Datasheet

LTC2938/LTC2939
6
293839ff
TYPICAL PERFORMANCE CHARACTERISTICS
WDO Pull-Up Current vs V2
WDI Input Threshold
vs Temperature
I
SINK
vs Supply Voltage (RST)
Voltage Output Low
vs Sink Current (RST, WDO)
WDI Input Current vs Temperature
CRT: Reset Timeout Capacitor. Attach an external capaci-
tor (C
RT
) to GND to set a reset timeout of 2ms/nF. A 47nF
capacitor generates a 94ms reset delay time. Leaving CRT
unconnected generates a minimum timeout period of ap-
proximately 20μs which will vary depending on parasitic
capacitance on the pin.
TEMPERATURE (°C)
–50
–20
WDI INPUT CURRENT, I
WDI
(μA)
–15
–5
0
5
20
15
0
50
75
–10
10
–25
25
100
125
29389 G15
V
WDI
= 5V
V
WDI
= 0.7V
V
WDI
= 0V
V
WDI
= 1.1V
TEMPERATURE (°C)
–50
0.50
WDI INPUT THRESHOLD, V
WDI
(V)
0.75
1.50
1.25
0
50
75
1.00
–25
25
100
125
29389 G17
HIGH
LOW
OPEN (MINIMUM)
OPEN (MAXIMUM)
V1 OR V2 (V)
0
I
SINK
(mA)
9
12
15
4
29389 G13
6
3
0
1
2
3
5
T
A
= 25°C
V
OL
= 0.4V
V
OL
= 0.2V
125°C
I
SINK
(mA)
0
V
OL
(mV)
300
400
500
8
29389 G14
200
100
0
2
4
6
10
V1 = 5V
V2 = 3V
85°C
–40°C
25°C
V2 (V)
1
0
PULL-UP CURRENT (μA)
3
6
9
12
15
18
23 45
29389 G16
T
A
= 25°C
WDO = GND
PIN FUNCTIONS
CWT: Watchdog Timeout Capacitor. Attach a capacitor (C
WT
)
between CWT and GND to set a watchdog timeout period
of 20ms/nF. A 47nF capacitor generates a 940ms watchdog
timeout period. Leaving CWT unconnected generates a
minimum timeout period of approximately 200μs which