19-1259; Rev 2; 1/09
SPI/Microwire-Compatible
UART in QSOP-16
General Description
The MAX3100 universal asynchronous receiver transmit-
ter (UART) is the first UART specifically optimized for
small microcontroller-based systems. Using an
SPI™/Microwire™ interface for communication with the
host microcontroller (µC), the MAX3100 comes in a com-
pact 16-pin QSOP. The asynchronous I/O is suitable for
use in RS-232, RS-485, IR, and opto-isolated data links.
IR-link communication is easy with the MAX3100’s
infrared data association (IrDA) timing mode.
The MAX3100 includes a crystal oscillator and a baud-
rate generator with software-programmable divider ratios
for all common baud rates from 300 baud to 230k baud.
A software- or hardware-invoked shutdown lowers quies-
cent current to 10µA, while allowing the MAX3100 to
detect receiver activity.
An 8-word-deep first-in/first-out (FIFO) buffer minimizes
processor overhead. This device also includes a flexible
interrupt with four maskable sources, including address
recognition on 9-bit networks. Two hardware-handshak-
ing control lines are included (one input and one output).
The MAX3100 is available in 14-pin plastic DIP and small,
16-pin QSOP packages in the commercial and extended
temperature ranges.
____________________________Features
o
Small TQFN and QSOP Packages Available
o
Full-Featured UART:
—IrDA SIR Timing Compatible
—8-Word FIFO Minimizes Processor
Overhead at High Data Rates
—Up to 230k Baud with a 3.6864MHz Crystal
—9-Bit Address-Recognition Interrupt
—Receive Activity Interrupt in Shutdown
o
SPI/Microwire-Compatible µC Interface
o
Lowest Power:
—150µA Operating Current at 3.3V
—10µA in Shutdown with Receive Interrupt
o
+2.7V to +5.5V Supply Voltage in Operating Mode
o
Schmitt-Trigger Inputs for Opto-Couplers
o
TX and
RTS
Outputs Sink 25mA for Opto-Couplers
MAX3100
Ordering Information
PART
MAX3100CPD+
MAX3100CEE+
MAX3100EPD+
MAX3100EEE+
MAX3100ETG+
TEMP RANGE
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
14 Plastic DIP
16 QSOP
14 Plastic DIP
16 QSOP
24 TQFN-EP*
________________________Applications
Handheld Instruments
Intelligent Instrumentation
UART in SPI Systems
Small Networks in HVAC or Building Control
Isolated RS-232/RS-485: Directly Drives Opto-Couplers
Low-Cost IR Data Links for Computers/Peripherals
TOP VIEW
+
DIN 1
DOUT 2
SCLK 3
CS 4
IRQ 5
SHDN 6
GND 7
+Denotes
a lead(Pb)-free/RoHS-compliant package.
EP = Exposed pad.
Typical Operating Circuit appears at end of data sheet.
Pin Configurations
N.C.
N.C.
14
18
14 V
CC
13 TX
12 RX
N.C. 19
N.C. 20
TX 21
V
CC
22
DIN 23
N.C. 24
17
16
15
13
12 N.C.
11 X1
10 X2
DIN 1
DOUT 2
SCLK 3
CS 4
N.C. 5
IRQ 6
SHDN 7
GND 8
N.C.
RX
RTS
CTS
+
16 V
CC
15 TX
14 RX
MAX3100
11 RTS
10 CTS
9
8
X1
X2
MAX3100
*EP
2
DOUT
3
SCLK
4
CS
5
IRQ
6
N.C.
9
8
GND
SHDN
N.C.
MAX3100
13 RTS
12 N.C.
11 CTS
10 X1
9
X2
+
1
N.C.
7
DIP
TQFN-EP
*EP = EXPOSED PAD, CONNECT EP TO GROUND
QSOP
SPI is a trademark of Motorola, Inc. Microwire is a trademark of National Semiconductor Corp.
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
SPI/Microwire-Compatible
UART in QSOP-16
MAX3100
ABSOLUTE MAXIMUM RATINGS
V
CC
to GND ...........................................................................+6V
Input Voltage to GND
(CS,
SHDN,
X1,
CTS,
RX, DIN, SCLK) ....-0.3V to (V
CC
+ 0.3V)
Output Voltage to GND
(DOUT,
RTS,
TX, X2) ..............................-0.3V to (V
CC
+ 0.3V)
IRQ...........................................................................-0.3V
to 6V
TX,
RTS
Output Current ....................................................100mA
X2, DOUT,
IRQ
Short-Circuit Duration
(to V
CC
or GND) .........................................................Indefinite
Continuous Power Dissipation (T
A
= +70°C)
Plastic DIP (derate 10.00mW/°C above +70°C) .......... 800mW
QSOP (derate 8.30mW/°C above +70°C) .....................667mW
TQFN (derate 33.3mW/°C above +70°C) ................2666.7mW
Operating Temperature Ranges
MAX3100C_ _ ......................................................0°C to +70°C
MAX3100E_ _ ...................................................-40°C to +85°C
Storage Temperature Range ............................ -65°C to +160°C
Lead Temperature (soldering, 10s) ................................ +300°C
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.
ELECTRICAL CHARACTERISTICS
(V
CC
= +2.7V to +5.5V, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are measured at 9600 baud at T
A
= +25°C.)
PARAMETER
Input High Voltage
Input Low Voltage
Input Hysteresis
Input Leakage
Input Capacitance
OSCILLATOR INPUT (X1)
Input High Voltage
Input Low Voltage
Input Current
Input Capacitance
OUTPUTS (DOUT, TX,
RTS)
Output High Voltage
Output Low Voltage
Output Leakage
Output Capacitance
IRQ
OUTPUT (Open Drain)
Output Low Voltage
Output Leakage
Output Capacitance
POWER REQUIREMENTS
V
CC
Supply Current in
Normal Mode
V
CC
Supply Current in
Shutdown
Supply Voltage
2
I
CC
With 1.8432MHz crystal;
all other logic inputs are at
0V or V
CC
SHDN bit = 1 or
SHDN
= 0,
logic inputs are at 0V or V
CC
2.7
V
CC
= 5V
V
CC
= 3.3V
0.27
0.15
1
mA
0.4
10
5.5
µA
V
V
OL
I
LK
C
OUT
I
SINK
= 4mA
V
IRQ
= 5.5V
5
0.4
±1
V
µA
pF
V
OH
V
OL
I
LK
C
OUT
I
SOURCE
= 5mA
I
SOURCE
= 25µA, TX only
TX,
RTS:
I
SINK
= 25mA
DOUT, TX,
RTS:
I
SINK
= 4mA
DOUT only,
CS
= V
CC
5
V
CC
- 0.5
V
CC
- 0.5
0.9
0.4
±1
V
V
µA
pF
V
IH
V
IL
I
IN
C
IN
V
X1
= 0V and 5.5V
V
X1
= 0V and 5.5V
Active mode
Shutdown mode
5
0.7 x V
CC
V
CC
/ 2
V
CC
/ 2
0.2 x V
CC
25
2
V
V
µA
pF
SYMBOL
V
IH
V
IL
V
HYST
I
IL
C
IN
5
V
CC
= 3.3V
0.05 x V
CC
±1
CONDITIONS
MIN
0.7 x V
CC
0.3 x V
CC
TYP
MAX
UNITS
V
V
V
µA
pF
LOGIC INPUTS (DIN, SCLK,
CS, SHDN, CTS,
RX)
I
CC
V
CC
_______________________________________________________________________________________
SPI/Microwire-Compatible
UART in QSOP-16
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +2.7V to +5.5V, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
AC TIMING (Figure 1)
CS
Low to DOUT Valid
CS
High to DOUT Tri-State
CS
to SCLK Setup Time
CS
to SCLK Hold Time
SCLK Fall to DOUT Valid
DIN to SCLK Setup Time
DIN to SCLK Hold Time
SCLK Period
SCLK High Time
SCLK Low Time
SCLK Rising Edge
to
CS
Falling
CS
Rising Edge
to SCLK Rising
CS
High Pulse Width
Output Rise Time
Output Fall Time
t
DV
t
TR
t
CSS
t
CSH
t
DO
t
DS
t
DH
t
CP
t
CH
t
CL
t
CS0
t
CS1
t
CSW
t
r
t
f
TX,
RTS,
DOUT: C
LOAD
= 100pF
TX,
RTS,
DOUT,
IRQ:
C
LOAD
= 100pF
(Note 1)
(Note 1)
C
LOAD
= 100pF
100
0
238
100
100
100
200
200
10
10
C
LOAD
= 100pF
C
LOAD
= 100pF, R
CS
= 10kΩ
100
0
100
100
100
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX3100
Note 1:
t
CS0
and t
CS1
specify the minimum separation between SCLK rising edges used to write to other devices on the SPI bus
and the
CS
used to select the MAX3100. A separation greater than t
CS0
and t
CS1
ensures that the SCLK edge is ignored.
CS
t
CSS
t
CH
•••
t
CSH
•••
t
DS
t
DH
t
CSH
SCLK
t
CL
DIN
t
DV
DOUT
•••
t
DO
•••
t
TR
Figure 1. Detailed Serial-Interface Timing
_______________________________________________________________________________________
3
SPI/Microwire-Compatible
UART in QSOP-16
MAX3100
__________________________________________Typical Operating Characteristics
(T
A
= +25°C, unless otherwise noted.)
SUPPLY CURRENT vs. TEMPERATURE
MAX3100-01
SHUTDOWN CURRENT
vs. TEMPERATURE
1.8432MHz CRYSTAL
9
SHUTDOWN CURRENT (μA)
8
SUPPLY CURRENT (μA)
7
6
5
4
3
2
1
0
V
CC
= 5V
100
0
-40
-20
0
20
40
60
80
100
0
500
400
300
200
MAX3100-02
SUPPLY CURRENT vs.
EXTERNAL CLOCK FREQUENCY
600
V
CC
= 5V
V
CC
= 3.3V
MAX3100-03
1000
900
800
SUPPLY CURRENT (μA)
700
600
500
400
300
200
100
0
-40
-20
0
20
40
60
80
V
CC
= 3.3V
V
CC
= 5V
1.8432MHz CRYSTAL
TRANSMITTING AT
115.2 kbps
10
700
100
1
2
3
4
5
TEMPERATURE (°C)
TEMPERATURE (°C)
EXTERNAL CLOCK FREQUENCY (MHz)
SUPPLY CURRENT vs. BAUD RATE
1.8432 MHz
CRYSTAL
5V
TRANSMITTING
5V
STANDBY
MAX3100-03a
TX, RTS, DOUT OUTPUT CURRENT
vs. OUTPUT LOW VOLTAGE (V
CC
= 3.3V)
MAX3100-04
TX, RTS, DOUT OUTPUT CURRENT
vs. OUTPUT LOW VOLTAGE (V
CC
= 5V)
80
OUTPUT SINK CURRENT (mA)
70
60
50
40
30
20
10
0
DOUT
RTS
TX
MAX3100-05
400
350
SUPPLY CURRENT (μA)
300
250
200
150
100
50
100
1000
10k
BAUD RATE (bps)
100k
3V
TRANSMITTING
3V
STANDBY
70
60
OUTPUT SINK CURRENT (mA)
50
40
30
20
10
0
DOUT
RTS
TX
90
1M
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
VOLTAGE (V)
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
VOLTAGE (V)
4
_______________________________________________________________________________________
SPI/Microwire-Compatible
UART in QSOP-16
Pin Description
PIN
QSOP
1
2
3
4
6
7
8
9
10
11
13
DIP
1
2
3
4
5
6
7
8
9
10
11
TQFN-EP
23
2
3
4
5
8
9
10
11
15
16
NAME
DIN
DOUT
SCLK
CS
IRQ
SHDN
GND
X2
X1
CTS
RTS
FUNCTION
SPI/Microwire Serial-Data Input. Schmitt-trigger input.
SPI/Microwire Serial-Data Output. High impedance when
CS
is high.
SPI/Microwire Serial-Clock Input. Schmitt-trigger input.
Active-Low Chip-Select Input. DOUT goes high impedance when
CS
is high,
IRQ,
TX, and
RTS
are always active. Schmitt-trigger input.
Active-Low Interrupt Output. Open-drain interrupt output to microprocessor.
Hardware-Shutdown Input. When shut down (SHDN = 0), the oscillator turns
off immediately without waiting for the current transmission to end, reducing
supply current to just leakage currents.
Ground
Crystal Connection. Leave X2 unconnected for external clock. See
Crystal-
Oscillator Operation—X1, X2 Connection
section.
Crystal Connection. X1 also serves as an external clock input. See
Crystal-
Oscillator Operation—X1, X2 Connection
section.
General-Purpose Active-Low Input. Read via the
CTS
register bit; often used
for RS-232 clear-to-send input (Table 1).
General-Purpose Active-Low Output. Controlled by the
CTS
register bit. Often
used for RS-232 request-to-send output or RS-485 driver enable.
Asynchronous Serial-Data (receiver) Input. The serial information received
from the modem or RS-232/RS-485 receiver. A transition on RX while in
shutdown generates an interrupt (Table 5).
Asynchronous Serial-Data (transmitter) Output
Positive Supply Pin (2.7V to 5.5V)
No Connection. Not internally connected.
Exposed Pad. Connect EP to ground or leave unconnected.
MAX3100
14
15
16
5, 12
—
12
13
14
—
—
17
21
22
1, 6, 7, 12,
13, 14, 18,
19, 20, 24
—
RX
TX
V
CC
N.C.
EP
Detailed Description
The MAX3100 universal asynchronous receiver transmitter
(UART) interfaces the SPI/Microwire-compatible, synchro-
nous serial data from a microprocessor (µP) to asynchro-
nous, serial-data communication ports (RS-232, RS-485,
IrDA). Figure 2 shows the MAX3100 functional diagram.
The MAX3100 combines a simple UART and a baud-rate
generator with an SPI interface and an interrupt genera-
tor. Configure the UART by writing a 16-bit word to a
write-configuration register, which contains the baud rate,
data-word length, parity enable, and enable of the 8-word
receive first-in/first-out (FIFO). The write configuration
selects between normal UART timing and IrDA timing,
controls shutdown, and contains 4 interrupt mask bits.
Transmit data by writing a 16-bit word to a write-data
register, where the last 7 or 8 bits are actual data to be
transmitted. Also included is the state of the transmitted
parity bit (if enabled). This register controls the state of
the
RTS
output pin. Received words generate an inter-
rupt if the receive-bit interrupt is enabled.
Read data from a 16-bit register that holds the oldest
data from the receive FIFO, the received parity data,
and the logic level at the
CTS
input pin. This register
also contains a bit that is the framing error in normal
operation and a receive-activity indicator in shutdown.
The baud-rate generator determines the rate at which the
transmitter and receiver operate. Bits B0 to B3 in the
write-configuration register determine the baud-rate divi-
sor (BRD), which divides down the X1 oscillator frequen-
cy. The baud clock is 16 times the data rate (baud rate).
The transmitter section accepts SPI/Microwire data, for-
mats it, and transmits it in asynchronous serial format
from the TX output. Data is loaded into the transmit-
buffer register from the SPI/Microwire interface. The
MAX3100 adds start and stop bits to the data and
clocks the data out at the selected baud rate (Table 7).
5
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