MAX6957AAX ,4-Wire-Interfaced, 2.5V to 5.5V, 20-Port and 28-Port LED Display Driver and I/O ExpanderApplicationsMAX6957AGL* -40°C to +125°C 40 QFNSet-Top Boxes*Future product—contact factory for avai ..
MAX6957AAX+ ,4-Wire-Interfaced, 2.5V to 5.5V, 20-Port and 28-Port LED Display Driver and I/O ExpanderMAX6957 4-Wire-Interfaced, 2.5V to 5.5V, 20-Port and 28-Port LED Display Driver and I/O Expander
MAX6957ANI+ ,4-Wire-Interfaced, 2.5V to 5.5V, 20-Port and 28-Port LED Display Driver and I/O ExpanderElectrical Characteristics(Typical Operating Circuit, V+ = 2.5V to 5.5V, T = T to T , unless otherw ..
MAX6957ATL ,4-Wire-Interfaced, 2.5V to 5.5V, 20-Port and 28-Port LED Display Driver and I/O ExpanderApplicationsGND 2 27 CS● Set-Top BoxesDINGND 3 26● Panel MetersSCLKDOUT 4 25● White GoodsP12 5 24 P ..
MAX6957ATL ,4-Wire-Interfaced, 2.5V to 5.5V, 20-Port and 28-Port LED Display Driver and I/O ExpanderApplicationsGND 2 27 CS● Set-Top BoxesDINGND 3 26● Panel MetersSCLKDOUT 4 25● White GoodsP12 5 24 P ..
MAX6957ATL+ ,4-Wire-Interfaced, 2.5V to 5.5V, 20-Port and 28-Port LED Display Driver and I/O ExpanderFeatures®The MAX6957 compact, serial-interfaced LED display ● High-Speed 26MHz SPI-/QSPI™-/MICROWI ..
MB401 , 40 Amp Single Phase Bridge Rectifier 50 to 1000 Volts
MB401 , 40 Amp Single Phase Bridge Rectifier 50 to 1000 Volts
MB401 , 40 Amp Single Phase Bridge Rectifier 50 to 1000 Volts
MB40166 ,AD/DA CONVERTERFUJITSU SEMICONDUCTORDS04-28500-5EDATA SHEETASSPAD/DA CONVERTERMB40166/MB401761-CHANNEL 6-BIT AD/DA ..
MB40176 ,AD/DA CONVERTERFUJITSU SEMICONDUCTORDS04-28500-5EDATA SHEETASSPAD/DA CONVERTERMB40166/MB401761-CHANNEL 6-BIT AD/DA ..
MB40176 ,AD/DA CONVERTERFUJITSU SEMICONDUCTORDS04-28500-5EDATA SHEETASSPAD/DA CONVERTERMB40166/MB401761-CHANNEL 6-BIT AD/DA ..
MAX6957AAX
4-Wire-Interfaced, 2.5V to 5.5V, 20-Port and 28-Port LED Display Driver and I/O Expander
General DescriptionThe MAX6957 compact, serial-interfaced LED display
driver general-purpose I/O (GPIO) peripheral provides
microprocessors with up to 28 ports. Each port is indi-
vidually user configurable to either a logic input, logic
output, or common-anode (CA) LED constant-current
segment driver. Each port configured as an LED seg-
ment driver behaves as a digitally controlled constant-
current sink, with 16 equal current steps from 1.5mA to
24mA. The LED drivers are suitable for both discrete
LEDs and CA numeric and alphanumeric LED digits.
Each port configured as a GPIO can be either a push-
pull logic output capable of sinking 10mA and sourcing
4.5mA, or a Schmitt logic input with optional internal
pullup. Seven ports feature configurable transition
detection logic, which generates an interrupt upon
change of port logic level. The MAX6957 is controlled
through an SPI™-compatible 4-wire serial interface.
The MAX6957AAX and MAX6957AGL have 28 ports and
are available in 36-pin SSOP and 40-pin QFN packages,
respectively. The MAX6957AAI and MAX6957ANI have
20 ports and are available in 28-pin SSOP and 28-pin DIP
packages, respectively.
ApplicationsSet-Top Boxes
Panel Meters
White Goods
Automotive
Bar Graph Displays
Industrial Controllers
System Monitoring
FeaturesHigh-Speed 26MHz SPI-/QSPI-™/MICROWIRE™-
Compatible Serial Interface2.5V to 5.5V Operation-40°C to +125°C Temperature Range20 or 28 I/O Ports, Each Configurable as
Constant-Current LED Driver
Push-Pull Logic Output
Schmitt Logic Input
Schmitt Logic Input with Internal Pullup11µA (max) Shutdown Current16-Step Individually Programmable Current
Control for Each LEDLogic Transition Detection for Seven I/O Ports
MAX6957
4-Wire-Interfaced, 2.5V to 5.5V, 20-Port and
28-Port LED Display Driver and I/O Expander
Pin Configurations19-2429; Rev 0; 4/02
Typical Operating Circuit appears at end of data sheet.
Ordering InformationSPI and QSPI are trademarks of Motorola, Inc.
MICROWIRE is a trademark of National Semiconductor Corp.
*Future product—contact factory for availability.
MAX6957
4-Wire-Interfaced, 2.5V to 5.5V, 20-Port and
28-Port LED Display Driver and I/O Expander
ABSOLUTE MAXIMUM RATINGSStresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
Voltage (with Respect to GND) .............................................................................-0.3V to +6V
All Other pins................................................-0.3V to (V+ + 0.3V)
P4–P31 Current ................................................................±30mA
GND Current.....................................................................800mA
Continuous Power Dissipation (TA= +70°C)
28-Pin PDIP (derate 20.8mW/°C above +70°C)........1667mW
28-Pin SSOP (derate 9.5mW/°C above +70°C)..........762mW
36-Pin SSOP (derate 11.8mW/°C above +70°C)........941mW
Operating Temperature Range (TMIN, TMAX)....-40°C to +125°C
Junction Temperature......................................................+150°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s).................................+300°C
ELECTRICAL CHARACTERISTICS(Typical Operating Circuit, V+ = 2.5V to 5.5V, TA= TMINto TMAX, unless otherwise noted.) (Note 1)
MAX6957
4-Wire-Interfaced, 2.5V to 5.5V, 20-Port and
28-Port LED Display Driver and I/O Expander
Note 1:All parameters tested at TA= +25°C. Specifications over temperature are guaranteed by design.
Note 2:Guaranteed by design.
ELECTRICAL CHARACTERISTICS (continued)
TIMING CHARACTERISTICS (Figure 3)
MAX6957
4-Wire-Interfaced, 2.5V to 5.5V, 20-Port and
28-Port LED Display Driver and I/O Expander
__________________________________________Typical Operating Characteristics(RISET= 39kΩ, TA = +25°C, unless otherwise noted.)
Detailed DescriptionThe MAX6957 LED driver/GPIO peripheral provides up
to 28 I/O ports, P4 to P31, controlled through an SPI-
compatible serial interface. The ports can be config-
ured to any combination of constant-current LED
drivers, logic inputs and logic outputs, and default to
logic inputs on power-up. When fully configured as an
LED driver, the MAX6957 controls up to 28 LED seg-
ments with individual 16-step adjustment of the con-
stant current through each LED segment. A single
resistor sets the maximum segment current for all seg-
ments, with a maximum of 24mA per segment. The
MAX6957 drives any combination of discrete LEDs and
CA digits, including seven-segment and starburst
alphanumeric types.
Figure 1 is the MAX6957 functional diagram. Any I/O
port can be configured as a push-pull output (sinking
10mA, sourcing 4.5mA), or a Schmitt-trigger logic
input. Each input has an individually selectable internal
pullup resistor. Additionally, transition detection allows
seven ports (P24 through P30) to be monitored in any
maskable combination for changes in their logic status.
A detected transition is flagged through a status regis-
ter bit, as well as an interrupt pin (port P31), if desired.
The Typical Operating Circuitshows two MAX6957s
working together controlling three monocolor 16-seg-
ment-plus-DP displays, with five ports left available for
GPIO (P27–P31 of U2).
The port configuration registers set the 28 ports, P4 to
P31, individually as either LED drivers or GPIO. A pair
of bits in registers 0x09 through 0x0F sets each port’s
configuration (Tables 1 and 2).
The 36-pin MAX6957AAX has 28 ports, P4 to P31. The
28-pin MAX6957ANI and MAX6957AAI only use 20 out-
puts, P12 to P31. The eight unused ports should be
configured as outputs on power-up by writing 0x55 to
registers 0x09 and 0x0A. If this is not done, the eight
unused ports remain as floating inputs and quiescent
supply current rises, although there is no damage to
the part.
Register Control of I/O Ports and LEDs
Across Multiple DriversThe MAX6957 offers 20 or 28 I/O ports, depending on
package choice. These can be applied to a variety of
combinations of different display types, for example:
seven, 7-segment digits (Figure 2). This example
requires two MAX6957s, with one digit being driven by
both devices, half by one MAX6957, half by the other
(digit 4 in this example). The two drivers are static, and
therefore do not need to be synchronized. The
MAX6957 sees CA digits as multiple discrete LEDs. To
simplify access to displays that overlap two MAX6957s,
the MAX6957 provides four virtual ports P0 through P3.
To update an overlapping digit, send the same code
twice as an eight-port write, once to P28 through P35 of
the first driver, and again to P0 through P7 of the sec-
MAX6957
4-Wire-Interfaced, 2.5V to 5.5V, 20-Port and
28-Port LED Display Driver and I/O Expander
Pin Description
MAX6957ond driver. The first driver ignores the last 4 bits and
the second driver ignores the first 4 bits.
Two addressing methods are available. Any single port
(bit) can be written (set/cleared) at once; or, any
sequence of eight ports can be written (set/cleared) in
any combination at once. There are no boundaries; it is
equally acceptable to write P0 through P7, P1 through
P8, or P31 through P38 (P32 through P38 are nonexis-
tent, so the instructions to these bits are ignored).
Using 8-bit control, a seven-segment digit with a deci-
mal point can be updated in a single byte-write, a 14-
segment digit with DP can be updated in two
byte-writes, and 16-segment digits with DP can be
updated in two byte-writes plus a bit write. Also, dis-
crete LEDs and GPIO port bits can be lit and controlled
individually without affecting other ports.
ShutdownWhen the MAX6957 is in shutdown mode, all ports are
forced to inputs, and the pullup current sources are
turned off. Data in the port and control registers remain
unaltered so port configuration and output levels are
restored when the MAX6957 is taken out of shutdown.
The display driver can still be programmed while in
shutdown mode. For minimum supply current in shut-
down mode, logic inputs should be at GND or V+
potential. Shutdown mode is exited by setting the S bit
in the configuration register (Table 6). Shutdown mode
is temporarily overridden by the display test function.
4-Wire-Interfaced, 2.5V to 5.5V, 20-Port and
28-Port LED Display Driver and I/O Expanderturn that segment on; in GPIO output mode (0x01), a high makes the output go high.
Serial InterfaceThe MAX6957 communicates through an SPI-compati-
ble 4-wire serial interface. The interface has three
inputs, Clock (SCLK), Chip Select (CS), and Data In
(DIN), and one output, Data Out (DOUT). CSmust be
low to clock data into or out of the device, and DIN
must be stable when sampled on the rising edge of
SCLK. DOUT provides a copy of the bit that was input
15.5 clocks earlier, or upon a query it outputs internal
register data, and is stable on the rising edge of SCLK.
Note that the SPI protocol expects DOUT to be high
impedance when the MAX6957 is not being accessed;
DOUT on the MAX6957 is never high impedance.
SCLK and DIN may be used to transmit data to other
peripherals, so the MAX6957 ignores all activity on
SCLK and DIN except between the fall and subsequent
rise of CS.
Control and Operation Using the
4-Wire InterfaceControlling the MAX6957 requires sending a 16-bit
word. The first byte, D15 through D8, is the command
address (Table 3), and the second byte, D7 through
D0, is the data byte (Table 4).
Connecting Multiple MAX6957s to the 4-Wire BusMultiple MAX6957s may be daisy-chained by connect-
ing the DOUT of one device to the DIN of the next, and
driving SCLK and CSlines in parallel (Figure 4). Data at
DIN propagates through the internal shift registers and
appears at DOUT 15.5 clock cycles later, clocked out
on the falling edge of SCLK. When sending commands
MAX6957
4-Wire-Interfaced, 2.5V to 5.5V, 20-Port and
28-Port LED Display Driver and I/O ExpanderFigure 1. MAX6957 Functional Diagram
MAX6957
4-Wire-Interfaced, 2.5V to 5.5V, 20-Port and
28-Port LED Display Driver and I/O Expander
to multiple MAX6957s, all devices are accessed at the
same time. An access requires (16 ✕n) clock cycles,
where n is the number of MAX6957s connected togeth-
er. To update just one device in a daisy-chain, the user
can send the No-Op command (0x00) to the others.
Writing Device Registers The MAX6957 contains a 16-bit shift register into which
DIN data are clocked on the rising edge of SCLK, whenis low. When CSis high, transitions on SCLK have
no effect. When CSgoes high, the 16 bits in the Shift
register are parallel loaded into a 16-bit latch. The 16
bits in the latch are then decoded and executed.
The MAX6957 is written to using the following
sequence: Take SCLK low.Take CSlow. This enables the internal 16-bit shift
register. Clock 16 bits of data into DIN—D15 first, D0 last—
observing the setup and hold times (bit D15 is low,
indicating a write command). Take CShigh (while SCLK is still high after clocking
in the last data bit). Take SCLK low.
Figure 5 shows a write operation when 16 bits are
transmitted.
It is acceptable to clock more than 16 bits into the
MAX6957 between taking CSlow and taking CShigh
again. In this case, only the last 16 bits clocked into the
MAX6957 are retained.
Reading Device RegistersAny register data within the MAX6957 may be read by
sending a logic high to bit D15. The sequence is: Take SCLK low.Take CSlow (this enables the internal 16-bit shift
register).Clock 16 bits of data into DIN—D15 first to D0 last.
D15 is high, indicating a read command and bits
D14 through D8 containing the address of the reg-
ister to be read. Bits D7–D0 contain dummy data,
which is discarded.
MAX6957
4-Wire-Interfaced, 2.5V to 5.5V, 20-Port and
28-Port LED Display Driver and I/O ExpanderFigure 5.16-Bit Write Transmission to the MAX6957
MAX6957Take CShigh (while SCLK is still high after clocking
in the last data bit), positions D7 through D0 in the
Shift register are now loaded with the register data
addressed by bits D1 through D8. Take SCLK low. Issue another read or write command (which can
be a No-Op), and examine the bit stream at DOUT;
the second 8 bits are the contents of the register
addressed by bits D1 through D8 in step 3.
Initial Power-UpOn initial power-up, all control registers are reset, cur-
rent registers are set to minimum value, and the
MAX6957 enters shutdown mode (Table 4).
LED Current ControlLED segment drive current can be set either globally or
individually. Global control simplifies the operation
when all LEDs are set to the same current level,
because writing one register, the Global Current regis-
ter, sets the current for all ports configured as LED seg-
ment drivers. It is also possible to individually control
the current drive of each LED segment driver.
Individual/global brightness control is selected by set-
ting the configuration register I bit (Table7). The global
current register (0x02) data are then ignored, and seg-
ment currents are set using register addresses 0x12
through 0x1F (Tables 10, 11, and 12). Each segment is
controlled by a nibble of one of the 16 current registers.
Transition (Port Data Change) DetectionPort transition detection allows seven maskable ports
P24 through P30 to be continuously monitored for
changes in their logic status (Figure 6). Enable transi-
tion detection by setting the M bit in the configuration
register (Table 8) after setting the mask register. If port
31 is configured as an output (Tables 1 and 2), then
P31 automatically becomes an interrupt request (IRQ)
output to flag detected transitions. Port 31 can be con-
figured and used as a general-purpose input port
instead if not required as the IRQ output.
The mask register determines which of the seven ports
P24 through P30 are monitored (Table 13). Set the
appropriate mask bit to enable that port for transition
detect. Clear the mask bit if transitions on that port are
to be ignored by the transition detection logic. Ports are
monitored regardless of their I/O configuration, both
input and output.
The MAX6957 maintains an internal 7-bit snapshot reg-
ister to hold the comparison copy of the logic states of
ports P24 through P30. The snapshot register is updat-
ed with the condition of P24 through P31 whenever the
configuration register is written with the M bit set. The
update action occurs regardless of the previous state
of the M bit so that it is not necessary to clear the M bit
and then set it again to update the snapshot register.
When the data change detection bit is set, the
MAX6957 continuously compares the snapshot register
against the changing states of P24 through P31. When
a difference occurs, the IRQ bit (mask register bit D7) is
set and IRQ port P31 goes high if it is configured as an
output.
The IRQ bit and IRQ output remain set until the mask
register is next read or written, so if the IRQ is set, then
the mask register reads with bit D7 set. Writing the
mask register clears the IRQ output and resets the IRQ
bit, regardless of the value of bit D7 written.
Display Test RegisterDisplay test mode turns on all ports configured as LED
drivers by overriding, but not altering, all controls and
port registers, except the port configuration register
(Table 14). Only ports configured as LED drivers are
affected. Ports configured as GPIO push-pull outputs
do not change state. In display test mode, each port's
current is temporarily set to 1/2 the maximum current
limit as controlled by RISET.
Selecting External Component RISET
to Set Maximum Segment CurrentThe MAX6957 uses an external resistor RISETto set the
maximum segment current. The recommended value,
39kΩ, sets the maximum current to 24mA, which makes
the segment current adjustable from 1.5mA to 24mA in
1.5mA steps.
To set a different segment current, use the formula:
RISET= 936kΩ/ ISEG
where ISEGis the desired maximum segment current in mA.
The recommended value of RISETis 39kΩ.
The recommended value of RISETis the minimum
allowed value, since it sets the display driver to the
maximum allowed segment current. RISETcan be a
higher value to set the segment current to a lower maxi-
mum value where desired. The user must also ensure
that the maximum current specifications of the LEDs
connected to the driver are not exceeded.
The drive current for each segment can be controlled
through programming either the global current register
(Table 9) or individual segment current registers
(Tables 10, 11, and 12), according to the setting of the
current control bit of the configuration register (Table 7).
4-Wire-Interfaced, 2.5V to 5.5V, 20-Port and
28-Port LED Display Driver and I/O Expander
MAX6957
4-Wire-Interfaced, 2.5V to 5.5V, 20-Port and
28-Port LED Display Driver and I/O Expander
MAX6957
4-Wire-Interfaced, 2.5V to 5.5V, 20-Port and
28-Port LED Display Driver and I/O Expander
