Rainbow Electronics MAX7315 User Manual

General Description

The MAX7315 I2C™-/SMBus-compatible serial interfaced peripheral provides microprocessors with 8 I/O ports. Each I/O port can be individually configured as either an open-drain current-sinking output rated at 50mA at 5.5V, or a logic input with transition detection. A ninth port can be used for transition detection interrupt or as a generalpurpose output. The outputs are capable of directly driving LEDs, or providing logic outputs with external resistive pullup up to 5.5V.

PWM current drive is integrated with 8 bits of control. Four bits are global control and apply to all LED outputs to provide coarse adjustment of current from fully off to fully on in 14 intensity steps. Each output then has individual 4-bit control, which further divides the globally set current into 16 more steps. Alternatively, the current control can be configured as a single 8-bit control that sets all outputs at once.

The MAX7315 is pin and software compatible with the PCA9534 and PCA9554(A).

Each output has independent blink timing with two blink phases. All LEDs can be individually set to be on or off during either blink phase, or to ignore the blink control. The blink period is controlled by a register.

The MAX7315 is controlled through the 2-wire I2C/SMBus serial interface, and can be configured to one of 64 I2C addresses.

Applications

Features

♦ 400kbps, 2-Wire Serial Interface, 5.5V Tolerant ♦ 2V to 3.6V Operation ♦ Overall 8-Bit PWM LED Intensity Control

Global 16-Step Intensity Control Plus Individual 16-Step Intensity Control

♦ Automatic Two-Phase LED Blinking ♦ 50mA Maximum Port Output Current ♦ Outputs Are 5.5V-Rated Open Drain ♦ Inputs Are Overvoltage Protected to 5.5V ♦ Transition Detection with Interrupt Output ♦ Low Standby Current (1.2µA typ; 3.3µA max) ♦ Tiny 3mm x 3mm, Thin QFN Package ♦ -40°C to +125°C Temperature Range ♦ All Ports Can Be Configured as Inputs or Outputs

MAX7315

8-Port I/O Expander with LED Intensity

Control and Interrupt

________________________________________________________________ Maxim Integrated Products 1

Pin Configurations

MAX7315

P0 P1 P2 P3

V+

3.3V

µC

SDA

SCL

SDA

I/O

AD0

5V 3.3V

P6 P7

SCL

OUTPUT2

OUTPUT1

GND

INPUT 1 INPUT 2

AD2

AD1

0.047µF

INT/O8

Typical Application Circuit

19-3056; Rev 0; 10/03

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.

Ordering Information

Pin Configurations continued at end of data sheet.

LCD Backlights

LED Status Indication

Portable Equipment

Laptop Computers

Keypad Backlights

RGB LED Drivers

Cellular Phones

Purchase of I2C components of Maxim Integrated Products, Inc., or one of its sublicensed Associated Companies, conveys a license under the Philips I

C Patent Rights to use these compo-

nents in an I

C system, provided that the system conforms to the

C Standard Specification as defined by Philips.

PART TEMP RANGE PIN-PACKAGE

MAX7315ATE -40°C to +125°C

MAX7315AEE -40°C to +125°C 16 QSOP —

MAX7315AUE -40°C to +125°C 16 TSSOP —

16 Thin QFN 3mm x 3mm x

0.8mm

TOP

MARK

AAU

TOP VIEW

AD2

AD0

V+

GND

SDA

SCL

INT/O8

AD1

16 15 14 13

MAX7315ATE

5678

QFN

MAX7315

8-Port I/O Expander with LED Intensity Control and Interrupt

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

Stresses 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)

V+ .............................................................................-0.3V to +4V

SCL, SDA, AD0, AD1, AD2, P0–P7 ..........................-0.3V to +6V

INT/O8 .....................................................................-0.3V to +8V

DC Current on P0–P7, INT/O8 ............................................55mA

DC Current on SDA.............................................................10mA

Maximum GND Current ....................................................190mA

Continuous Power Dissipation (T

= +70°C)

16-Pin TSSOP (derate 9.4mW/°C over +70°C) ............754mW

16-Pin QSOP (derate 8.3mW/°C over +70°C)..............666mW

16-Pin QFN (derate 14.7mW/°C over +70°C) ............1176mW

Operating Temperature Range (T

MIN

to T

MAX

)-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+ = 2V to 3.6V, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at V+ = 3.3V, TA = +25°C.)

(Note 1)

Operating Supply Voltage V+ 2 3.6 V

Output Load External Supply Voltage

Standby Current (Interface Idle, PWM Disabled)

Supply Current (Interface Idle, PWM Enabled)

Supply Current (Interface Running, PWM Disabled)

Supply Current (Interface Running, PWM Enabled)

Input High Voltage SDA, SCL, AD0, AD1, AD2, P0–P7

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

EXT

S C L and S D A at V + ; other

d i g i tal i np uts at V + or GN D ;

P WM i ntensi ty contr ol d i sab l ed

S C L and S D A at V + ; other

d i g i tal i np uts at V + or GN D ;

P WM i ntensi ty contr ol enab l ed

inputs at V+ or GND; PWM

intensity control disabled

inputs at V+ or GND; PWM

intensity control enabled

= 400kHz; other digital

SCL

= 400kHz; other digital

SCL

TA = +25°C 1.2 2.3

TA = -40°C to +85°C 2.6

= T

MIN

to T

MAX

TA = +25°C 7 12.1

TA = -40°C to +85°C 13.5

TA = +25°C4076

TA = -40°C to +85°C78

TA = +25°C 51 110

TA = -40°C to +85°C 117

0 5.5 V

0.7 ✕ V+

3.3

14.4

122

µA

Input Low Voltage SDA, SCL, AD0, AD1, AD2, P0–P7

Input Leakage Current SDA, SCL, AD0, AD1, AD2, P0–P7

Input Capacitance SDA, SCL, AD0, AD1, AD2, P0–P7

, IIL0 ≤ input voltage ≤ 5.5V -0.2 +0.2 µA

0.3 ✕ V+

8pF

MAX7315

8-Port I/O Expander with LED Intensity

Control and Interrupt

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(Typical Operating Circuit, V+ = 2V to 3.6V, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at V+ = 3.3V, TA= + 25°C.)

(Note 1)

TIMING CHARACTERISTICS

(Typical Operating Circuit, V+ = 2V to 3.6V, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at V+ = 3.3V, TA = +25°C.)

(Note 1)

Output Low Voltage P0–P7, INT/O8

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

V+ = 2.5V, I

V+ = 3.3V, I

Output Low-Voltage SDA V

PWM Clock Frequency f

OLSDAISINK

PWM

= 20mA

SINK

= 20mA

SINK

= 20mA

SINK

= 6mA 0.4 V

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Serial Clock Frequency f

Bus Free Time Between a STOP and a START Condition

Hold Time, Repeated START Condition t

Repeated START Condition Setup Time t

STOP Condition Setup Time t

Data Hold Time t

Data Setup Time t

SCL Clock Low Period t

SCL Clock High Period t

Rise Time of Both SDA and SCL Signals, Receiving t

Fall Time of Both SDA and SCL Signals, Receiving t

Fall Time of SDA Transmitting t

Pulse Width of Spike Suppressed t

Capacitive Load for Each Bus Line C

SCL

BUF

HD, STA

SU, STA

SU, STO

HD, DAT

SU, DAT

LOW

HIGH

F.TX

(Note 2) 0.9 µs

(Notes 3, 4)

(Notes 3, 5)

(Note 6) 50 ns

(Note 3) 400 pF

TA = +25°C 0.15 0.25

TA = -40°C to +85°C 0.29V+ = 2V, I

= T

MIN

to T

MAX

0.31

TA = +25°C 0.13 0.22

TA = -40°C to +85°C 0.25

= T

MIN

to T

MAX

0.27

TA = +25°C 0.12 0.22

TA = -40°C to +85°C 0.23

= T

MIN

to T

MAX

0.25

32 kHz

400 kHz

1.3 µs

0.6 µs

180 ns

1.3 µs

0.7 µs

200 +

0.1C

200 +

0.1C

200 +

0.1C

300 ns

250 ns

MAX7315

8-Port I/O Expander with LED Intensity Control and Interrupt

4 _______________________________________________________________________________________

TIMING CHARACTERISTICS (continued)

(Typical Operating Circuit, V+ = 2V to 3.6V, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at V+ = 3.3V, TA = +25°C.)

(Note 1)

Note 1: All parameters tested at TA= +25°C. Specifications over temperature are guaranteed by design. Note 2: A master device must provide a hold time of at least 300ns for the SDA signal (referred to V

of the SCL signal) to bridge

the undefined region of SCL’s falling edge.

Note 3: Guaranteed by design. Note 4: C

= total capacitance of one bus line in pF. tRand tFmeasured between 0.3 x VDDand 0.7 x VDD.

Note 5: I

SINK

≤ 6mA. Cb= total capacitance of one bus line in pF. tRand tFmeasured between 0.3 x VDDand 0.7 x VDD.

Note 6: Input filters on the SDA and SCL inputs suppress noise spikes less than 50ns.

STANDBY CURRENT vs. TEMPERATURE

MAX7315 toc01

TEMPERATURE (°C)

STANDBY CURRENT (µA)

1109565 80-10 5 20 35 50-25

-40 125

V+ = 3.6V PWM ENABLED

V+ = 2.7V PWM ENABLED

V+ = 2V PWM DISABLED

V+ = 2.7V PWM DISABLED

V+ = 3.6V PWM DISABLED

V+ = 2V PWM ENABLED

SUPPLY CURRENT vs. TEMPERATURE

(PWM DISABLED; f

SCL

= 400kHz)

MAX7315 toc02

TEMPERATURE (°C)

SUPPLY CURRENT (µA)

1109565 80-10 5 20 35 50-25

-40 125

V+ = 3.6V

V+ = 2.7V

V+ = 2V

SUPPLY CURRENT vs. TEMPERATURE

(PWM ENABLED; f

SCL

= 400kHz)

MAX7315 toc03

TEMPERATURE (°C)

SUPPLY CURRENT (µA)

1109565 80-10 5 20 35 50-25-40 125

V+ = 3.6V

V+ = 2.7V

V+ = 2V

__________________________________________Typical Operating Characteristics

(TA = +25°C, unless otherwise noted.)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Interrupt Valid t

Interrupt Reset t

Output Data Valid t

Input Data Step Time t

Input Data Hold Time t

Figure 10 6.5 µs

Figure 10 1 µs

Figure 10 5 µs

Figure 10 100 ns

Figure 10 1 µs

MAX7315

8-Port I/O Expander with LED Intensity

Control and Interrupt

_______________________________________________________________________________________ 5

Typical Operating Characteristics (continued)

(TA = +25°C, unless otherwise noted.)

PORT OUTPUT LOW VOLTAGE WITH 50mA

LOAD CURRENT vs. TEMPERATURE

0.6

(V)

0.5

V+ = 2V

0.4

0.3

0.2

0.1

PORT OUTPUT LOW VOLTAGE V

SCOPE SHOT OF 2 OUTPUT PORTS

MASTER INTENSITY SET TO 1/15

OUTPUT 1 INDIVIDUAL INTENSITY SET TO 1/16

OUTPUT 2 INDIVIDUAL INTENSITY SET TO 15/16

V+ = 2.7V

V+ = 3.6V

1109565 80-10 5 20 35 50-25-40 125

TEMPERATURE (°C)

MAX7315 toc07

2ms/div

PORT OUTPUT LOW VOLTAGE WITH 20mA

LOAD CURRENT vs. TEMPERATURE

0.6

ALL OUTPUTS LOADED

(V)

0.5

MAX7315 toc04

0.4

0.3

0.2

0.1

PORT OUTPUT LOW VOLTAGE V

-40 125

SCOPE SHOT OF 2 OUTPUT PORTS

MASTER INTENSITY SET TO 14/15

OUTPUT 2V/div

OUTPUT 1 INDIVIDUAL INTENSITY SET TO 1/16

OUTPUT 2V/div

OUTPUT 2 INDIVIDUAL INTENSITY SET TO 14/15

V+ = 2V

V+ = 2.7V

TEMPERATURE (°C)

2ms/div

V+ = 3.6V

MAX7315 toc08

1109580655035205-10-25

MAX7315 toc05

OUTPUT 1, 2V/div

OUTPUT 2, 2V/div

1.050

1.025

1.000

0.975

0.950

PWM CLOCK FREQUENCY

0.925

0.900

0.35

0.30

0.25

0.20

(V)

0.15

0.10

0.05

PWM CLOCK FREQUENCY

vs. TEMPERATURE

V+ = 3.6V

V+ = 2.7V

NORMALIZED TO V+ = 3.3V, TA = +25°C

-40 125 TEMPERATURE (°C)

SINK CURRENT vs. V

V+ = 2V

V+ = 2.7V

V+ = 3.3V

ONLY ONE OUTPUT LOADED

SINK CURRENT (mA)

MAX7315 toc06

V+ = 2V

1109580655035205-10-25

MAX7315 toc09

V+ = 3.6V

5040302010

MAX7315

Functional Overview

The MAX7315 is a general-purpose input/output (GPIO) peripheral that provides eight I/O ports, P0–P7, controlled through an I2C-compatible serial interface. A 9th output-only port, INT/O8, can be configured as an interrupt output or as a general-purpose output port. All output ports sink loads up to 50mA connected to external supplies up to 5.5V, independent of the MAX7315’s

supply voltage. The MAX7315 is rated for a ground current of 190mA, allowing all nine outputs to sink 20mA at the same time. Figure 1 shows the output structure of the MAX7315. The ports default to inputs on power-up.

Port Inputs and Transition Detection

An input ports register reflects the incoming logic levels of the port pins, regardless of whether the pin is defined as an input or an output. Reading the input

8-Port I/O Expander with LED Intensity Control and Interrupt

6 _______________________________________________________________________________________

Pin Description

Figure 1. Simplified Schematic of I/O Ports

QSOP/TSSOP QFN

1, 2, 3 15, 16, 1

4–7, 9–12 2–5, 7–10 P0–P7 Input/Output Ports. P0–P7 are open-drain I/Os rated at 5.5V, 50mA.

8 6 GND Ground. Do not sink more than 190mA into the GND pin.

13 11 INT/O8

14 12 SCL I2C-Compatible Serial Clock Input

15 13 SDA I2C-Compatible Serial Data I/O

16 14 V+

— PAD Exposed pad Exposed Pad on Package Underside. Connect to GND.

DATA FROM

SHIFT REGISTER

DATA FROM

SHIFT REGISTER

WRITE

CONFIGURATION

PULSE

WRITE PULSE

NAME FUNCTION

AD0, AD1,

AD2

Address Inputs. Sets device slave address. Connect to either GND, V+, SCL, or SDA to give 64 logic combinations. See Table 1.

Output Port. Open-drain output rated at 7.0V, 50mA. Configurable as interrupt output or general-purpose output.

Positive Supply Voltage. Bypass V+ to GND with a 0.047µF ceramic capacitor

CONFIGURATION

OUTPUT

PORT

OUTPUT PORT REGISTER DATA

I/O PIN

READ PULSE

INPUT PORT

GND

INPUT PORT REGISTER DATA

TO INT

ports register latches the current-input logic level of the affected eight ports. Transition detection allows all ports configured as inputs to be monitored for changes in their logic status. The action of reading the input ports register samples the corresponding 8 port bits’ input condition. This sample is continuously compared with the actual input conditions. A detected change in input condition causes the INT/O8 interrupt output to go low, if configured as an interrupt output. The interrupt is cleared either automatically if the changed input returns to its original state, or when the input ports register is read.

The INT/O8 pin can be configured as either an interrupt output or as a 9th output port with the same static or blink controls as the other eight ports (Table 4).

Port Output Control and LED Blinking

The blink phase 0 register sets the output logic levels of the eight ports P0–P7 (Table 8). This register controls the port outputs if the blink function is disabled. A duplicate register, the blink phase 1 register, is also used if the blink function is enabled (Table 9). In blink mode, the port outputs can be flipped between using the blink phase 0 register and the blink phase 1 register using software control (the blink flip flag in the configuration register) (Table 4).

PWM Intensity Control

The MAX7315 includes an internal oscillator, nominally 32kHz, to generate PWM timing for LED intensity control. PWM intensity control can be enabled on an output-by-output basis, allowing the MAX7315 to provide any mix of PWM LED drives and glitch-free logic outputs (Table 10). PWM can be disabled entirely, in which case all output ports are static and the MAX7315 operating current is lowest because the internal oscillator is turned off.

PWM intensity control uses a 4-bit master control and 4 bits of individual control per output (Tables 13, 14). The 4-bit master control provides 16 levels of overall intensity control, which applies to all PWM-enabled output ports. The master control sets the maximum pulse width from 1/15 to 15/15 of the PWM time period. The individual settings comprise a 4-bit number further reducing the duty cycle to be from 1/16 to 15/16 of the time window set by the master control.

For applications requiring the same PWM setting for all output ports, a single global PWM control can be used instead of all the individual controls to simplify the control software and provide 240 steps of intensity control (Tables 10 and 13).

Standby Mode

When the serial interface is idle and the PWM intensity control is unused, the MAX7315 automatically enters standby mode. If the PWM intensity control is used, the operating current is slightly higher because the internal PWM oscillator is running. When the serial interface is active, the operating current also increases because the MAX7315, like all I2C slaves, has to monitor every transmission.

Serial Interface

Serial Addressing

The MAX7315 operates as a slave that sends and receives data through an I2C-compatible 2-wire interface. The interface uses a serial data line (SDA) and a serial clock line (SCL) to achieve bidirectional communication between master(s) and slave(s). A master (typically a microcontroller) initiates all data transfers to and from the MAX7315 and generates the SCL clock that synchronizes the data transfer (Figure 2).

The MAX7315 SDA line operates as both an input and an open-drain output. A pullup resistor, typically 4.7kΩ, is required on SDA. The MAX7315 SCL line operates

MAX7315

8-Port I/O Expander with LED Intensity

Control and Interrupt

_______________________________________________________________________________________ 7

Figure 2. 2-Wire Serial Interface Timing Details

SDA

SU,DAT

LOW

SCL

HD,STA

START CONDITION

HIGH

HD,DAT

SU,STA

REPEATED START CONDITION

HD,STA

SU,STO

STOP

CONDITION

BUF

START

CONDITION

MAX7315

only as an input. A pullup resistor, typically 4.7kΩ, is required on SCL if there are multiple masters on the 2wire interface, or if the master in a single-master system has an open-drain SCL output.

Each transmission consists of a START condition (Figure 3) sent by a master, followed by the MAX7315 7-bit slave address plus R/W bit, a register address byte, one or more data bytes, and finally a STOP condition (Figure 3).

Start and Stop Conditions

Both SCL and SDA remain high when the interface is not busy. A master signals the beginning of a transmission with a START (S) condition by transitioning SDA

from high to low while SCL is high. When the master has finished communicating with the slave, it issues a STOP (P) condition by transitioning SDA from low to high while SCL is high. The bus is then free for another transmission (Figure 3).

Bit Transfer

One data bit is transferred during each clock pulse. The data on SDA must remain stable while SCL is high (Figure 4).

Acknowledge

The acknowledge bit is a clocked 9th bit that the recipient uses to handshake receipt of each byte of data (Figure 5). Thus, each byte transferred effectively requires 9 bits. The master generates the 9th clock pulse, and the recipient pulls down SDA during the acknowledge clock pulse so the SDA line is stable low during the high period of the clock pulse. When the master is transmitting to the MAX7315, the device generates the acknowledge bit because the MAX7315 is the recipient. When the MAX7315 is transmitting to the master, the master generates the acknowledge bit because the master is the recipient.

Slave Address

The MAX7315 has a 7-bit long slave address (Figure 6). The eighth bit following the 7-bit slave address is the R/W bit. The R/W bit is low for a write command, high for a read command.

The slave address bits A6 through A0 are selected by the address inputs AD0, AD1, and AD2. These pins can be connected to GND, V+, SDA, or SCL. The MAX7315 has 64 possible slave addresses (Table 1) and, therefore, a maximum of 64 MAX7315 devices can be controlled independently from the same interface.

Message Format for Writing the MAX7315

A write to the MAX7315 comprises the transmission of the MAX7315’s slave address with the R/W bit set to zero, followed by at least 1 byte of information. The first byte of information is the command byte. The command byte determines which register of the MAX7315 is to be written to by the next byte, if received (Table 2). If a STOP condition is detected after the command byte is received, then the MAX7315 takes no further action beyond storing the command byte.

8-Port I/O Expander with LED Intensity Control and Interrupt

8 _______________________________________________________________________________________

Figure 3. Start and Stop Conditions

Figure 4. Bit Transfer

Figure 5. Acknowledge

Figure 6. Slave Address

SDA

SCL

START

CONDITION

SDA

SCL

DATA LINE STABLE;

DATA VALID

START

CONDITION

SCL

SDA BY

TRANSMITTER

SDA BY

RECEIVER

CHANGE OF DATA

ALLOWED

CLOCK PULSE

FOR ACKNOWLEDGE

12 89

STOP

CONDITION

SDA

MSB

SCL

LSB

ACKA4 A1A6 A3 A0A2 R/W

MAX7315

8-Port I/O Expander with LED Intensity

Control and Interrupt

_______________________________________________________________________________________ 9

Table 1. MAX7315 I2C Slave Address Map

PIN AD2 PIN AD1 PIN AD0

A6 A5 A4 A3 A2 A1 A0

GND SCL GND0010000

GND SCL V+ 0010001

GNDSDAGND0010010

GNDSDA V+ 0010011

V+ SCL GND0010100

V+ SCL V+ 0010101

V+ SDAGND0010110

V+ SDA V+ 0010111

GND SCL SCL0011000

GND SCL SDA 0011001

GNDSDA SCL 0011010

GNDSDA SDA0011011

V+ SCL SCL 0011100

V+ SCL SDA0011101

V+ SDA SCL 0011110

V+ SDA SDA0011111

GNDGNDGND0100000

GNDGND V+ 0100001

GND V+ GND0100010

GND V+ V+ 0100011

V+ GNDGND0100100

V+ GND V+ 0100101

V+ V+ GND0100110

V+ V+ V+ 0100111

DEVICE ADDRESS

GNDGND SCL 0101000

GNDGNDSDA0101001

GND V+ SCL 0101010

GND V+ SDA0101011

V+ GND SCL 0101100

V+ GNDSDA0101101

V+ V+ SCL 0101110

V+ V+ SDA0101111

MAX7315

8-Port I/O Expander with LED Intensity Control and Interrupt

10 ______________________________________________________________________________________

Table 1. MAX7315 I2C Slave Address Map (continued)

PIN AD2 PIN AD1 PIN AD0

SCL SCL GND1010000

SCL SCL V+ 1010001

SCL SDA GND1010010

SCL SDA V+ 1010011

SDA SCL GND1010100

SDA SCL V+ 1010101

SDA SDA GND1010110

SDA SDA V+ 1010111

SCL SCL SCL1011000

SCL SCL SDA 1011001

SCL SDA SCL 1011010

SCL SDA SDA1011011

SDA SCL SCL 1011100

SDA SCL SDA 1011101

SDA SDA SCL 1011110

SDA SDA SDA 1011111

SCL GNDGND1100000

SCL GND V+ 1100001

SCL V+ GND1100010

SCL V+ V+ 1100011

SDAGNDGND1100100

SDAGND V+ 1100101

SDA V+ GND1100110

SDA V+ V+ 1100111

A6 A5 A4 A3 A2 A1 A0

DEVICE ADDRESS

SCL GND SCL 1101000

SCL GNDSDA1101001

SCL V+ SCL 1101010

SCL V+ SDA1101011

SDAGND SCL 1101100

SDAGNDSDA1101101

SDA V+ SCL 1101110

SDA V+ SDA 1101111

Any bytes received after the command byte are data bytes. The first data byte goes into the internal register of the MAX7315 selected by the command byte (Figure

8). If multiple data bytes are transmitted before a STOP condition is detected, these bytes are generally stored in subsequent MAX7315 internal registers because the command byte address autoincrements (Table 2). A diagram of a write to the output ports registers (blink phase 0 register or blink phase 1 register) is given in Figure 10.

Message Format for Reading

The MAX7315 is read using the MAX7315’s internally stored command byte as an address pointer the same way the stored command byte is used as an address pointer for a write. The pointer autoincrements after each data byte is read using the same rules as for a write (Table 2). Thus, a read is initiated by first configuring the MAX7315’s command byte by performing a write (Figure 7). The master can now read n consecu-

tive bytes from the MAX7315 with the first data byte being read from the register addressed by the initialized command byte. When performing read-after-write verification, remember to reset the command byte’s address because the stored command byte address has been autoincremented after the write (Table 2). A diagram of a read from the input ports register is shown in Figure 10 reflecting the states of the ports.

Operation with Multiple Masters

If the MAX7315 is operated on a 2-wire interface with multiple masters, a master reading the MAX7315 should use a repeated start between the write, which sets the MAX7315’s address pointer, and the read(s) that takes the data from the location(s) (Table 2). This is because it is possible for master 2 to take over the bus after master 1 has set up the MAX7315’s address pointer but before master 1 has read the data. If master 2 subsequently changes the MAX7315’s address pointer, then master 1’s delayed read can be from an unexpected location.

MAX7315

8-Port I/O Expander with LED Intensity

Control and Interrupt

______________________________________________________________________________________ 11

Figure 8. Command and Single Data Byte Received

Figure 9. n Data Bytes Received

Figure 7. Command Byte Received

COMMAND BYTE IS STORED ON RECEIPT OF

ACKNOWLEDGE FROM MAX7315

SAA

HOW COMMAND BYTE AND DATA BYTE MAP INTO

SAAAP0SLAVE ADDRESS COMMAND BYTE DATA BYTE

HOW COMMAND BYTE AND DATA BYTE MAP INTO

SAAAP0SLAVE ADDRESS COMMAND BYTE DATA BYTE

MAX7315'S REGISTERS

ACKNOWLEDGE FROM MAX7315

R/W

MAX7315'S REGISTERS

ACKNOWLEDGE FROM MAX7315

R/W

STOP CONDITION

0SLAVE ADDRESS COMMAND BYTE

R/W

ACKNOWLEDGE FROM MAX7315 ACKNOWLEDGE FROM MAX7315

D15 D14 D13 D12 D11 D10 D9 D8 D1 D0D3 D2D5 D4D7 D6

ACKNOWLEDGE FROM MAX7315 ACKNOWLEDGE FROM MAX7315

D15 D14 D13 D12 D11 D10 D9 D8 D1 D0D3 D2D5 D4D7 D6

D15 D14 D13 D12 D11 D10 D9 D8

ACKNOWLEDGE FROM MAX7315

AUTOINCREMENT MEMORY ADDRESS

BYTE

BYTES

MAX7315

Command Address Autoincrementing

The command address stored in the MAX7315 circulates around grouped register functions after each data byte is written or read (Table 2).

Device Reset

If a device reset input is needed, consider the MAX7316. The MAX7316 includes a RST input, which clears any transaction to or from the MAX7316 on the serial interface and configures the internal registers to the same state as a power-up reset.

Detailed Description

Initial Power-Up

On power-up all control registers are reset and the MAX7315 enters standby mode (Table 3). Power-up status makes all ports into inputs and disables both the PWM oscillator and blink functionality.

Configuration Register

The configuration register is used to configure the PWM intensity mode, interrupt, and blink behavior, operate the INT/O8 output, and read back the interrupt status (Table 4).

8-Port I/O Expander with LED Intensity Control and Interrupt

12 ______________________________________________________________________________________

Figure 10. Read, Write, and Interrupt Timing Diagrams

WRITE TO OUTPUT PORTS REGISTERS (BLINK PHASE 0 REGISTERS/BLINK PHASE 1 REGISTERS)

SCL

123456789

SLAVE ADDRESS

SDA

SA6A5A4A3A2A1A00 A0000000

COMMAND BYTE

1A A AP

MSB LSBDATA1

MSB LSBDATA2

START CONDITION

P7–P0

READ FROM INPUT PORTS REGISTERS

SCL

123456789

SLAVE ADDRESS

SDA

SA6A5A4A3A2A1A0 1 A

START CONDITION

P7–P0

INTERRUPT VALID/RESET

SCL

123456789

SLAVE ADDRESS

SDA

S A6A5A4A3A2A1A0 1 A

START CONDITION

P7–P0

INT

DATA 1

ACKNOWLEDGE FROM SLAVE

R/W

COMMAND BYTE

MSB LSBDATA1

ACKNOWLEDGE FROM SLAVE

R/W

DATA 1 DATA 2 D ATA3 DATA 4

R/W

COMMAND BYTE

MSB LSBDATA2 MSB LSBDATA4

ACKNOWLEDGE FROM SLAVE

DATA 2

ACKNOWLEDGE FROM SLAVE ACKNOWLEDGE FROM SLAVE STOP

ANA

MSB LSBDATA4

ACKNOWLEDGE FROM MASTER

ANA

ACKNOWLEDGE FROM MASTER

DATA 3

DATA1 VALID

STOP CONDITION

NO ACKNOWLEDGE FROM MASTER

STOP CONDITION

NO ACKNOWLEDGE FROM MASTER

CONDITION

DATA2 VALID

Ports Configuration

The 8 I/O ports P0 through P7 can be configured to any combination of inputs and outputs using the ports configuration register (Table 5). The INT/O8 output can also be configured as an extra general-purpose output using the configuration register (Table 4).

Input Ports

The input ports register is read only (Table 6). It reflect the incoming logic levels of the ports, regardless of whether the port is defined as an input or an output by the ports configuration register. Reading the input ports register latches the current-input logic level of the affected eight ports. A write to the input ports register is ignored.

Transition Detection

All ports configured as inputs are always monitored for changes in their logic status. The action of reading the input ports register or writing to the configuration register samples the corresponding 8 port bits’ input condition (Tables 4, 6). This sample is continuously compared with the actual input conditions. A detected change in input condition causes an interrupt condition. The interrupt is cleared either automatically if the changed input returns to its original state, or when the input ports register is read, updating the compared data (Figure 10). Randomly changing a port from an output to an input may cause a false interrupt to occur if the state of the input does not match the content of the input ports register. The interrupt status is available as the interrupt flag INT in the configuration register (Table 4).

The input status of all ports is sampled immediately after power-up as part of the MAX7315’s internal initial-

ization, so if all the ports are pulled to valid logic levels at that time an interrupt does not occur at power-up.

INT

/O8 Output

The INT/O8 output pin can be configured as either the INT output that reflects the interrupt flag logic state or as

a general-purpose output O8. When used as a generalpurpose output, the INT/O8 pin has the same blink and PWM intensity control capabilities as the other ports.

Set the interrupt enable I bit in the configuration register to configure INT/O8 as the INT output (Table 4). Clear interrupt enable to configure INT/O8 as the O8. O8 logic state is set by the 2 bits O1 and O0 in the configuration register. O8 follows the rules for blinking selected by the blink enable flag E in the configuration register. If blinking is disabled, then interrupt output control O0 alone sets the logic state of the INT/O8 pin. If blinking is enabled, then both interrupt output controls O0 and O1 set the logic state of the INT/O8 pin according to the blink phase. PWM intensity control for O8 is set by the 4 global intensity bits in the master, O8 intensity register (Table 13).

Blink Mode

In blink mode, the output ports can be flipped between using either the blink phase 0 register or the blink phase 1 register. Flip control is by software control (the blink flip flag B in the configuration register) (Table 4). If hardware flip control is needed, consider the MAX7316, which includes a BLINK input, as well as software control.

The blink function can be used for LED effects by programming different display patterns in the two sets of

MAX7315

8-Port I/O Expander with LED Intensity

Control and Interrupt

______________________________________________________________________________________ 13

Table 2. Register Address Map

Read input ports 0x00 0x00 (no change)

Blink phase 0 outputs 0x01 0x01 (no change)

Ports configuration 0x03 0x03 (no change)

Blink phase 1 outputs 0x09 0x09 (no change)

Master, O8 intensity 0x0E 0x0E (no change)

Configuration 0x0F 0x0F (no change)

Outputs intensity P1, P0 0x10 0x11

Outputs intensity P3, P2 0x11 0x12

Outputs intensity P5, P4 0x12 0x13

Outputs intensity P7, P6 0x13 0x10

ADDRESS CODE

(HEX)

AUTOINCREMENT

ADDRESS

MAX7315

8-Port I/O Expander with LED Intensity Control and Interrupt

14 ______________________________________________________________________________________

Table 3. Power-Up Configuration

Table 4. Configuration Register

ADDRESS

CODE

(HEX)

D7 D6 D5 D4 D3 D2 D1 D0

CONFIGURATION

R/W

INTERRUPT

STATUS

—

INTERRUPT

OUTPUT

CONTROL

AS GPO

INTERRUPT

ENABLE

GLOBAL

INTENSITY

BLINK FLIP

BLINK

ENABLE

Write device configuration

Read-back device configuration

O0 I G B E

Disable blink

XXXXXXX0

Enable blink

XXXXXXX1

XXXXXX01

Flip blink register (see text)

XXXXXX11

Disable global intensity control—intensity is set by registers 0x10–0x13 for ports P0

through P7 when configured as outputs,

and by D3–D7 of register 0x0E for INT/O8

when INT/O8 pin is configured as an

output port

XXXXX0 XX

Enable global intensity control—intensity

for all ports configured as outputs is set

by D3–D0 of register 0x0E

0x0F

XXXXX1 XX

Blink phase 0 outputs P7–P0 High-impedance outputs 0x01 1 1 1 1 1 1 1 1

Ports configuration P7–P0 Ports P7–P0 are inputs 0x03 1 1 1 1 1 1 1 1

Blink phase 1 outputs P7–P0 High-impedance outputs 0x09 1 1 1 1 1 1 1 1

Master, O8 intensity

Configuration

Outputs intensity P1, P0 P1, P0 are static logic outputs 0x10 1 1 1 1 1 1 1 1

Outputs Intensity P3, P2 P3, P2 are static logic outputs 0x11 1 1 1 1 1 1 1 1

Outputs intensity P5, P4 P5, P4 are static logic outputs 0x12 1 1 1 1 1 1 1 1

Outputs intensity P7, P6 P7, P6 are static logic outputs 0x13 1 1 1 1 1 1 1 1

PWM oscillator is disabled;

O8 is static logic output

INT/O8 is interrupt output;

blink is disabled;

global intensity is enabled

ADDRESS

CODE (HEX)

0x0E 0 0 0 0 1 1 1 1

0x0F 0 0 0 0 1 1 0 0

D7 D6 D5 D4 D3 D2 D1 D0

—

INT

output port registers, and using the software or hardware controls to flip between the patterns.

If the blink phase 1 register is written with 0xFF, then the BLINK input can be used as a hardware disable to, for example, instantly turn off an LED pattern programmed into the blink phase 0 register. This technique can be further extended by driving the BLINK input with a PWM signal to modulate the LED current to provide fading effects.

The blink mode is enabled by setting the blink enable flag E in the configuration register (Table 4). When blink mode is enabled, the state of the blink flip flag sets the phase, and the output ports are set by either the blink

phase 0 register or the blink phase 1 register (Table 7).

The blink mode is disabled by clearing the blink enable flag E in the configuration register (Table 4). When blink mode is disabled, the blink phase 0 register alone controls the output ports.

Blink Phase Registers

When the blink function is disabled, the blink phase 0 register sets the logic levels of the 8 ports (P0 through P7) when configured as outputs (Table 8). A duplicate register called the blink phase 1 register is also used if the blink function is enabled (Table 9). A logic high sets the appropriate output port high impedance, while a logic low makes the port go low.

MAX7315

8-Port I/O Expander with LED Intensity

Control and Interrupt

______________________________________________________________________________________ 15

Table 4. Configuration register (continued)

ADDRESS

CODE (HEX)

D7 D6 D5 D4 D3 D2 D1 D0

CONFIGURATION

R/W

INTERRUPT

STATUS

—

INTERRUPT

OUTPUT

CONTROL

AS GPO

INTERRUPT

ENABLE

GLOBAL

INTENSITY

BLINK FLIP

BLINK

ENABLE

Disable data change interrupt—INT/O8

output is controlled by the O0 and O1 bits

O0 I G B E

Enable data change interrupt—INT/O8

output is controlled by port input data

change

XXXX1 XXX

INT/O8 output is low (blink is disabled)

XXX00XX0

INT/O8 output is high impedance (blink is

disabled)

XXX10XX0

INT/O8 outp ut i s l ow d ur i ng b l i nk p hase 0

XXX00XX1

INT/O8 output is high impedance during

blink phase 0

XXX10XX1

INT/O8 outp ut i s l ow d ur i ng b l i nk p hase 1

XX0 X 0 XX1

INT/O8 output is high impedance during

blink phase 1

XX1 X 0 XX1

Read-back data change interrupt status

—data change is not detected, and

INT/O8 output is high when interrupt

enable (I bit) is set

0 0XXXXXX

Read-back data change interrupt status —data change is detected, and INT/O8

output is low when interrupt enable (I bit)

is set

0x0F

1 0XXXXXX

— INT

—

MAX7315

Reading a blink phase register reads the value stored in the register, not the actual port condition. The port output itself may or may not be at a valid logic level, depending on the external load connected.

The 9th output, O8, is controlled through 2 bits in the configuration register, which provide the same static or blink control as the other 8 output ports.

PWM Intensity Control

The MAX7315 includes an internal oscillator, nominally 32kHz, to generate PWM timing for LED intensity control or other applications such as PWM trim DACs. PWM can be disabled entirely for all the outputs. In this case, all outputs are static and the MAX7315 operating current is lowest because the internal PWM oscillator is turned off.

The MAX7315 can be configured to provide any combination of PWM outputs and glitch-free logic outputs. Each PWM output has an individual 4-bit intensity control (Table 14). When all outputs are to be used with the same PWM setting, the outputs can be controlled together instead using the global intensity control (Table 13). Table 10 shows how to set up the MAX7315 to suit a particular application.

PWM Timing

The PWM control uses a 240-step PWM period, divided into 15 master intensity timeslots. Each master intensity timeslot is divided further into 16 PWM cycles (Figure 11).

The master intensity operates as a gate, allowing the individual output settings to be enabled from 1 to 15 timeslots per PWM period (Figures 12, 13, 14) (Table 13).

Each output’s individual 4-bit intensity control only operates during the number of timeslots gated by the

master intensity. The individual controls provide 16 intensity settings from 1/16 through 16/16 (Table 14).

Figures 15, 16, and 17 show examples of individual intensity control settings. The highest value an individual or global setting can be set to is 16/16. This setting forces the output to ignore the master control, and follow the logic level set by the appropriate blink phase register bit. The output becomes a glitch-free static output with no PWM.

Using PWM Intensity Controls with Blink Disabled

When blink is disabled (Table 7), the blink phase 0 register specifies each output’s logic level during the PWM on-time (Table 8). The effect of setting an output’s blink phase 0 register bit to 0 or 1 is shown in Table 11. With its output bit set to zero, an LED can be controlled with 16 intensity settings from 1/16th duty through fully on, but cannot be turned fully off using the PWM intensity control. With its output bit set to 1, an LED can be controlled with 16 intensity settings from fully off through 15/16th duty.

8-Port I/O Expander with LED Intensity Control and Interrupt

16 ______________________________________________________________________________________

Table 5. Ports Configuration Register

Table 6. Input Ports Register

Table 7. Blink Controls

Ports configuration

(1 = input, 0 = output)

Read-back ports configuration 1

ADDRESS

Read input ports 1 0x00 IP7 IP6 IP5 IP4 IP3 IP2 IP1 IP0

ADDRESS

CODE (HEX)

0x03 OP7 OP6 OP5 OP4 OP3 OP2 OP1 OP0

CODE (HEX)

D7 D6 D5 D4 D3 D2 D1 D0

BLINK

ENABLE

FLAG E

0 X Disabled

BLINK

FLIP

FLAG B

BLINK

FUNCTION

Enabled

OUTPUT

REGISTERS

USED

Blink phase 0

Blink phase 1

Using PWM Intensity Controls with Blink Enabled

When blink is enabled (Table 7), the blink phase 0 register and blink phase 1 register specify each output’s logic level during the PWM on-time during the respective blink phases (Tables 8 and 9). The effect of setting an output’s blink phase X register bit to 0 or 1 is shown in Table 12. LEDs can be flipped between either directly on and off, or between a variety of high/low PWM intensities.

Global/O8 Intensity Control

The 4 bits used for output O8’s PWM individual intensity setting also double as the global intensity control (Table 13). Global intensity simplifies the PWM settings when the application requires them all to be the same, such as for backlight applications, by replacing the 9 individual settings with 1 setting. Global intensity is enabled with the global intensity flag G in the configuration register (Table 4). When global PWM control is used, the 4 bits of master intensity and 4 bits of O8 intensity effectively combine to provide an 8 bit, 240step intensity control applying to all outputs.

It is not possible to apply global PWM control to a subset of the ports, and use the others as logic outputs. To mix static logic outputs and PWM outputs, individual PWM control must be selected (Table 10).

Applications Information

Output Level Translation

The open-drain output architecture allows the ports to level translate the outputs to higher or lower voltages than the MAX7315 supply. An external pullup resistor can be used on any output to convert the high-impedance logic-high condition to a positive voltage level. The resistor can be connected to any voltage up to

5.5V. For interfacing CMOS inputs, a pullup resistor value of 220kΩ is a good starting point. Use a lower resistance to improve noise immunity, in applications where power consumption is less critical, or where a faster rise time is needed for a given capacitive load.

Compatibility with PCA9534 and

PCA9554(A)

The MAX7315 is pin compatible and software compatible with PCA9534, and its variants PCA9554 and PCA9554A. However, some PCA9534 and PCA9554(A) functions are not implemented in the MAX7315, and the MAX7315's PWM and blink functionality is not supported in the PCA9534 and PCA9554(A). Software compatibility is clearly not 100%, but the MAX7315 was designed so the subset (omitted) features default to the same powerup behavior as the PCA9534 and PCA9554(A), and the superset features do not use existing registers in a different way. In practice, many applications can use the MAX7315 as a drop-in replacement for the PCA9534 or PCA9554(A) with no software change.

Driving LED Loads

When driving LEDs, a resistor in series with the LED must be used to limit the LED current to no more than 50mA. Choose the resistor value according to the following formula:

LED

= (V

SUPPLY

- V

LED

- VOL) / I

LED

where:

LED

is the resistance of the resistor in series with the LED (Ω). V

SUPPLY

is the supply voltage used to drive the LED (V).

LED

is the forward voltage of the LED (V).

MAX7315

8-Port I/O Expander with LED Intensity

Control and Interrupt

______________________________________________________________________________________ 17

Table 8. Blink Phase 0 Register

Table 9. Blink Phase 1 Register

Write outputs phase 0 0

Read-back outputs phase 0 1

Write outputs phase 1 0

Read-back outputs phase 1 1

ADDRESS

CODE (HEX)

0x01 OP7 OP6 OP5 OP4 OP3 OP2 OP1 OP0

ADDRESS

CODE (HEX)

0x09 OP7 OP6 OP5 OP4 OP3 OP2 OP1 OP0

D7 D6 D5 D4 D3 D2 D1 D0

MAX7315

8-Port I/O Expander with LED Intensity Control and Interrupt

18 ______________________________________________________________________________________

Table 10. PWM Application Scenarios

Figure 11. PWM Timing

Figure 12. Master Set to 1/15

Figure 14. Master Set to 15/15

Figure 13. Master Set to 14/15

APPLICATION RECOMMENDED CONFIGURATION

All outputs static without PWM

A mix of static and PWM outputs, with PWM outputs using different PWM settings

A mix of static and PWM outputs, with PWM outputs all using the same PWM setting

All outputs PWM using the same PWM setting

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 14 15 1 2

Set the master, O8 intensity register 0x0E to any value from 0x00 to 0x0F. The global intensity G bit in the configuration register is don't care. The output intensity registers 0x10 through 0x13 are don't care.

Set the master, O8 intensity register 0x0E to any value from 0x10 to 0xFF. Clear global intensity G bit to 0 in the configuration register to disable global intensity control. For the static outputs, set the output intensity value to 0xF. For the PWM outputs, set the output intensity value in the range 0x0 to 0xE.

As above. Global intensity control cannot be used with a mix of static and PWM outputs, so write the individual intensity registers with the same PWM value.

Set the master, O8 intensity register 0x0E to any value from 0x10 to 0xFF. Set global intensity G bit to 1 in the configuration register to enable global intensity control. The master, O8 intensity register 0x0E is the only intensity register used. The output intensity registers 0x10 through 0x13 are don't care.

ONE PWM PERIOD IS 240 CYCLES OF THE 32kHz PWM

OSCILLATOR. A PWM PERIOD CONTAINS 15 MASTER

INTENSITY TIMESLOTS

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 15 16 1 2

EACH MASTER INTENSITY

TIMESLOT CONTAINS 16

PWM CYCLES

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 14 15 2 1

MAX7315

8-Port I/O Expander with LED Intensity

Control and Interrupt

______________________________________________________________________________________ 19

Figure 16. Individual (or Global) Set to 15/16

Figure 15. Individual (or Global) Set to 1/16

Figure 17. Individual (or Global) Set to 16/16

Table 11. PWM Intensity Settings (Blink Disabled)

MASTER INTENSITY TIMESLOT

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

MASTER INTENSITY TIMESLOT

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

MASTER INTENSITY TIMESLOT CONTROL IS IGNORED

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

OUTPUT

(OR

GLOBAL)

INTENSITY

SETTING

0x0 1/16 15/16 Lowest PWM intensity 15/16 1/16 Highest PWM intensity

0x1 2/16 14/16 14/16 2/16

0x2 3/16 13/16 13/16 3/16

0x3 4/16 12/16 12/16 4/16

0x4 5/16 11/16 11/16 5/16

0x5 6/16 10/16 10/16 6/16

0x6 7/16 9/16 9/16 7/16

0x7 8/16 8/16 8/16 8/16

0x8 9/16 7/16 7/16 9/16

0x9 10/16 6/16 6/16 10/16

0xA 11/16 5/16 5/16 11/16

0xB 12/16 4/16 4/16 12/16

0xC 13/16 3/16 3/16 13/16

0xD 14/16 2/16

0xE 15/16 1/16 Highest PWM intensity 1/16 15/16 Lowest PWM intensity

0xF Static low Static low

PWM DUTY CYCLE

OUTPUT BLINK PHASE 0

LOW TIME HIGH TIME

LED BEHAVIOR WHEN

OUTPUT BLINK PHASE 0

(LED IS ON WHEN

OUTPUT IS LOW)

 Increasing PWM intensity

Full intensity, no PWM

(LED on continuously)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

NEXT MASTER INTENSITY TIMESLOT

PWM DUTY CYCLE

OUTPUT BLINK PHASE 0

LOW TIME HIGH TIME

2/16 14/16

Static high

impedance

Static high

impedance

LED BEHAVIOR WHEN

OUTPUT BLINK PHASE 0

OUTPUT IS LOW)

LED off continuously

Increasing PWM intensity 

MAX7315

VOLis the output low voltage of the MAX7313 when sinking I

LED

(V).

LED

is the desired operating current of the LED (A).

For example, to operate a 2.2V red LED at 14mA from a 5V supply, R

LED

= (5 - 2.2 - 0.25) / 0.014 = 182Ω.

Driving Load Currents Higher than 50mA

The MAX7315 can be used to drive loads drawing more than 50mA, like relays and high-current white LEDs, by paralleling outputs. Use at least one output per 50mA of load current; for example, a 5V 330mW relay draws 66mA and needs two paralleled outputs to drive it. Ensure that the paralleled outputs chosen are controlled by the same blink phase register, i.e., select outputs from the P0 through P7 range. This way, the paralleled outputs are turned on and off together. Do not use output O8 as part of a load-sharing design. O8 cannot be switched at the same time as any of the other outputs because it is controlled by a different register.

The MAX7315 must be protected from the negative voltage transient generated when switching off induc-

tive loads, such as relays, by connecting a reversebiased diode across the inductive load (Figure 18). The peak current through the diode is the inductive load’s operating current.

Power-Supply Considerations

The MAX7315 operates with a power-supply voltage of 2V to 3.6V. Bypass the power supply to GND with at least 0.047µF as close to the device as possible.

Chip Information

TRANSISTOR COUNT: 17,611

PROCESS: BiCMOS

8-Port I/O Expander with LED Intensity Control and Interrupt

20 ______________________________________________________________________________________

Table 12. PWM Intensity Settings (Blink Enabled)

OUTPUT

(OR

GLOBAL)

INTENSITY

SETTING

0x0 1/16 15/16 15/16 1/16

0x1 2/16 14/16 14/16 2/16

0x2 3/16 13/16 13/16 3/16

0x3 4/16 12/16 12/16 4/16

0x4 5/16 11/16 11/16 5/16

0x5 6/16 10/16 10/16 6/16

0x6 7/16 9/16 9/16 7/16

0x7 8/16 8/16 8/16 8/16 Output is half intensity during both blink phases

0x8 9/16 7/16 7/16 9/16

0x9 10/16 6/16 6/16 10/16

0xA 11/16 5/16 5/16 11/16

0xB 12/16 4/16 4/16 12/16

0xC 13/16 3/16 3/16 13/16

0xD 14/16 2/16 2/16 14/16

0xE 15/16 1/16 1/16 15/16

0xF Static low Static low

PWM DUTY CYCLE

OUTPUT BLINK

PHASE X

LOW TIME

HIGH TIME

PWM DUTY CYCLE

OUTPUT BLINK

PHASE X

LOW TIME

Static high

impedance

HIGH TIME

Static high

impedance

EXAMPLES OF LED BLINK BEHAVIOR

(LED IS ON WHEN OUTPUT IS LOW)

BLINK PHASE 0

BLINK PHASE 1

P hase 0: LE D on at l ow i ntensi ty

P hase 1: LE D on at hi g h i ntensi ty

P hase 0: LE D on at hi g h i ntensi ty

P hase 1: LE D on at l ow i ntensi ty

Phase 0: LED on continuously Phase 1: LED off continuously

BLINK PHASE 0

BLINK PHASE 1

P hase 0: LE D on at hi g h i ntensi ty

P hase 1: LE D on at l ow i ntensi ty

P hase 0: LE D on at l ow i ntensi ty

P hase 1: LE D on at hi g h i ntensi ty

Phase 0: LED off continuously Phase 1: LED on continuously

MAX7315

8-Port I/O Expander with LED Intensity

Control and Interrupt

______________________________________________________________________________________________________ 21

Table 13. Master, O8 Intensity Register

MASTER AND GLOBAL INTENSITY

Write master and global intensity 0

Read back master and global intensity 1

Master intensity duty cycle is 0/15 (off);

internal oscillator is disabled;

all outputs will be static with no PWM

Master intensity duty cycle is 1/15 — 0001————

Master intensity duty cycle is 2/15 — 0010————

Master intensity duty cycle is 3/15 — 0011————

— — ————————

Master intensity duty cycle is 13/15 — 1101————

Master intensity duty cycle is 14/15 — 1110————

Master intensity duty cycle is 15/15 (full) — 1111————

O8 intensity duty cycle is 1/16 — ———— 0000

O8 intensity duty cycle is 2/16 — ———— 0001

O8 intensity duty cycle is 3/16 — ———— 0010

— — ————————

O8 intensity duty cycle is 14/16 — ———— 1101

O8 intensity duty cycle is 15/16 — ———— 1110

O8 intensity duty cycle is 16/16

(static output, no PWM)

ADDRESS

CODE

R/W

(HEX)

— 0000————

0X0E

—

D7 D6 D5 D4 D3 D2 D1 D0

MSB LSB MSB LSB

MASTER INTENSITY O8 INTENSITY

M3 M2 M1 M0 G3 G2 G1 G0

———— 1111

MAX7315

8-Port I/O Expander with LED Intensity Control and Interrupt

22 ______________________________________________________________________________________

Table 14. Output Intensity Registers

ADDRESS

CODE

(HEX)

D7 D6 D5 D4 D3 D2 D1 D0

LSB

OUTPUTS P1, P0 INTENSITY

R/W

OUTPUT P1 INTENSITY OUTPUT P0 INTENSITY

Write output P1, P0 intensity

Read back output P1, P0 intensity

P0I0

Output P1 intensity duty cycle is 1/16

0000————

Output P1 intensity duty cycle is 2/16

0001————

Output P1 intensity duty cycle is 3/16

0010————

—

————————

Output P1 intensity duty cycle is 14/16

1101————

Output P1 intensity duty cycle is 15/16

1110————

Output P1 intensity duty cycle is 16/16

(static logic level, no PWM)

1111————

Output P0 intensity duty cycle is 1/16

———— 0000

Output P0 intensity duty cycle is 2/16

———— 0001

Output P0 intensity duty cycle is 3/16

———— 0010

—

————————

Output P0 intensity duty cycle is 14/16

———— 1101

Output P0 intensity duty cycle is 15/16

———— 1110

Output P0 intensity duty cycle is 16/16

(static logic level, no PWM)

0X10

———— 1111

LSB

OUTPUTS P3, P2 INTENSITY

OUTPUT P3 INTENSITY OUTPUT P2 INTENSITY

Write output P3, P2 intensity

Read back output P3, P2 intensity

0x11

P2I0

LSB

OUTPUTS P5, P4 INTENSITY

OUTPUT P5 INTENSITY OUTPUT P4 INTENSITY

Write output P5, P4 intensity

Read back output P5, P4 intensity

0x12

P4I0

LSB

OUTPUTS P7, P6 INTENSITY

OUTPUT P7 INTENSITY OUTPUT P6 INTENSITY

Write output P7, P6 intensity

Read back output P7, P6 intensity

0x13

P6I0

OUTPUT O8 INTENSITY See the master, O8 intensity register (Table 13).

MSB LSB MSB

—

P1I3 P1I2 P1I1 P1I0 P0I3 P0I2 P0I1

MSB LSB MSB

P3I3 P3I2 P3I1 P3I0 P2I3 P2I2 P2I1

MSB LSB MSB

P5I3 P5I2 P5I1 P5I0 P4I3 P4I2 P4I1

MSB LSB MSB

P7I3 P7I2 P7I1 P7I0 P6I3 P6I2 P6I1

MAX7315

8-Port I/O Expander with LED Intensity

Control and Interrupt

______________________________________________________________________________________ 23

Table 15. MAX7311, PCA9535, and PCA9555 Register Compatibility

Figure 18. Diode-Protected Switching Inductive Load

Pin Configurations (continued)

PCA9534,

PCA9554(A)

ADDRESS MAX7313 IMPLEMENTATION

Inputs 0x00 Inputs registers Implemented Same functionality

Outputs 0x01 Blink phase 0 registers Implemented Same functionality

Polarity inversion 0x02

Not implemented; register writes are ignored; register reads return 0x00

Configuration 0x03 Ports configuration registers Not implemented Same functionality

No registers 0x0B Blink phase 1 registers Not implemented

No register 0x0E Master and global/O8 intensity register Not implemented

No register 0x0F Configuration register Not implemented

No registers 0x10–0x13 Outputs intensity registers Not implemented

2V TO 3.6V

0.047µF

µC

SDA

SCL

V+

SDA

MAX7315

SCL

I/O

INT/O8

AD0 AD1 AD2

GND

P0 P1

BAS16

P2 P3 P4 P5 P6 P7

TOP VIEW

MAX7311, PCA9535,

PCA9555

COMMENTS

IMPLEMENTATION

Implemented; power-up default is 0x00

If polarity inversion feature is unused, MAX7313 defaults to correct state

Power-up default disables the blink and intensity (PWM) features

AD0

AD1

AD2

GND

MAX7315AEE

MAX7315AUE

QSOP/TSSOP

V+

SDA

SCL

INT/O8

MAX7315

8-Port I/O Expander with LED Intensity Control and Interrupt

24 ______________________________________________________________________________________

Package Information

(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages

QSOP.EPS

PACKAGE OUTLINE, QSOP .150", .025" LEAD PITCH

21-0055

MAX7315

8-Port I/O Expander with LED Intensity

Control and Interrupt

______________________________________________________________________________________ 25

Package Information (continued)

(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages

- A -

0.10

D/2

E/2

- B -

0.08

(NE - 1) X e

D2/2

0.10 M C A B

(ND - 1) X e

E2/2

12x16L QFN THIN.EPS

PROPRIETARY INFORMATION

TITLE:

PACKAGE OUTLINE 12 & 16L, QFN THIN, 3x3x0.8 mm

21-0136

REV.DOCUMENT CONTROL NO.APPROVAL

MAX7315

8-Port I/O Expander with LED Intensity Control and Interrupt

26 ______________________________________________________________________________________

Package Information (continued)

(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages

EXPOSED PAD VARIATIONS

NOTES:

1. DIMENSIONING & TOLERANCING CONFORM TO ASME Y14.5M-1994.

2. ALL DIMENSIONS ARE IN MILLIMETERS. ANGLES ARE IN DEGREES.

3. N IS THE TOTAL NUMBER OF TERMINALS.

4. THE TERMINAL #1 IDENTIFIER AND TERMINAL NUMBERING CONVENTION SHALL CONFORM TO JESD 95-1 SPP-012. DETAILS OF TERMINAL #1 IDENTIFIER ARE OPTIONAL, BUT MUST BE LOCATED WITHIN THE ZONE INDICATED. THE TERMINAL #1 IDENTIFIER MAY BE EITHER A MOLD OR MARKED FEATURE.

5. DIMENSION b APPLIES TO METALLIZED TERMINAL AND IS MEASURED BETWEEN 0.20 mm AND 0.25 mm FROM TERMINAL TIP.

6. ND AND NE REFER TO THE NUMBER OF TERMINALS ON EACH D AND E SIDE RESPECTIVELY.

7. DEPOPULATION IS POSSIBLE IN A SYMMETRICAL FASHION.

8. COPLANARITY APPLIES TO THE EXPOSED HEAT SINK SLUG AS WELL AS THE TERMINALS.

9. DRAWING CONFORMS TO JEDEC MO220 REVISION C.

PROPRIETARY INFORMATION

TITLE:

PACKAGE OUTLINE 12 & 16L, QFN THIN, 3x3x0.8 mm

APPROVAL

DOCUMENT CONTROL NO.

21-0136

REV.

MAX7315

8-Port I/O Expander with LED Intensity

Control and Interrupt

Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.

Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 27

Package Information (continued)

(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages

TSSOP4.40mm.EPS

Rainbow Electronics MAX7315 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual