Datasheet
5
LTC1754-3.3/LTC1754-5
V
OUT
(Pin 1): Regulated Output Voltage. For best perfor-
mance, V
OUT
should be bypassed with a 6.8µF (min) low
ESR capacitor as close as possible to the pin.
GND (Pin 2): Ground. Should be tied to a ground plane for
best performance.
SHDN (Pin 3): Active Low Shutdown Input. A low on
SHDN disables the LTC1754. SHDN must not be allowed
to float.
C
–
(Pin 4): Flying Capacitor Negative Terminal.
V
IN
(Pin 5): Input Supply Voltage. V
IN
should be bypassed
with a 6.8µF (min) low ESR capacitor.
C
+
(Pin 6): Flying Capacitor Positive Terminal.
SI PLIFIED
W
BLOCK DIAGRA
W
TYPICAL PERFOR A CE CHARACTERISTICS
UW
LTC1754-3.3. LTC1754-5, T
A
= 25°C unless otherwise noted.
Oscillator Frequency
vs Supply VoltageEfficiency vs Supply Voltage
SUPPLY VOLTAGE (V)
2.0
70
80
100
3.5 4.5
1754 G19
60
50
2.5 3.0
4.0 5.0 5.5
40
30
90
EFFICIENCY (%)
T
A
= 25°C
C
FLY
= 1µF
LTC1754-5
I
OUT
= 25mA
LTC1754-3.3
I
OUT
= 20mA
SUPPLY VOLTAGE (V)
2.0
OSCILLATOR FREQUENCY (kHz)
800
3.5
1754 G20
650
550
2.5 3.0 4.0
500
450
850
750
700
600
4.5 5.0 5.5
T
A
= 85°C
T
A
= 25°C
T
A
= –40°C
SUPPLY VOLTAGE (V)
2.0
THRESHOLD VOLTAGE (V)
0.85
0.90
0.95
3.5 4.5
1754 G21
0.80
0.75
2.5 3.0
4.0 5.0 5.5
0.70
0.65
T
A
= –40°C
T
A
= 25°C
T
A
= 85°C
–
+
COMP1
2
*
C
+
C
FLY
1µF
C
–
*CHARGE PUMP SHOWN IN PHASE 1, THE CHARGING PHASE.
PHASE 1 IS ALSO THE SHUTDOWN PHASE
1
1
2
CONTROL
V
REF
C
OUT
10µF
C
IN
10µF
V
IN
1754 BD
V
OUT
SHDN
V
SHDN
Threshold Voltage
vs Supply Voltage
UU
U
PI FU CTIO S