a com-
pact circuit area. For improved efficiency, the step-up
converter automatically transitions to pulse-skipping
mode at light loads.
Each of the five current regulators accommodates up to
9 series LEDs (depending on LED string forward volt-
age), and is independently programmed using an I2C
interface. Two of the current regulators (LED1, LED2)
are intended to support display backlight functions and
are programmable up to 25mA using a 128-step loga-
rithmic dimming scheme. The other three regulators
(LED3, LED4, LED5) are suitable for keyboard backlight
functions or for driving signal indicators, and are pro-
grammable up to 5mA using a 32-step logarithmic dim-
ming scheme. The low-current regulators (LED3, LED4,
LED5) can be operated from the step-up converter or
from a separate low-voltage source.
The I2C interface controls all operational aspects of the
current regulators, including: on/off state, LED current,
ramp-up/ramp-down timers, and blink rate timers
(LED3, LED4, LED5). The MAX8831 write/read address-
es are factory programmed at 0x9A/0x9B (contact the
factory for other address options).
The MAX8831 features open/short LED fault detection,
output overvoltage protection, thermal shutdown, and
open-circuit Schottky diode detection, with the status of
each fault monitored continually for readback through
the I2C interface.
The MAX8831 is available in a tiny 2mm x 2mm, 16-bump
WLP package.
Applications
Cell Phones
PDAs
Smartphones
Features
♦ 28V Step-Up DC-DC Converter
Integrated NMOS Power Switch
> 90% Efficiency
Fixed 2MHz Switching
Pulse Skipping for Improved Light-Load
Efficiency
Tiny External Components
♦ I2C Programmable (0x9A Write/0x9B Read),
Compatible with 1.8V Logic
♦ Two 25mA Regulators for Display Backlighting
I2C-Programmable Output Current (50µA to
25.25mA)
128-Step Logarithmic Dimming
Individually Programmable Ramp (Up/Down)
Timers
Low Dropout (200mV max)
♦ Three 5mA Current Regulators for Keypad
Lighting
I2C-Programmable Output Current (50µA to
5.0mA)
32-Step Logarithmic Dimming
Individually Programmable Ramp (Up/Down)
Timers
Individual Blink Rate and Duty Cycle Timers
Low Dropout (150mV max)
♦ Open/Short LED and Open-Circuit Diode
Detection
♦ Thermal-Shutdown and Output Overvoltage
Protection
♦ Ultra-Low 0.1mA Shutdown Current
♦ Tiny 2mm x 2mm, 16-Bump WLP Package
Ordering Information
PART
TEMP RANGE
PIN-PACKAGE
MAX8831EWE+T -40°C to +85°C
16 WLP
2mm x 2mm
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim's website at www.maxim-ic.com.
1 page  
www.DataSheet4U.com
High-Efficiency, White LED Step-Up Converter
with I2C Interface in 2mm x 2mm WLP
Typical Operating Characteristics
(VIN = 3.6V, VDD = 1.8V, CIN = 1µF, COUT = 1µF, CVDD = 0.1µF, CCOMP = 0.22µF, L = TOKO 1098AS-100M, ILED1 = ILED2 = 25.25mA,
ILED3 = ILED4 = ILED5 = 5mA, unless otherwise noted.)
CONVERTER EFFICIENCY
vs. INPUT VOLTAGE (LED1 STRING)
100
CONVERTER EFFICIENCY
vs. INPUT VOLTAGE (LED1 AND LED2 STRINGS)
100
CONVERTER EFFICIENCY
vs. INPUT VOLTAGE (LED3 STRING)
85
95
90
85
80 4 LEDs: VOUT = 13.35V
5 LEDs: VOUT = 16.63V
75
6 LEDs: VOUT = 19.83V
7 LEDs: VOUT = 23.07V
8 LEDs: VOUT = 26.23V
70
2.5 3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE (V)
95
90
85
80
75 4 LEDs: VOUT = 13.37V
70
5 LEDs: VOUT = 16.61V
6 LEDs: VOUT = 19.78V
65
7 LEDs: VOUT = 23.02V
8 LEDs: VOUT = 26.17V
60
2.5 3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE (V)
80
75
70
65
60
5 LEDs: VOUT = 15.04V
6 LEDs: VOUT = 17.97V
7 LEDs: VOUT = 20.97V
55 8 LEDs: VOUT = 23.97V
9 LEDs: VOUT = 26.81V
50
2.5 3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE (V)
CONVERTER EFFICIENCY
vs. INPUT VOLTAGE (LED3-TO-LED5 STRINGS)
90
88
86
84
82
80
78
76 5 LEDs: VOUT = 15.21V
6 LEDs: VOUT = 18.11V
74 7 LEDs: VOUT = 21.02V
72 8 LEDs: VOUT = 24.01V
9 LEDs: VOUT = 26.93V
70
2.5 3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE (V)
CONVERTER EFFICIENCY
vs. INPUT VOLTAGE (LED1–LED5 STRINGS)
100
LED1, LED2: 7 LEDs
95 LED3 TO LED5: 8 LEDs
VOUT = 23.86V
90
85
LED1, LED2: 8 LEDs
80 LED3 TO LED5: 8 LEDs
VOUT = 26.81V
75
70
65
2.5 3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE (V)
CONVERTER EFFICIENCY
vs. LED CURRENT (LED1 STRING)
90
4 LEDs
6 LEDs
80 8 LEDs
70
60
50
40
30
0
5 10 15 20
LED CURRENT (mA)
25
CONVERTER EFFICIENCY
vs. LED CURRENT (LED1 AND LED2 STRINGS)
90
3 LEDs
5 LEDs
80 8 LEDs
70
60
50
40
30
0
5 10 15 20
LED CURRENT (mA)
25
LED1, LED2 CURRENT ACCURACY
vs. LED CURRENT
10
8
6
ILED1 (ILED2 = 25.25mA)
4
2
0
-2
-4 ILED2 (ILED1 = 25.25mA)
-6
LED1, LED2: 8 LEDs
-8 LED3 TO LED5: 9 LEDs AT 5mA
-10
0
5 10 15
LED CURRENT (mA)
20
25
LED3-TO-LED5 CURRENT ACCURACY
vs. LED CURRENT
10
8 ILED5 (ILED4 = ILED3 = 5mA)
6 ILED4 (ILED5 = ILED3 = 5mA)
4
2
0
-2 ILED3 (ILED5 = ILED4 = 5mA)
-4
-6
-8
LED1, LED2: 8 LEDs AT 25.25mA
LED3 TO LED5: 9 LEDs
-10
0123
LED CURRENT (mA)
4
5
_______________________________________________________________________________________ 5
5 Page 
www.DataSheet4U.com
High-Efficiency, White LED Step-Up Converter
with I2C Interface in 2mm x 2mm WLP
Table 1. LED1, LED2 Programmable Current Levels and Register Values
ILED_CNTRL
REGISTER VALUE
0x00
0x01
0x02
0x03
0x04
0x05
0x06
0x07
0x08
0x09
0x0A
0x0B
0x0C
0x0D
0x0E
0x0F
0x10
0x11
0x12
0x13
0x14
0x15
0x16
0x17
0x18
0x19
0x1A
0x1B
0x1C
0x1D
0x1E
0x1F
0x20
0x21
0x22
0x23
0x24
0x25
ILED_ (mA)
0.05
0.1
0.2
0.25
0.35
0.45
0.55
0.65
0.75
0.85
1
1.1
1.2
1.35
1.45
1.6
1.75
1.85
2
2.15
2.3
2.45
2.6
2.75
2.9
3.05
3.2
3.35
3.5
3.65
3.85
4
4.15
4.35
4.55
4.7
4.9
5.05
ILED_CNTRL
REGISTER VALUE
0x2B
0x2C
0x2D
0x2E
0x2F
0x30
0x31
0x32
0x33
0x34
0x35
0x36
0x37
0x38
0x39
0x3A
0x3B
0x3C
0x3D
0x3E
0x3F
0x40
0x41
0x42
0x43
0x44
0x45
0x46
0x47
0x48
0x49
0x4A
0x4B
0x4C
0x4D
0x4E
0x4F
0x50
ILED_ (mA)
6.15
6.35
6.5
6.7
6.9
7.1
7.3
7.45
7.65
7.85
8.05
8.25
8.45
8.65
8.85
9.05
9.25
9.45
9.65
9.9
10.1
10.3
10.5
10.7
10.9
11.15
11.35
11.55
11.8
12
12.2
12.45
12.65
12.85
13.1
13.3
13.55
13.75
ILED_CNTRL
REGISTER VALUE
0x56
0x57
0x58
0x59
0x5A
0x5B
0x5C
0x5D
0x5E
0x5F
0x60
0x61
0x62
0x63
0x64
0x65
0x66
0x67
0x68
0x69
0x6A
0x6B
0x6C
0x6D
0x6E
0x6F
0x70
0x71
0x72
0x73
0x74
0x75
0x76
0x77
0x78
0x79
0x7A
0x7B
ILED_ (mA)
15.15
15.35
15.6
15.8
16.05
16.3
16.5
16.75
17
17.25
17.45
17.7
17.95
18.2
18.45
18.65
18.9
19.15
19.4
19.65
19.9
20.15
20.4
20.65
20.9
21.15
21.4
21.65
21.9
22.15
22.4
22.65
22.9
23.15
23.4
23.7
23.95
24.2
______________________________________________________________________________________ 11
11 Page | ||
| Páginas | Total 27 Páginas | |
| PDF Descargar | [ Datasheet MAX8831.PDF ] | |
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