Datasheet

5
LT1248
CCHARA TERIST
ICS
UW
AT
Y
P
I
CA
LPER
F
O
R
C
E
GTDR Rise and Fall Time
M
OUT
VOLTAGE (V)
M
OUT
CURRENT (mA)
1.5
1.0
0.5
0
–0.5
–1.0
–1.5
–2.0
–2.5
–3.0
–3.5
–4.0
1248 G15
2.4
1.2
0
–1.2
–2.4
T
J
= 125°C
T
J
= 25°C
T
J
= –55°C
Startup Supply Current vs
Supply Voltage
SUPPLY VOLTAGE (V)
0
SUPPLY CURRENT (µA)
550
500
450
400
350
300
250
200
150
100
50
0
1248 G09
20
125°C
–55°C
25°C
4
81216
2610
14 18
Frequency vs R
SET
and C
SET
Shutdown Mode Supply Current
and Reference Voltage
Synchronization and Shutdown
Thresholds at EN/SYNC Pin
C
SET
CAPACITANCE (pF)
200
FREQUENCY (kHz)
500
450
400
350
300
250
200
150
100
50
0
1248 G10
1400
2200
600 1000 1800
R
SET
= 10k
R
SET
= 15k
R
SET
= 20k
R
SET
= 30k

C
SET
CAPACITANCE (pF)
200
MAXIMUM DUTY CYCLE
1.00
0.99
0.98
0.97
0.96
0.95
0.94
0.93
0.92
0.91
0.90
1248 G11
1400
2200
600 1000 1800
R
SET
= 10k
R
SET
= 15k
R
SET
= 20k
R
SET
= 30k

EN/SYNC VOLTAGE (V)
0
EN/SYNC CURRENT (µA)
–44
–40
–36
–32
–28
–24
–20
–16
–12
–8
–4
0
1248 G13
10
5
T
J
= 125°C
123
4
6789
T
J
= 25°C
T
J
= –55°C
SHUTDOWN
THRESHOLD
SYNCHRONIZATION
THRESHOLD
SS VOLTAGE (V)
0
SS CURRENT (µA)
–22
–20
–18
–16
–14
–12
–10
–8
–6
–4
–2
0

1248 G14
T
J
= 25°C
T
J
= 125°C
T
J
= –55°C
4
8
M
OUT
Pin CharacteristicsSS Pin Characteristics
GTDR Maximum Duty Cycle vs
R
SET
and C
SET
LOAD CAPACITANCE (nF)
0
TIME (ns)
400
300
200
100
0
10
20 30 40
1248 G08
50
RISE TIME
NOTE: GTDR SLEWS
BETWEEN 1V AND 16V
FALL TIME
SUPPLY VOLTAGE (V)
0
SUPPLY CURRENT (mA)
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
1248 G12
32
16
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
REFERENCE VOLTAGE (V)
EN/SYNC ≤ 1.8V
REFERENCE VOLTAGE
T
J
≤ 125°C
T
J
= 125°C
–55°C ≤ T
J
≤ 25°C
SUPPLY CURRENT