Datasheet

 
   
       
SLVS273− FEBRUARY 2000
12
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TYPICAL CHARACTERISTICS
Figure 15
V
I
V
O
− Output Voltage − V
− Input Voltage − V
LINE TRANSIENT RESPONSE
2.0
2.5
5.07
5.05
5.03
3.0
02021816141210468
t − Time − ms
I
O
= 50 mA
t − Time − ms
−1
0
1
2
3
4
5
6
−0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6
OUTPUT VOLTAGE
vs
TIME (START-UP TIMING)
V
I
= 2.4 V
I
O
= 100 mA
−1
0
1
2
3
4
5
6
Out
Enable
Figure 16
V
O
− Output Voltage − V
Enable Voltage − V
APPLICATION INFORMATION
capacitor selection
The TPS6014x requires only four external capacitors as shown in the basic application circuit. Their capacitance
values are closely linked to the output current and output ripple requirements. For lowest ripple, low ESR
(<0.1 Ω) capacitors should be used at the input and output of the charge pump.
The input capacitor improves system efficiency by reducing the input impedance. It also stabilizes the input
current of the power source. The input capacitor should be chosen according to the power supply used and the
distance from the power source to the converter IC. The input capacitor selection also depends on the output
ripple requirements. C
i
is recommended to be about two to four times as large as the flying capacitors. The lower
the ESR of the input capacitor C
i,
the lower is the output ripple.
The output capacitor C
o
can be selected from 2-times to 50-times larger than the flying capacitor, depending
on the ripple tolerance. The larger C
o
and the lower its ESR, the lower will be the output voltage ripple.
Generally, the flying capacitors will be the smallest. Only ceramic capacitors are recommended because of their
low ESR and because they retain their capacitance at the switching frequency. Please be aware that, depending
on the material used to manufacture them, ceramic capacitors might lose their capacitance over temperature
and voltage. Ceramic capacitors of type X7R or X5R material will keep their capacitance over temperature and
voltage, whereas Z5U or Y5V-type capacitors will decrease in capacitance. Table 2 lists recommended
capacitor values.