Datasheet

4
LTC1515 Series
TYPICAL PERFORMANCE CHARACTERISTICS
UW
LTC1515-X Shutdown Supply
Current vs Input Voltage
LTC1515-X Step-Down Mode
5V Load Transient Response
INPUT VOLTAGE (V)
0
POSITIVE SUPPLY CURRENT (µA)
25
20
15
10
5
0
8
1515 G12
2
4
6
10
85°C
SHDN = 0V
–40°C
25°C
V
OUT
AC COUPLED
100mV/DIV
I
OUT
50mA/DIV
V
IN
= 8V, V
OUT
= 5V, C
OUT
= 10µF, T
A
= 25°C
1515 G10
50mA
0mA
V
OUT
AC COUPLED
100mV/DIV
I
OUT
50mA/DIV
LTC1515-X Step-Up Mode
5V Load Transient Response
V
IN
= 3.3V, V
OUT
= 5V, C
OUT
= 10µF, T
A
= 25°C
1515 G11
low will force V
OUT
to 3V (LTC1515-3/5) or 3.3V (LTC1515-
3.3/5). As with the SHDN pin, the 5/3 pin may be driven with
3V logic over the entire V
IN
range. The 5/3 pin may not float.
FB (LTC1515) (Pin 3): Feedback Input. The voltage on this
pin is compared to the internal reference voltage (1.232V)
to keep the output in regulation. An external resistor divider
is required between V
OUT
and FB to adjust the output
voltage. Total divider resistance should not exceed 2M.
GND (Pin 4): Ground. Should be tied to a ground plane for
best performance.
C1
–
(Pin 5): Charge Pump Flying Capacitor, Negative
Terminal.
SHDN (Pin 1): Shutdown Input. A logic low on the SHDN
pin puts the part into shutdown mode. A logic high (V
SHDN
≥ 1.6V) enables the part. At high V
IN
voltages, the SHDN
pin may still be controlled with 3V logic without causing a
large rise in V
IN
quiescent current. The SHDN pin may not
float; connect to V
IN
if unused.
POR (Pin 2): Open-Drain Power-On Reset Output. This pin
will pull low upon initial power-up, during shutdown or
until V
OUT
has been within 6.5% of its regulated value for
more than 200ms typ.
5/3 (LTC1515-X) (Pin 3): Output Voltage Select. A logic
high on the 5/3 pin will force V
OUT
to regulate to 5V. A logic
PIN FUNCTIONS
UUU
INPUT VOLTAGE (V)
0
EFFICIENCY (%)
100
80
60
40
20
8
1515 G09
2
4
6
10
V
OUT
= 3V
I
OUT
= 10mA
T
A
= 25°C
LTC1515-X
3V Efficiency vs Input Voltage
LTC1515-X
5V Efficiency vs Input Voltage
INPUT VOLTAGE (V)
2
EFFICIENCY (%)
100
80
60
40
20
10
1515 G08
4
6
8
12
V
OUT
= 5V
I
OUT
= 10mA
TA = 25°C
INPUT VOLTAGE (V)
0
EFFICIENCY (%)
100
80
60
40
20
8
1515 G07
2
4
6
10
V
OUT
= 3.3V
I
OUT
= 10mA
TA = 25°C
LTC1515-X
3.3V Efficiency vs Input Voltage