Datasheet
LTC690/LTC691
LTC694/LTC695
4
690ff
For more information www.linear.com/690
elecTrical characTerisTics
PARAMETER CONDITIONS MIN TYP MAX UNITS
Battery Back-Up Switching
Operating Voltage Range V
CC
V
BATT
4.75
2.00
5.50
4.25
V
V
V
OUT
Output Voltage I
OUT
= 1mA
l
V
CC
– 0.05
V
CC
– 0.10
V
CC
– 0.005
V
CC
– 0.005
V
V
I
OUT
= 50mA V
CC
– 0.50 V
CC
– 0.250 V
V
OUT
in Battery Back-Up Mode I
OUT
= 250µA, V
CC
< V
BATT
V
BATT
– 0.1 V
BATT
– 0.2 V
Supply Current (Exclude I
OUT
) I
OUT
= 50mA
l
0.6
0.6
1.5
2.5
mA
mA
Supply Current in Battery Back-Up Mode V
CC
= 0V, V
BATT
= 2.8V
l
0.04
0.04
1
5
µA
µA
Battery Standby Current (+ = Discharge, – = Charge) 5.5 > V
CC
> V
BATT
+ 0.2V
l
–0.1
–0.1
+0.02
+0.10
µA
µA
Battery Switchover Threshold, V
CC
– V
BATT
Power Up
Power Down
70
50
mV
mV
Battery Switchover Hysteresis 20 mV
BATT ON Output Voltage (Note 4) I
SINK
= 3.2mA 0.4 V
BATT ON Output Short-Circuit Current (Note 4) BATT ON = V
OUT
Sink Current 35 m
BATT ON = 0V Source Current 0.5 1 25 µA
Reset and Watchdog Timer
Reset Voltage Threshold
l
4.5 4.65 4.75 V
Reset Threshold Hysteresis 40 mV
Reset Active Time (LTC690/91) (Note 5) OSC SEL HIGH, V
CC
= 5V
l
40
35
50
50
60
70
ms
ms
Reset Active Time (LTC694/95) (Note 5) OSC SEL HIGH, V
CC
= 5V
l
160
140
200
200
240
280
ms
ms
Watchdog Timeout Period, Internal Oscillator Long Period, V
CC
= 5V
l
1.2
1
1.6
1.6
2.00
2.25
sec
sec
Short Period, V
CC
= 5V
l
80
70
100
100
120
140
ms
ms
Watchdog Timeout Period, External Clock (Note 6) Long Period
Short Period
4032
960
4097
1025
Clock
Cycles
Reset Active Time PSRR 1 ms/V
Watchdog Timeout Period PSRR, Internal OSC 1 ms/V
Minimum WDI Input Pulse Width V
IL
= 0.4V, V
IH
= 3.5V
l
200 ns
RESET Output Voltage at V
CC
= 1V I
SINK
= 10µA, V
CC
= 1V 4 200 mV
RESET and LOWLINE Output Voltage (Note 4) I
SINK
= 1.6mA, V
CC
= 4.25V
I
SOURCE
= 1µA, V
CC
= 5V
3.5
0.4 V
V
RESET and WDO Output Voltage (Note 4) I
SINK
= 1.6mA, V
CC
= 5V
I
SOURCE
= 1µA, V
CC
= 4.25V
3.5
0.4 V
V
The l denotes specifications which apply over the operating temperature
range, otherwise specifications are at T
A
= 25°C. V
CC
= full operating range, V
BATT
= 2.8V, unless otherwise noted.