Microchip Technology TC3405VQR, TC3405VPE Datasheet

TC3405

T

16-Bit, Low Cost, Low Power Sigma-Delta A/D Converter

Features

• 16-bit Resolution at Eight Conversions Per
Second, Adjustable Down to 10-bit Resolution at
512 Conversions Per Second

• 1.8V – 5.5V Operation, Low Power Operating
250µA; Sleep: 35µA

• microPort™ Serial Bus Requires only two
Interface Lines

• Uses Internal or External Reference

• Automatically Enters Sleep Mode when not in use

• One Differential and Three Single-ended Inputs
with Built-In Multiplexer

•V

Monitor and Reset Generator Operational in

DD

Shutdown Mode

Applications

• Consumer Electronics, Thermostats, CO
Monitors, Humidity Meters, Security Sensors

• Embedded Systems, Data Loggers,
Portable Equipment

• Medical Instruments

Device Selection Table

Part

Number

TC3405VPE 16-PinPDIP(Narrow) 0°Cto+85°C
TC3405VQR 16-PinQSOPNar row) 0°Cto+85°C

Package

Temperature

Range

Package Type

16-Pin PDIP

16-Pin QSOP

IN1+

V

REF

GND

1

215

IN1-

314

IN2

IN3

IN4

TH

IN

TC3405

413

512

611

710

89

16

V

DD

SCLK

A0

A1

RESET

ENABLE

SDAT

REF

OU

General Description

The TC3405 is a l ow cost, low power analog-to-digital
converter based on Microchip’s Sigma-Delta technol­ogy. I t will per form 16-bit conversions (15-bit pl us sign)
at up to eight per second. The TC3405 is optimized for
use as a microcontroller peripheral in low cost, battery
operated systems. A voltage reference is included, or
an external referencecan be used. A V
a resetgeneratorprovidesPower-on Reset and Brown­out protection while an extra threshold detector is suit­able for use as an early warning power fail detector,or
as a Wake-up Timer.

The TC3405’s 2-wire microPort™ digital interface is
used for starting conversions and for reading out the
data. Driving the SCLK line l ow starts a conversion.
Afterthe conversion starts, each additional falling edge
(up to six) detected on SCLK for t
the A/D resolution by one bit and cuts conversion time
in half. After a conversion is completed, clocking the
SCLK line puts the MSB t hrough LSB of the resulting
dataword onto the SDATline,much like a shift register.
The part automatically sleeps when not performing a
data conversion.

TheTC3405isavailableina16-PinPDIPanda16-Pin
QSOP package.

monitor with

DD

seconds reduces

4



2002 Microchip TechnologyInc. DS21414B-page 1

TC3405

Typical Application

V

BATT

+

Input 1

–

+

Input 2

+

Input 3

Input 4 +

V

BATT

130kΩ

110kΩ

C1

0.1µF

Functional Block Diagram

IN1+

IN1-

IN2

IN3

IN4

A0

R1

R2

±10%

+

–

+

–

+

–

+

–

R3

390

IN1+
IN1-

IN2+
IN3+

IN4+

V

TH

REF

REF

1 of 4

AMux

SET

DQ

CLR

V

DD

ENABLE

TC3405

RESET

IN

OUT

TC3405

Start

Conv.

SDAT

SCLK

AO

AI

V

BATT

R6

100k

V

DD

Σ – ∆

Modulator

CONV done

CONVCLK

Clock Generator

and Control

Circuitry

1.193V

Data
Shift
Reg.

CLKOUT

x2

I/01
I/02

I/03
I/04

RST

V

CC

µ

Controller

REF

OUT

REF

IN

SDAT

SCLK

ENABLE

DS21414B-page 2

SET

A1

V

TH

–

+

1.23V

DQ

CLR

Reset Delay Timer

GND

RESET



2002 Microchip TechnologyInc.

TC3405

1.0 ELECTRICAL

CHARACTERISTICS

*Stresses above 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 above those indicated in the

Absolute Maximum Ratings*

Supply Voltage .....................................................6.0V

operation sections of the specifications is not implied.
Exposure to Absolute Maximum Rating conditions for
extended periods may affectdevice reliability.

Voltage on Pin:

RESET

................................ (GND – 0.3V) to 5.5V

Input Voltage (All Other Pins):

................................. (GND – 0.3V) to (V

DD

+0.3V)

Operating Temperature Range ................. 0°C to 85°C

Storage Temperature ........................ -65°C to +150°C

TC3405 DC ELECTRICAL SPECIFICATIONS

Electrical Characteristics: TA= 25°C and VDD= 2.7V, unless otherwise specified. Boldface type specifications apply for

temperaturesof 0°C to 85°C. V

Symbol Parameter Min Typ Max Unit Test Conditions

Power Supply

V

DD

I

DD

I

DDSLEEP

Supply Voltage 1.8 — 5.5 V
SupplyCurrent, DuringDataConversion — 250 — µA
Supply Current, Sleep Mode — 35 80 µATA=+25°C

Accuracy (Dif fere ntial Inputs)

RES Resolution — 16 — Bits
INL IntegralNon-Linearity — .0038 — %FSR V
V

OS

V

NOISE

Offset Error — — ±0.9 %FSR IN+, IN- = 0V

Referred to input — 60 — µVrms
CMR Common Mode Rejection — 75 — dB At DC
FSE Full Scale Error — 0.4% — %FS
PSRR Power SupplyRejection Ratio — 75 — dB V

INn+, INn-, INn

± Differential Input Voltage — — V

V

IN

Absolute Voltage RangeonINn+, INn-, INn GND — V

Input Bias Current — 1 100 nA
C

IN

R

IN

REF

V

REF

I

REF

V

REFOUT

REF
REF

Input Sampling Capacitance — 2 — pF

Differential Input Resistance — 2.0 — MΩ Note 2

REF

IN,

OUT

REFINVoltage Range 0 — 1.25 V

REFINInput Current — 1 — µA

SINK
SRC

REF

REF

REF

Voltage 1.175 1.193 — V

OUT

Current Sink Capability — 10 — µA

OUT

Current Source Capability 300 — — µA

OUT

Note 1: Differential input voltage defined as (V

2: Resistance from INn+ to INn- or INn to GND.
3: @V

=1.8V,I

DD

= 1.25V, Internal Clock Frequency = 520kHz.

REF

+–VIN-).

IN

≤ 200µA.

SOURCE

— 38 50

DD
DD

µA

DD

DD

V Note 1
V

=2.7V

=2.5Vto3.5V



2002 Microchip TechnologyInc. DS21414B-page 3

TC3405

TC3405 DC ELECTRICAL SPECIFICATIONS (CONTINUED)

Electrical Characteristics: TA= 25°C and VDD= 2.7V, unless otherwise specified. Boldface type specifications apply for

temperaturesof 0°C to 85°C. V

Symbol Parameter Min Typ Max Unit Test Conditions

SCLK, A0 A1, ENABLE

V

IL

V

IH

I

LEAK

Input Low Voltage — — 0.3 x

Input High Voltage 0.7xV
Leakage Current — 1 — µA

SDAT, RESET

V

OL

V

OH

V

DDMIN

V

TH

V

CCPFI

V

THR

,PFI

OutputLow Voltage — — 0.4 V IOL=1.5mA
OutputHighVoltage (SDAT) 0.9 x V
MinimumVDDfor PFO, RESET Valid — 1.1 1.3 µA

PFI Input VoltageRange 0 — V

, PFI Input Current -0.1 .01 0.1 µA

V

TH

Threshold (VTH,PFI) — 1.23 — V
Threshold Hysteresis — 30 — mV
Threshold Tempco — 30 — ppm/°C

Note 1: Differential input voltage defined as (V

2: Resistance from INn+ to INn- or INn to GND.
3: @V

=1.8V,I

DD

= 1.25V, Internal Clock Frequency = 520kHz.

REF

+–VIN-).

IN

≤ 200µA.

SOURCE

DD

DD

V

V

DD

——V

——VI

DD

SOURCE

V

=400µA (Note 3 )

TC3405 AC ELECTRICAL SPECIFICATIONS

Electrical Characteristics: T

temperaturesof 0°C to 85°C. V

Symbol Parameter Min Typ Max Unit Test Conditions

t

1

t

2

t

3

Resolution Reduction Clock Width 1 — — µsec Width of SCLK (Negative)
Resolution Reduction Clock Width 1 — — µsec Width of SCLK (Positive)
Conversion Time(15-bit Plus Sign) — 125 — msec 16-bit Conversion, TA=25°C(Note 1)
Conversion Time (14-bit Plus Sign) — t
Conversion Time (13-bit Plus Sign) — t
Conversion Time (12-bit Plus Sign) — t
Conversion Time(11-bit Plus Sign) — t
Conversion Time (10-bit Plus Sign) — t
Conversion Time(9-bitP lus Sign) — t

t

4

t

5

t

6

t

7

t

8

t

9

t

11

Resolution Reduction Window — t3/85.7 — msec Widthof SCLK
SCLK to Data Valid 1000 — — nsec SCLK FallingEdgeto SDAT Valid
Address Setup 0 — — nsec Address Valid to SCLK
Address Hold 1000 — — nsec SCLK to AddressValidHold
Acknowledge Delay — — 1000 nsec SCLKto SDAT Delay
RESET Active Time-out Period — t3*2 — msec Delay from POR or Brown-out

RESET Delay 5 — 64 µsec Delay VTHFalling at 10V/msec to

Note 1: Nominal temperature driftis -2830ppm/C° for temperature less than 25°C and -1340ppm/°C for temperatures

greater than 25°C

= 25°C and VDD= 2.7V, unless otherwise specified. Boldface type specifications apply for

A

= 1.25V, Internal Clock Frequency = 520kHz.

REF

/2.0 — msec 15-bit Conversion

3

/4.0 — msec 14-bit Conversion

3

/7.8 — msec 13-bit Conversion

3

/15.1 — msec 12-bitConversion

3

/28.6 — msec 11-bit Conversion

3

/51.4 — msec 10-bitConversion

3

Recovery to RESET

RESET

Low

=V

.

OH

DS21414B-page 4



2002 Microchip TechnologyInc.

TC3405

2.0 PIN DESCRIPTIONS

ThedescriptionsofthepinsarelistedinTable2-1.

TABLE 2-1: PIN FUNCTION TABLE

Pin No.

(16-Pin PDIP)

(16-Pin QSOP)

1 IN1+ AnalogInput. This is the positive terminalof a true differential input consisting of IN1+ and IN1-.

2 IN1- AnalogInput. This is the negative terminalof a true differential input consisting of IN1+ and IN1-.

3 IN2 Analog Input. This is the positive terminal of a true differential input with the negative input tied

4 IN3 Analog Input. This is the positive terminal of a true differential input with the negative input tied

5 IN4 Analog Input. This is the positive terminal of a true differential input with the negative input tied

6V

7REF

8 GND Ground Terminal.
9REF

10 SDAT Digital Output (push-pull). This is the microPort™ serial data output.S DAT is driven low while the

11 ENABLE Digital Input.Whenthisinput control is pulled low,t he partisinternally restarted.Thatis, any data

12 RESET

13 A1 DigitalInput. Controlsanalogmultiplexerinconjunction withA0 to select one of thefour input

14 A0 DigitalInput. Controlsanalogmultiplexerinconjunction withA1 to select one of thefour input

15 SCLK DigitalInput. This is the microPort™ serial clock input. The TC3405comes out of Sleep mode and a

16 V

Symbol Description

V

= (IN1+ – IN-). See Section 1.0, Electrical Characteristics.

IN1

= (IN+ – IN-) IN1- can swing to, but not below, ground. See Section 1.0, Electrical Characteristics.

V

IN1

internally to GND. See Section 1.0, Electrical Characteristics.

internally to GND. See Section 1.0, Electrical Characteristics.

internally to GND. See Section 1.0, Electrical Characteristics.
AnalogInput. This is the positive input to the internal comparator used to monitor the voltage supply.

TH

The negative input is tied to an internal reference. When V
reset generator drives RESET

AnalogInput. The converter’sreference voltageis the differentialbetween this pin and ground times

IN

two.ItmaybetieddirectlytoREF
reference voltage less than 1.25 may be used in place of REF

AnalogOutput. The internalreferenceconnects to this pin. It may be scaledexternally, and tiedto the

OUT

REF

inputto providetheconverter’s reference voltage.Caremustbe taken in connectingexternal

IN

circuitry to this pin. This pin is in a high impedance state during Sleep mode.

TC3405is converting data, effectively providing a “busy” signal. Afterthe conversion is complete,
every highto low transition on the SCLKpin putsa bit from the resulting data word on theSDAT pin
(from MSB to LSB).

conversion or data read sequence is cleared and the part goes into Sleep mode. When ENABLE
returns high, the part resumes normaloperation.

Digital Output(open drain).This is the outputoftheVDDmonitor reset generator. RESET is driven low
when a Power-on Reset or Brown-out condition is detected.
See Section 1.0, AC Electrical Characteristics.

channels. This address is latched at the falling edgeof the SCLK, which startsan A/D conversion.
A1, A0 = 00 = Input 1; 01 = Input 2; 10 = Input 3; 11 = Input 4.

channels. Thisaddress is latchedatthe fallingedgeofthe SCLK, whichstarts an A/Dconversion.A1,

A0=00=Input1;01=Input2;10=Input3;11=Input4.

conversion cycle begins when this pin is driven low. After the conversion starts, each additional
fallingedge(uptosix) detectedon SCLK for t
the conversion is complete, the data word can be shifted out on the S DAT pin by clocking the SCLK
pin.

Power SupplyInput.

DD

low. See Section 1.0, Electrical Characteristics.

or scaled using a resistor divider. Any user supplied

OUT

seconds, reduces the A/D resolution by one bit. When

4

falls belowtheinternal reference, the

TH

.

OUT



2002 Microchip TechnologyInc. DS21414B-page 5