MAXIM MAX7314 Technical data

19-3170; Rev 4; 4/05

EVALUATION KIT

AVAILABLE

18-Port GPIO with LED Intensity Control,

Interrupt, and Hot-Insertion Protection

General Description

The MAX7314 I2C-compatible serial interfaced peripheral provides microprocessors with 16 I/O ports plus one output-only port and one input-only port. Each I/O port can be individually configured as either an open-drain current-sinking output rated at 50mA and 5.5V, or a logic input with transition detection. The output-only port can be assigned as an interrupt output for transition detection. The outputs are capable of driving LEDs, or providing logic outputs with external resistive pullup up to 5.5V.

Eight-bit PWM current control is built in for all 17 output ports. A 4-bit global control applies to all LED outputs and provides coarse adjustment of current from fully off to fully on with 14 intensity steps in between. Each output has an 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.

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 clock input (up to 1kHz) on BLINK or by a register. The BLINK input can also be used as a logic control to turn the LEDs on and off, or as a general-purpose input.

The MAX7314 supports hot insertion. All port pins, the INT output, SDA, SCL, RST, BLINK, and the slave address input ADO remain high impedance in powerdown (V+ = 0V) with up to 6V asserted upon them.

The MAX7314 is controlled through a 2-wire serial interface, and uses four-level logic to allow four I addresses from only one select pin.

♦ 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 Individual 16-Step Intensity Controls

♦ 2-Phase LED Blinking

♦ 50mA Maximum Port Output Current

♦ Supports Hot Insertion

♦ Outputs are 5.5V-Rated Open Drain

♦ Inputs are Overvoltage Protected to 5.5V

♦ Transition Detection with Interrupt Output

♦ 1.2µA (typ), 3.6µA (max) Operating Current

♦ Small 4mm x 4mm, Thin QFN Package

♦ -40°C to +125°C Temperature Range

Ordering Information

PART TEMP RANGE

MAX7314ATG -40°C to +125°C

MAX7314AEG -40°C to +125°C 24 QSOP —

PINPACKAGE

24 Thin QFN 4mm x 4mm x 0.8mm

Typical Application Circuit

Features

PKG CODE

T2444-4

MAX7314

Applications

LCD Backlights LED Status Indication Relay Drivers Keypad Backlights RGB LED Drivers System I/O Ports

Pin Configurations continued at end of data sheet.

μC

0.047μF

SDA SCL

3.3V

V+

SDA

MAX7314

SCL

I/O

BLINK

I/O

RST

INT

INT/O16

AD0

P0 P1 P2 P3 P4 P5 P6 P7 P8

P9 P10 P11 P12 P13 P14 P15

GND

3.3V 5V

INPUT 1 INPUT 2 INPUT 3 INPUT 4 INPUT 5

OUTPUT

________________________________________________________________ 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.

MAX7314

18-Port GPIO with LED Intensity Control, Interrupt, and Hot-Insertion Protection

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, BLINK, RST, P0–P15 .....................-0.3V to +6V

INT/O16 ...................................................................-0.3V to +8V

DC Current on P0–P15, INT/O16 ........................................55mA

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

Maximum GND Current ....................................................350mA

Continuous Power Dissipation (T

= +70°C)

24-Pin QSOP (derate 9.5mW/°C over +70°C)..............761mW

24-Pin QFN (derate 20.8mW/°C over +70°C) ............1666mW

Operating Temperature Range

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, BLINK, P0–P15

Input Low Voltage SDA, SCL, AD0, BLINK, P0–P15

Input Leakage Current SDA, SCL, AD0, BLINK, P0–P15

Input Capacitance SDA, SCL, AD0, BLINK, P0–P15

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 d i sab l ed

inputs at V+ or GND; PWM

intensity control enabled

inputs at V+ or GND; PWM

intensity control enabled

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

= 400kHz; other digital

SCL

= 400kHz; other digital

SCL

TA = +25°C 1.2 2.3

TA = -40°C to +85°C 2.8

= T

MIN

to T

MAX

TA = +25°C 8.5 15.1

TA = -40°C to +85°C 16.5

TA = +25°C 50 95.3

TA = -40°C to +85°C 99.2

TA = +25°C 57 110.2

TA = -40°C to +85°C 117.4

0 5.5 V

3.6

17.2

102.4

122.1

0.7 x V+

0.3 x V+

8pF

µA

MAX7314

18-Port GPIO with LED Intensity Control,

Interrupt, and Hot-Insertion Protection

_______________________________________________________________________________________ 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)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

V+ = 2V, I

Output Low Voltage P0–P15, INT/O16

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 RST Pulse Width t

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 0.26

TA = -40°C to +85°C 0.3

= T

MIN

to T

MAX

0.32

TA = +25°C 0.13 0.23

TA = -40°C to +85°C 0.26V+ = 2.5V, I

= T

MIN

to T

MAX

0.28

TA = +25°C 0.12 0.23

TA = -40°C to +85°C 0.24

= T

MIN

to T

MAX

0.26

32 kHz

400 kHz

1.3 µs

0.6 µs

180 ns

1.3 µs

0.7 µs

20 +

0.1C

20 +

0.1C

20 +

0.1C

300 ns

250 ns

1µs

MAX7314

18-Port GPIO with LED Intensity Control, Interrupt, and Hot-Insertion Protection

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

MAX7314 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)

MAX7314 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)

MAX7314 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 Set-Up 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

MAX7314

18-Port GPIO with LED Intensity Control,

Interrupt, and Hot-Insertion Protection

_______________________________________________________________________________________ 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

TEMPERATURE (°C)

MAX7314 toc07

2ms/div

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

PORT OUTPUT LOW VOLTAGE WITH 20mA

LOAD CURRENT vs. TEMPERATURE

0.6

ALL OUTPUTS LOADED

(V)

0.5

MAX7314 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 1, 2V/div

OUTPUT 1 INDIVIDUAL INTENSITY SET TO 1/16

OUTPUT 2, 2V/div

OUTPUT 2 INDIVIDUAL INTENSITY SET TO 14/15

V+ = 2V

V+ = 2.7V

TEMPERATURE (°C)

2ms/div

V+ = 3.6V

MAX7314 toc08

1.050

1.025

MAX7314 toc05

1.000

0.975

0.950

PWM CLOCK FREQUENCY (kHz)

0.925

OUTPUT 1 2V/div

OUTPUT 2 2V/div

0.900

(V)

0.35

0.30

0.25

0.20

0.15

0.10

0.05

1109580655035205-10-25

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

0453525155

ONLY ONE OUTPUT LOADED

SINK CURRENT (mA)

MAX7314 toc06

V+ = 2V

1109580655035205-10-25

MAX7314 toc09

V+ = 3.6V

5040302010

MAX7314

Functional Overview

The MAX7314 is a general-purpose input/output (GPIO) peripheral that provides 16 I/O ports, P0–P15, controlled through an I2C-compatible serial interface. A 17th output-only port, INT/O16, 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 MAX7314’s supply voltage. The MAX7314 is rated for a ground current of 350mA, allowing all 17 outputs to sink 20mA at the same time. Figure 1 shows the output structure of the MAX7314. The ports default to inputs on power-up.

18-Port GPIO with LED Intensity Control, Interrupt, and Hot-Insertion Protection

6 _______________________________________________________________________________________

Pin Description

Figure 1. Simplified Schematic of I/O Ports

QSOP QFN

122INT/O16

223RST

3 24 AD0

4–11, 13–20 1–8, 10–17 P0–P15 Input/Output Ports. P0–P15 are open-drain I/Os rated at 5.5V, 50mA.

12 9 GND Ground. Do not sink more than 350mA into the GND pin.

21 18 BLINK Input Port Configurable as Blink Control or General-Purpose Input

22 19 SCL I2C-Compatible Serial Clock Input

23 20 SDA I2C-Compatible Serial Data I/O

24 21 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

Output Port. Open-drain output rated at 7V, 50mA. Configurable as interrupt output or general-purpose output.

Reset Input. Active low clears the 2-wire interface and puts the device in the same condition as power-up reset.

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

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

Port Inputs and Transition Detection

Input ports registers reflect the incoming logic levels of the port pins, regardless of whether the pin is defined as an input or an output. Reading an input 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 an 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/O16 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 appropriate input ports register is read.

The INT/O16 pin can be configured as either an interrupt output or as a 17th output port with the same static or blink controls as the other 16 ports (Table 4).

Port Output Control and LED Blinking

The two blink phase 0 registers set the output logic levels of the 16 ports P0–P15 (Table 8). These registers control the port outputs if the blink function is disabled. A duplicate pair of registers, the blink phase 1 registers, are 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 registers and the blink phase 1 registers using hardware control (the BLINK input) and/or software control (the blink flip flag in the configuration register) (Table 4). The logic level of the BLINK input can be read back through the blink status bit in the configuration register (Table 4). The BLINK input, therefore, can be used as a general-purpose logic input (GPI port) if the blink function is not required.

PWM Intensity Control

The MAX7314 includes an internal oscillator, nominally 32kHz, to generate PWM timing for LED intensity control. PWM intensity control can be enabled on an output-byoutput basis, allowing the MAX7314 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 MAX7314 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 MAX7314 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 MAX7314, like all I2C slaves, has to monitor every transmission.

MAX7314

18-Port GPIO with LED Intensity Control,

Interrupt, and Hot-Insertion Protection

_______________________________________________________________________________________ 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

MAX7314

Serial Interface

Serial Addressing

The MAX7314 operates as a slave that sends and receives data through an I

C-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 MAX7314 and generates the SCL clock that synchronizes the data transfer (Figure 2).

The MAX7314 SDA line operates as both an input and an open-drain output. A pullup resistor, typically 4.7kΩ, is required on the SDA. The MAX7314 SCL line operates only as an input. A pullup resistor, typically 4.7kΩ, is required on SCL if there are multiple masters on the 2-wire 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 MAX7314 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 MAX7314, the device generates the acknowledge bit because the MAX7314 is the recipient. When the MAX7314 is transmitting to the master, the master generates the acknowledge bit because the master is the recipient.

Slave Address

The MAX7314 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.

18-Port GPIO with LED Intensity Control, Interrupt, and Hot-Insertion Protection

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

12 89

CHANGE OF DATA

ALLOWED

CLOCK PULSE

FOR ACKNOWLEDGE

STOP

CONDITION

SDA

MSB

SCL

LSB

ACK00A6 0 0A2 R/W

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