Datasheet

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SLVS213C − MAY 1999 − REVISED AUGUST 2008
14
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
detailed description (continued)
push-pull operating mode
In push-pull operating mode (COM = low), the two single-ended charge pumps operate with 180° phase shift.
The oscillator signal has a 50% duty cycle. Each single-ended charge pump transfers charge into its transfer
capacitor (C
xF
) in one-half of the period. During the other half of the period (transfer phase), C
xF
is placed in
series with the input to transfer its charge to C
O
. While one single-ended charge pump is in the charge phase,
the other one is in the transfer phase. This operation guarantees an almost constant output current which
ensures a low output ripple. COM is a logic input and should not remain floating. The typical operating circuit
of the TPS60100 in push-pull mode is shown in Figure 1 and Figure 30.
single-ended operating mode
When COM is high, the device runs in single-ended operating mode. The two single-ended charge pumps
operate in parallel without phase shift. They transfer charge into the transfer capacitor (C
F
) in one half of the
period. During the other half of the period (transfer phase), C
F
is placed in series with the input to transfer its
charge to C
O
. In single-ended operating mode only one transfer capacitor (C
F
= C
1F
+ C
2F
) is required, resulting
in less board space.
IN
IN
C1+
C1−
ENABLE
OUT
OUT
FB
C2+
C2−
SYNC
SKIP COM 3V8
PGND GND
INPUT
1.8 V to 3.6 V
C
IN
10 µF
OUTPUT
3.3 V 200 mA
C
O
= 22 µF
C
F
= 4.7 µF
+
OFF/ON
TPS60100
+
Figure 31. Typical Operating Circuit TPS60100 in Single-Ended Operating Mode
Table 2. Tradeoffs Between Operating Modes
FEATURE PUSH-PULL MODE
(COM = Low)
SINGLE-ENDED MODE
(COM = High)
Output ripple amplitude Small amplitude Large amplitude
Smallest board space X
regulated 3.3 V operating mode
In regulated 3.3 V operating mode (3V8 = low) the device provides a regulated 3.3-V output from a1.8-V to 3.6-V
input. 3V8 is a logic input and should not remain floating. The typical operating circuit of the TPS60100 in (3.3
V) regulated mode is shown in Figure 1 and Figure 30.
pre-regulated 3.8 V operating mode
When 3V8 is high, the device provides a preregulated 3.8-V output from a 2.2-V to 3.6-V input. This mode should
be used if a tighter output voltage tolerance is a major concern. In this case the charge pump generates the input
voltage for a low-dropout regulator.