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PDF MAX8647 Data sheet ( Hoja de datos )
| Número de pieza | MAX8647 | |
| Descripción | (MAX8647 / MAX8648) Ultra-Efficient Charge Pumps | |
| Fabricantes | Maxim Integrated Products | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de MAX8647 (archivo pdf) en la parte inferior de esta página. Total 15 Páginas | ||
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19-0790; Rev 0; 4/07
EVAALVUAAILTAIOBNLEKIT
Ultra-Efficient Charge Pumps for
Six White/RGB LEDs in 3mm x 3mm Thin QFN
General Description
The MAX8647/MAX8648 drive up to six white LEDs or
two sets of RGB LEDs with regulated constant current
for display backlight and fun light applications. By utiliz-
ing an inverting charge pump and extremely low-
dropout adaptive current regulators, these ICs achieve
very high efficiency over the full 1-cell Li+ battery volt-
age range and even with large LED forward voltage
mismatch. The 1MHz fixed-frequency switching allows
for tiny external components. The regulation scheme is
optimized to ensure low EMI and low input ripple. The
MAX8647/MAX8648 include thermal shutdown, open-
and short-circuit protection.
The MAX8647 features an I2C serial port, while the
MAX8648 features a three-wire serial-pulse logic inter-
face. Both devices support independent on/off and
dimming for main and subbacklights. The dimming
ranges are pseudo-logarithmic from 24mA to 0.1mA
and off in 32 steps. Both devices include a temperature
derating function to safely allow bright 24mA full-scale
output current setting while automatically reducing cur-
rent to protect LEDs at high ambient temperatures
above +60°C.
The MAX8647/MAX8648 are available in a 16-pin, 3mm
x 3mm thin QFN package (0.8mm max height).
Applications
White LED Backlighting, Single or Dual Display
Wide-Gamut RGB LED Display Backlighting
www.DataSheetC4Uam.coemra Flash or RGB Indicators
Cellular Phones and Smartphones
PDAs, Digital Cameras, and Camcorders
Pin Configuration
TOP VIEW
12 11 10 9
LED1 13
SDA (ENC) 14
SCL (ENB) 15
MAX8647ETE
MAX8648ETE
VDD (ENA) 16 +
1234
8 LED6
7 NEG
6 C1N
5 C2N
THIN QFN
( ) DESIGNATE PINS ON THE MAX8648
Features
♦ Six Adaptive Current Regulators
♦ Independent Voltage Supply for Each LED
♦ Individual LED Brightness Control (MAX8647)
♦ 24mA to 0.1mA Dimming Range
I2C Interface (MAX8647)
Serial-Pulse Dimming Logic (MAX8648)
♦ ±2% Accuracy, ±0.4% Matching (typ)
♦ Low 70µA Quiescent Current
♦ Low 1µA Shutdown Current
♦ Inrush Current Limit
♦ TA Derating Function Protects LEDs
♦ 16-Pin, 3mm x 3mm Thin QFN Package
Ordering Information
PART
DIMMING
PIN
PACKAGE
TOP PKG
MARK CODE
MAX8647ETE+ I2C interface 16 Thin QFN-EP* AFD T1633-5
MAX8648ETE+
Serial-pulse
logic
16 Thin QFN-EP*
AFE
T1633-5
Note: All devices are specified over the -40°C to +85°C extended
temperature range.
+Denotes a lead-free package.
*EP = Exposed paddle.
Typical Operating Circuit
INPUT
2.7V TO 5.5V
1μF
SERIAL-
PULSE
INTERFACE
1μF 1μF
C1P
IN
GND
C1N C2P
C2N
NEG
EP
MAX8648
LED1
LED2
ENA LED3
ENB LED4
ENC LED5
LED6
1μF
WHITE
OR RGB LED
D1
D2
D3
D4
D5
D6
________________________________________________________________ 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  
Ultra-Efficient Charge Pumps for
Six White/RGB LEDs in 3mm x 3mm Thin QFN
Typical Operating Characteristics (continued)
(VIN = 3.6V, VEN_ = VIN, circuit of Figure 1, TA = +25°C, unless otherwise noted.)
EFFICIENCY vs. SUPPLY VOLTAGE
(DRIVING SIX LEDs)
100
90
80
70
60 20.8mA/LED
50 6.4mA/LED
40
30
20
10
LEDs HAVE MISMATCHED VF
0
2.7 3.0 3.3 3.6
INPUT VOLTAGE (V)
3.9
4.2
INPUT CURRENT vs. INPUT VOLTAGE
(DRIVING SIX LEDs)
200
180 ILED = 20.8mA
160
140
120
100 ILED = 16mA
80 LEDs HAVE MISMATCHED VF
60
www.DataSh40eet4U.com
ILED = 6.4mA
20
0
2.7
ILED = 1.6mA
3.2 3.7
INPUT VOLTAGE (V)
4.2
INPUT CURRENT vs. Li+ BATTERY
VOLTAGE (RGB MODULE)
100
RGB MODULE: LUMEX SML-LX3632SISUGSBC
90
80 20.8mA/LED
70
16mA/LED
60
50
40
30 6.4mA/LED
20
10 1.6mA/LED
0
4.2 3.9 3.8 3.7 3.6 3.5 3.4 3.0
Li+ BATTERY VOLTAGE (V, TIME-WEIGHTED)
EFFICIENCY vs. Li+ BATTERY VOLTAGE
(DRIVING SIX LEDs)
100
16mA/LED
90
80
70
1.6mA/LED
60
50
LEDs HAVE MISMATCHED VF
40
4.2 3.9 3.8 3.7 3.6
3.5 3.4 3.0
Li+ BATTERY VOLTAGE (V, TIME-WEIGHTED)
INPUT CURRENT vs. Li+ BATTERY
VOLTAGE (DRIVING SIX LEDs)
200
LEDs HAVE MISMATCHED VF
180
160
140 20.8mA/LED
120
16mA/LED
100
80
60
6.4mA/LED
40
20 1.6mA/LED
0
4.2 3.9
3.8 3.7
3.6 3.5 3.4 3.0
Li+ BATTERY VOLTAGE (V, TIME-WEIGHTED)
INPUT RIPPLE VOLTAGE vs. SUPPLY
VOLTAGE (DRIVING SIX WHITE LEDs)
16
20.8mA/LED
14
12 16mA/LED
10
8
6.4mA/LED
6
4
LEDs HAVE
MISMATCHED VF
2
1.6mA/LED
0
2.7 3.2
3.7
SUPPLY VOLTAGE (V)
4.2
EFFICIENCY vs. Li+ BATTERY VOLTAGE
(DRIVING SIX LEDs)
100
90
80
6.4mA/LED
70
60
20.8mA/LED
50
LEDs HAVE MISMATCHED VF
40
4.2 3.9 3.8 3.7 3.6
3.5 3.4 3.0
Li+ BATTERY VOLTAGE (V, TIME-WEIGHTED)
INPUT CURRENT
vs. INPUT VOLTAGE (RGB MODULE)
100
RGB MODULE: LUMEX SML-LX3632SISUGSBC
90
80 ILED = 20.8mA
70
60 ILED = 16mA
50
40
30 ILED = 4.8mA
20
10 ILED = 1.6mA
0
2.7 3.2 3.7 4.2
INPUT VOLTAGE (V)
LED CURRENT MATCHING
vs. INPUT VOLTAGE (16mA/LED)
17.0
16.8
16.6
16.4
16.2
16.0
15.8
15.6
15.4
15.2
15.0
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
INPUT VOLTAGE (V)
_______________________________________________________________________________________ 5
5 Page 
Ultra-Efficient Charge Pumps for
Six White/RGB LEDs in 3mm x 3mm Thin QFN
A tLOW B tHIGH C D E F
SCL
G
H IJ
K LM
SDA
tSU_STA tHD_STA
A = START CONDITION
B = MSB OF ADDRESS CLOCKED INTO SLAVE
C = LSB OF ADDRESS CLOCKED INTO SLAVE
D = R/W BIT CLOCKED INTO SLAVE
E = SLAVE PULLS SMBDATA LINE LOW
tSU_DAT
tHD_DAT
F = ACKNOWLEDGE BIT CLOCKED INTO MASTER
G = MSB OF DATA CLOCKED INTO SLAVE (OP/SUS BIT)
H = LSB OF DATA CLOCKED INTO SLAVE
I = SLAVE PULLS SMBDATA LINE LOW
Figure 2. Definition of Timing for I2C Bus
tSU_STO tBUF
J = ACKNOWLEDGE CLOCKED INTO MASTER
K = ACKNOWLEDGE CLOCK PULSE
L = STOP CONDITION, DATA EXECUTED BY SLAVE
M = NEW START CONDITION
Table 4. MAX8648 Pulse Dimming Step vs. LED Currents
mA
24.0
22.4
20.8
19.2
17.6
16.0
14.4
12.8
www.DataSheet41U1..c2om
9.6
8.0
6.4
5.6
4.8
4.0
3.2
MAX8648 DIMMING STEPS
Startup or EN_ high
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
mA
2.8
2.4
2.0
1.6
1.4
1.2
1.0
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
24.0
MAX8648 DIMMING STEPS
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
below the switch over threshold enabling the inverting
charge pump.
For the MAX8647, program any unused LED_ to off
using the I2C interface. Unused LED_ can be connect-
ed to IN or left unconnected.
Thermal Shutdown
The MAX8647/MAX8648 includes a thermal-limit circuit
that shuts down the IC above about +160°C. The IC
turns on after it cools by approximately 20°C.
Applications Information
Input Ripple
For LED drivers, input ripple is more important than out-
put ripple. The amount of input ripple depends on the
source supply’s output impedance. Adding a lowpass
filter to the input of the MAX8647/MAX8648 further
reduces input ripple. Alternatively, increasing CIN to
2.2µF (or 4.7µF) cuts input ripple in half (or in fourth)
with only a small increase in footprint.
______________________________________________________________________________________ 11
11 Page | ||
| Páginas | Total 15 Páginas | |
| PDF Descargar | [ Datasheet MAX8647.PDF ] | |
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