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PDF MAX6947 Data sheet ( Hoja de datos )
| Número de pieza | MAX6947 | |
| Descripción | Constant-Current LED Drivers and I/O Expanders | |
| Fabricantes | Maxim Integrated Products | |
| Logotipo |  |
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19-0598; Rev 0; 7/06
10-Port, Constant-Current LED Drivers and
I/O Expanders with PWM Intensity Control
General Description
The MAX6946/MAX6947 I2C*-/SMBusTM-compatible,
serial-interfaced peripherals provide microprocessors
with 10 I/O ports rated to 7V.
Each port can be configured as a 2.5mA to 20mA con-
stant-current LED driver (static or PWM), a 1.25mA to
10mA constant-current LED driver (static or PWM), an
open-drain logic output, or an overvoltage-protected
Schmitt logic input.
Analog and switching LED intensity control includes indi-
www.DviadtuaaSlhe8e-bt4itUP.cWomM control per output, individual 1-bit ana-
log current control (half/full scale) per output, and a global
3-bit DAC current control that applies to all LED outputs.
The MAX6946/MAX6947 can stagger the PWM timing of
the 10-port outputs in consecutively phased 45° incre-
ments. Staggering the outputs spreads the PWM load
currents over time in eight steps, helping to even out
the power-supply current and reduce the RMS current.
For a similar part with a SPITM-/QSPITM-/ or MICROWIRETM-
compatible interface, refer to the MAX6966/MAX6967
data sheet.
Applications
Cellular Phones
Portable Equipment
RGB LED Drivers
LCD Backlights
Keypad Backlights
LED Status Indicators
Typical Operating Circuit
µC
SCL
SDA
*MAX6946 ONLY.
**MAX6947 ONLY.
+3.3V
VDD
SCL
SDA MAX6946
OSC* MAX6947
RST
AD0**
GND
P0
P1
P2
P3
P4
P5
P6
P7
P8
P9
+5V
LOGIC INPUT
LOGIC INPUT
LOGIC INPUT
LOGIC INPUT
LOGIC INPUT
LOGIC INPUT
LOGIC INPUT
*Purchase of I2C components from Maxim Integrated Products,
Inc., or one of its sublicensed Associated Companies, conveys
a license under the Philips I2C Patent Rights to use these com-
ponents in an I2C system, provided that the system conforms
to the I2C Standard Specification as defined by Philips.
SPI and QSPI are trademarks of Motorola, Inc.
MICROWIRE is a trademark of National Semiconductor Corp.
SMBus is a trademark of Intel Corp.
Features
♦ 400kb, 6V-Tolerant I2C-/SMBus-Compatible Serial
Interface
♦ 2.25V to 3.6V Operation
♦ I/O Ports Default to High Impedance (LEDs Off)
on Power-Up
♦ I/O Port Inputs Are Overvoltage Protected to 7V
♦ I/O Port Outputs Are 7V-Rated Open-Drain, 10mA
or 20mA Constant-Current Static/PWM LED
Drivers, or Open-Drain Logic Outputs
♦ I/O Ports Support Hot Insertion
♦ Individual 8-Bit PWM Intensity Control for Each LED
♦ RST Input Clears Serial Interface and Can Exit
Shutdown (Warm Start)
♦ MAX6946 OSC Input Allows for External PWM
Clock Input
♦ MAX6947 AD0 Input Selects from Four Slave
Addresses
♦ Auto Ramp-Up Out of Shutdown and Up to 4s
Hold-Off Before Ramp-Down into Shutdown
♦ 0.8µA (typ) Shutdown Current
♦ -40°C to +125°C Temperature Range
Ordering Information
PART
PIN-PACKAGE
TOP
MARK
PKG
CODE
MAX6946ATE+ 16 TQFN-EP**
MAX6947ATE+† 16 TQFN-EP**
ACF
ACG
T1633-4
T1633-4
Note: All devices are specified over the -40°C to +125°C operating
temperature range.
**EP = Exposed paddle.
+Denotes lead-free package.
†Future product—contact factory for availability.
Pin Configuration
TOP VIEW
12 11 10 9
RST 13
8 P6
VDD 14
SCL 15
MAX6946
MAX6947
7 P5
6 GND
SDA 16 +
5 P4
1234
TQFN (3mm x 3mm)
________________________________________________________________ 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  
10-Port, Constant-Current LED Drivers and
I/O Expanders with PWM Intensity Control
(TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics
STANDBY CURRENT (IRST)
vs. TEMPERATURE
2.0
1.6
1.2
www.DataSheet4U.com
0.8
VDD = 3.6V
VDD = 3.3V
VDD = 2.7V
SUPPLY CURRENT (IDD)
vs. TEMPERATURE
25
VDD = 3.6V VDD = 3.3V
20
15 VDD = 2.7V
10
STANDBY CURRENT (ISTBY)
vs. TEMPERATURE
25
VDD = 3.6V
20 VDD = 3.3V
15
10
0.4
VDD = 2.25V
0
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
5
VDD = 2.25V
0
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
5 VDD = 2.7V
VDD = 2.25V
0
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
DELTA SUPPLY CURRENT (IDD20)
vs. TEMPERATURE
4.0
3.6
VDD = 3.6V
VDD = 3.3V
3.2
DELTA SUPPLY CURRENT (IDD20)
vs. TEMPERATURE
15
VDD = 3.6V
12 VDD = 3.3V
9
OUTPUT SINKING CURRENT
vs. VEXT - VLED AT 10mA
14
12
10
8
2.8
2.4
VDD = 2.25V
VDD = 2.7V
2.0
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
6
3 VDD = 2.7V
VDD = 2.25V
0
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
6
4
2
0
01234
VEXT - VLED (V)
OUTPUT SINKING CURRENT
vs. VEXT - VLED AT 20mA
24
STAGGER PWM PORT WAVEFORMS
(OUTPUT REGISTERS SET TO 0x80)
MAX6946/47 toc08
5
20
PORT P0
16 2V/div
12 PORT P4
2V/div
8
PORT P7
4 2V/div
0
012345
VEXT - VLED (V)
1ms/div
_______________________________________________________________________________________ 5
5 Page 
10-Port, Constant-Current LED Drivers and
I/O Expanders with PWM Intensity Control
PWM Intensity Control and Phasing
The MAX6946/MAX6947 use an internal 32kHz oscilla-
tor to generate PWM timing for LED intensity control.
The MAX6946 also features an OSC input to allow for
an external clock for generating PWM timing for LED
intensity control. Select the PWM clock source for the
MAX6946 with configuration register bit D7 (Table 2).
The MAX6947 powers up configured to use the internal
32kHz oscillator by default. The MAX6946 powers up
configured to use the external clock source by default.
A PWM period comprises 256 cycles of the nominal
www.D3a2tkaHShzePeWt4UM.ccolmock (Figure 2). Individually set the ports’
PWM duty cycle between 3/256 and 254/256. See
Table 4 for port register settings.
Configure PWM timing by setting the stagger bit in the
configuration register (Table 2), either with output stag-
gering or without. Clearing the stagger bit causes all
outputs using PWM to switch at the same time using
the timing shown in Figure 2. All outputs, therefore,
draw load current at the exactly same time for the same
PWM setting. This means that if, for example, all out-
puts are set to 0x80 (128/256 duty cycle), the current
draw would be zero (all loads off) for half the time, and
full (all loads on) for the other half.
Setting the stagger bit causes the PWM timing of the 10
port outputs to stagger by 32 counts of the 256-count
PWM period (i.e., 1/8th), distributing the port output
switching points across the PWM period (Figure 3).
Staggering reduces the di/dt output-switching transient
on the supply and also reduces the peak/mean current
requirement.
Set or clear the stagger bit during shutdown. Changing
the stagger bit during normal operation can cause a
transient flicker in any PWM-controlled LEDs because
of the fundamental PWM timing changes.
OUTPUT
REGISTER
VALUE
0x00
0x01
0x02
0x03
0x04
0xFC
0xFD
0xFE
0xFF
7.8125ms NOMINAL PWM PERIOD
OUTPUT STATIC-LOW LOGIC DRIVE WITH INPUT BUFFER ENABLED (GPI)
OUTPUT STATIC-HIGH LOGIC DRIVE WITH INPUT BUFFER ENABLED (GPI)
OUTPUT STATIC-LOW CONSTANT CURRENT WITH INPUT BUFFER DISABLED (STATIC LED DRIVE ON)
OUTPUT LOW 3/256 DUTY CONSTANT CURRENT WITH INPUT BUFFER DISABLED (PWM LED DRIVE)
OUTPUT LOW 4/256 DUTY CONSTANT CURRENT WITH INPUT BUFFER DISABLED (PWM LED DRIVE)
OUTPUT LOW 252/256 DUTY CONSTANT CURRENT WITH INPUT BUFFER DISABLED (PWM LED DRIVE)
OUTPUT LOW 253/256 DUTY CONSTANT CURRENT WITH INPUT BUFFER DISABLED (PWM LED DRIVE)
OUTPUT LOW 254/256 DUTY CONSTANT CURRENT WITH INPUT BUFFER DISABLED (PWM LED DRIVE)
OUTPUT STATIC HIGH IMPEDANCE WITH INPUT BUFFER DISABLED (STATIC LED DRIVE OFF)
Figure 2. Static and PWM Constant-Current Waveforms
HIGH-Z
LOW
HIGH-Z
LOW
HIGH-Z
LOW
HIGH-Z
LOW
HIGH-Z
LOW
HIGH-Z
LOW
HIGH-Z
LOW
HIGH-Z
LOW
HIGH-Z
LOW
______________________________________________________________________________________________________ 11
11 Page | ||
| Páginas | Total 22 Páginas | |
| PDF Descargar | [ Datasheet MAX6947.PDF ] | |
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