Linear Technology LTC693IS, LTC693IN, LTC693CS, LTC693CN, LTC692IS8 Datasheet

LTC692/LTC693

Microprocessor

Supervisory Circuits

EATU

F

■

UL Recognized

■

Guaranteed

■

1.5mA Maximum Supply Current

■

Fast (35ns Max.) On-Board Gating of RAM Chip

S

RE

®

®

Reset Assertion at VCC = 1V

Enable Signals

■

SO8 and SO16 Packaging

■

4.40V Precision Voltage Monitor

■

Power OK/Reset Time Delay:
200ms or Adjustable

■

Minimum External Component Count

■

1µA Maximum Standby Current

■

Voltage Monitor for Power Fail or
Low Battery Warning

■

Thermal Limiting

■

Performance Specified Over Temperature

■

Superior Upgrade for MAX690 Family

U

O

PPLICATI

A

■

Critical µP Power Monitoring

■

Intelligent Instruments

■

Battery-Powered Computers and Controllers

■

Automotive Systems

S

DUESCRIPTIO

The LTC692/LTC693 provide complete power supply moni­toring and battery control functions for microprocessor
reset, battery backup, CMOS RAM write protection, power
failure warning and watchdog timing. A precise internal
voltage reference and comparator circuit monitor the
power supply line. When an out-of-tolerance condition
occurs, the reset outputs are forced to active states and the
Chip Enable output unconditionally write-protects exter­nal memory. In addition, the RESET output is guaranteed
to remain logic low even with VCC as low as 1V.

The LTC692/LTC693 power the active CMOS RAMs with a
charge pumped NMOS power switch to achieve low drop­out and low supply current. When primary power is lost,
auxiliary power, connected to the battery input pin, powers
the RAMs in standby through an efficient PMOS switch.

For an early warning of impending power failure, the
LTC692/LTC963 provide an internal comparator with a
user-defined threshold. An internal watchdog timer is
also available, which forces the reset pins to active states
when the watchdog input is not toggled prior to a preset
time-out period.

O

A

PPLICATITYPICAL

≥ 7.5V

V

IN

+

10µF

51k

10k

MICROPROCESSOR RESET, BATTERY BACKUP, POWER FAILURE
WARNING AND WATCHDOG TIMING ARE ALL IN A SINGLE CHIP
FOR MICROPROCESSOR SYSTEMS.

LT1086-5

V

IN

ADJ

5V

V

OUT

+

100µF

U

0.1µF

3V

RESET Output Voltage vs

Supply Voltage

5

TA = 25°C
EXTERNAL PULL-UP = 10µA

= 0V

V

4

BATT

3

2

RESET OUTPUT VOLTAGE (V)

1

0

1

0

2

SUPPLY VOLTAGE (V)

3

4

5

LTC692/3 • TA02

µP

SYSTEM

µP

POWER

LTC692/3 • TA01

0.1µF

POWER TO
CMOS RAM

µP RESET
µP NMI

I/O LINE

100Ω

V

CC

V

BATT

PFI

LTC692
LTC693

GND

V

OUT

RESET

PFO

WDI

0.1µF

1

LTC692/LTC693

A

W

O

LUTEXI T

S

A

WUW

ARB

I

Terminal Voltage

VCC.................................................... –0.3V to 6.0V

V

................................................. –0.3V to 6.0V

BATT

All Other Inputs .................. –0.3V to (V

OUT

Input Current

VCC.............................................................. 200mA

V

............................................................. 50mA

BATT

GND............................................................... 20mA

WU

/

PACKAGE



V

OUT



V

CC

GND

PFI

N8 PACKAGE

8-LEAD PLASTIC DIP

T

JMAX

T

JMAX

S8 Package Conditions: PCB Mount on FR4 Material,

Still Air at 25°C, Copper Trace

O

RDER I FOR ATIO

TOP VIEW

1
2
3
4

= 110°C, θJA = 130°C/W (N)
= 110°C, θJA = 180°C/W (S)

8
7
6
5



S8 PACKAGE

8-LEAD PLASTIC SOIC

V

BATT

RESET
WDI
PFO

ORDER PART

NUMBER



LTC692CN8
LTC692IN8
LTC692CS8
LTC692IS8

S8 PART MARKING

692
692I

U

(Notes 1 and 2)

G

S

+ 0.3V)

V

Output Current .................. Short Circuit Protected

OUT

Power Dissipation............................................. 500mW

Operating Temperature Range

LTC692C/LTC693C ............................... 0°C to 70°C

LTC692I/LTC693I ............................ –40°C to 85°C

Storage Temperature Range ................ –65°C to 150°C

Lead Temperature (Soldering, 10 sec)................. 300°C

U

(Note 3)

TOP VIEW

1

V



BATT

2

V



OUT

3

V



CC

4

GND

BATT ON

LOW LINE

OSC SEL

16-LEAD PLASTIC DIP

S16 Package Conditions: PCB Mount on FR4 Material,

5
6
7

OSC IN

8



N PACKAGE

T

= 110°C, θJA = 130°C/W (N, S)

JMAX

Still Air at 25°C, Copper Trace

16-LEAD PLASTIC SOL

RESET

16

RESET

15

WDO

14

CE IN

13

CE OUT

12

WDI

11

PFO

10

PFI

9



S PACKAGE

ORDER PART

NUMBER

LTC693CN
LTC693IN
LTC693CS
LTC693IS

U

PRODUCT SELECTIO GUIDE

RESET CONDITIONAL

PINS (V) TIMER BACKUP WARNING PROTECT RESET BACKUP
LTC692 8 4.40 X X X
LTC693 16 4.40 X X X X

LTC690 8 4.65 X X X
LTC691 16 4.65 X X X X
LTC694 8 4.65 X X X
LTC695 16 4.65 X X X X
LTC699 8 4.65 X
LTC1232 8 4.37/4.62 X X
LTC1235 16 4.65 X X X X X X
LTC694-3.3 8 2.90 X X X
LTC695-3.3 16 2.90 X X X X

THRESHOLD WATCHDOG BATTERY POWER FAIL RAM WRITE PUSHBUTTON BATTERY

2

LTC692/LTC693

LECTRICAL C CHARA TERIST

E

VCC = Full Operating Range, V

PARAMETER CONDITONS MIN TYP MAX UNITS
Battery Backup Switching

Operating Voltage Range

V

CC

V

BATT

V

Output Voltage I

OUT

V

in Battery Backup Mode I

OUT

Supply Current (Exclude I

Supply Current in Battery Backup Mode VCC = 0V, V

Battery Standby Current 5.5 > VCC > V

(+ = Discharge, – = Charge) ● –1.0 0.10 µA

Battery Switchover Threshold Power Up 70 mV

VCC – V

BATT

Battery Switchover Hysteresis 20 mV
BATT ON Output Voltage (Note 4) I
BATT ON Output Short-Circuit Current (Note 4) BATT ON = V

Reset and Watchdog Timer

Reset Voltage Threshold ● 4.25 4.40 4.50 V
Reset Threshold Hysteresis 40 mV
Reset Active Time OSC SEL HIGH, VCC = 5V 160 200 240 ms

(Note 5)

Watchdog Time-Out Period, Long Period, VCC = 5V 1.2 1.6 2.00 sec

Internal Oscillator

Watchdog Time-Out Period, External Clock Long Period 4032 4097 Clock

(Note 6) Short Period 960 1025 Cycles
Reset Active Time PSRR 1 ms/V
Watchdog Time-Out Period PSRR, Internal OSC 1 ms/V
Minimum WDI Input Pulse Width VIL = 0.4V, VIH = 3.5V ● 200 ns
RESET Output Voltage At VCC = 1V I
RESET and LOW LINE Output Voltage I

(Note 4) I
RESET and WDO Output Voltage I

(Note 4) I

)I

OUT

= 2.8V, TA = 25°C, unless otherwise noted.

BATT

ICS

4.50 5.50 V

2.00 4.00 V

= 1mA V

OUT

I

= 50mA VCC – 0.50 VCC – 0.250 V

OUT

= 250µA, VCC < V

OUT

≤ 50mA 0.6 1.5 mA

OUT

BATT

Power Down 50 mV

= 3.2mA 0.4 V

SINK

BATT ON = 0V Source Current 0.5 1 25 µA

Short Period, VCC = 5V 80 100 120 ms

SINK

SINK
SOURCE

SINK
SOURCE

OUT

= 10µA, VCC = 1V 4 200 mV
= 1.6mA, VCC = 4.25V 0.4 V

= 1µA, VCC = 5V 3.5 V

= 1.6mA, VCC = 5V 0.4 V

= 1µA, VCC = 4.25V 3.5 V

BATT

= 2.8V 0.04 1 µA

+ 0.2V –0.1 0.02 µA

BATT

Sink Current 35 mA

● V

● 0.6 2.5 mA

● 0.04 5 µA

● 140 200 280 ms

● 1.0 1.6 2.25 sec

● 70 100 140 ms

– 0.05 V

CC

– 0.10 VCC – 0.005 V

CC

V

– 0.1 V

BATT

– 0.005 V

CC

– 0.02 V

BATT

3

LTC692/LTC693

LECTRICAL C CHARA TERIST

E

VCC = Full Operating Range, V

PARAMETER CONDITONS MIN TYP MAX UNITS

RESET, RESET, WDO, LOW LINE Output Source Current 1 3 25 µA
Output Short-Circuit Current (Note 4) Output Sink Current 25 mA

WDI Input Threshold Logic Low 0.8 V

WDI Input Current WDI = V

Power Fail Detector

PFI Input Threshold VCC = 5V ● 1.25 1.3 1.35 V
PFI Input Threshold PSRR 0.3 mV/V
PFI Input Current ±0.01 ±25 nA
PFO Output Voltage (Note 4) I

PFO Short Circuit Source Current PFI = HIGH, PFO = 0V 1 3 25 µA

(Note 4) PFI = LOW, PFO = V

PFI Comparator Response Time (falling) ∆VIN = –20mV, VOD = 15mV 2 µs
PFI Comparator Response Time (rising) ∆VIN = 20mV, VOD = 15mV 40 µs

(Note 4) with 10kΩ Pull-Up 8 µs

Chip Enable Gating

CE IN Threshold V

CE IN Pullup Current (Note 7) 3 µA
CE OUT Output Voltage I

CE Propagation Delay VCC = 5V, CL = 20pF 20 35 ns

CE OUT Output Short Circuit Current Output Source Current 30 mA

Oscillator

OSC IN Input Current (Note 7) ±2 µA
OSC SEL Input Pull-Up Current (Note 7) 5 µA
OSC IN Frequency Range OSC SEL = 0V ● 0 250 kHz
OSC IN Frequency with External Capacitor OSC SEL = 0V, C

= 2.8V, TA = 25°C, unless otherwise noted.

BATT

ICS

Logic High 3.5 V

OUT

WDI = 0V

= 3.2mA 0.4 V

SINK

= 1µA 3.5 V

I

SOURCE

OUT

IL

V

IH

= 3.2mA 0.4 V

SINK

= 3.0mA V

I

SOURCE

= 1µA, VCC = 0V V

I

SOURCE

Output Sink Current 35 mA

= 47pF 4 kHz

OSC

● 450µA

● –50 –8 µA

25 mA

0.8 V

2.0 V

– 1.50 V

OUT

– 0.05 V

OUT

● 20 45 ns

The ● denotes specifications which apply over the full operating
temperature range.

Note 1: Absolute maximum ratings are those values beyond which the life
of the device may be impaired.

Note 2: All voltage values are with respect to GND.
Note 3: For military temperature range, consult the factory.
Note 4: The output pins of BATT ON, LOW LINE, PFO, WDO, RESET and

RESET have weak internal pull-ups of typically 3µA. However, external
pull-up resistors may be used when higher speed is required.

4

Note 5: The LTC692/LTC693 have minimum reset active times of 140ms
(200ms typically). The reset active time of the LTC693 can be adjusted
(see Table 2 in Applications Information Section).

Note 6: The external clock feeding into the circuit passes through the
oscillator before clocking the watchdog timer (See BLOCK DIAGRAM).
Variation in the time-out period is caused by phase errors which occur
when the oscillator divides the external clock by 64. The resulting variation
in the time-out period is 64 clocks plus one clock of jitter.

Note 7: The input pins of CE IN, OSC IN and OSC SEL have weak internal
pull-ups which pull to the supply when the input pins are floating.

LPER

TIME (µs)

0

4

5

6

4

LTC692/3 • TPC06

3
2

0

123

5

1

1.305V

1.285V

87

6

VCC = 5V
T

A

= 25°C

+

–

V

PFI

1.3V

PFO

30pF

V

PFI

= 20mV STEP

PFO OUTPUT VOLTAGE (V)

V

vs I

OUT

5.00

4.95

4.90

4.85

OUTPUT VOLTAGE (V)

4.80

OUT

SLOPE = 5Ω

F

O

R

VCC = 5V
V

BATT

= 25°C

T

A

ATYPICA

= 2.8V

UW

CCHARA TERIST

E

C

V

vs I

OUT

2.80

2.78

SLOPE = 125Ω

2.76

OUTPUT VOLTAGE (V)

2.74

OUT

ICS

VCC = 0V
V

BATT

= 25°C

T

A

= 2.8V

LTC692/LTC693

Power Failure Input Threshold
vs Temperature

1.308
VCC = 5V

1.306

1.304

1.302

1.300

1.298

PFI INPUT THRESHOLD (V)

1.296

4.75

232

224

216

208

200

RESET ACTIVE TIME

192

184

–50

10

0

20

LOAD CURRENT (mA)

Reset Active Time vs
Temperature

VCC = 5V

50 100 125

–25 0

25 75

TEMPERATURE (°C)

Power Fail Comparator
Response Time

6

VCC = 5V

5

T

A

4
3
2

1

PFO OUTPUT VOLTAGE (V)

0

1.315V

1.295V

0

30

= 25°C

40

LTC692/3 • TPC01

LTC692/3 • TPC04

V

PFI

40

20

50

V

PFI

1.3V

= 20mV STEP

60

10080

TIME (µs)

2.72
100

0

Reset Voltage Threshold
vs Temperature

4.41

4.40

4.39

4.38

4.37

RESET VOLTAGE THRESHOLD (V)

4.36

4.35

–50

–25 0

+

PFO

140

120

LTC692/3 • TPC07

30pF

180160

–

300

200

LOAD CURRENT (µA)

50 100 125

25 75

TEMPERATURE (°C)

1.315V

1.295V

1.294

400

LTC692/3 • TPC02

500

–50

–25 0

Power Fail Comparator
Response Time

LTC692/3 • TPC05

Power Fail Comparator Response
Time with Pull-Up Resistor

6

VCC = 5V

5

= 25°C

T

A

4
3
2

1

PFO OUTPUT VOLTAGE (V)

0

0

2

V

= 20mV STEP

PFI

4

V

PFI

1.3V

6

TIME (µs)

108

+

PFO

–

12

LTC692/3 • TPC08

25 75

TEMPERATURE (°C)

5V

10k

30pF

14

1816

50 100 125

LTC692/3 • TPC03

5