Datasheet

SYNC
GND PGND
SW
R1
560 kW
R2
300 kW
V
O
= 3.3 V
6.8 Hm
C = 22 F
6.3 V
O
m
VIN
LBI
C = 10 F
25 V
I
m
1 Fm
2
3
4
8
9
7
5
11 12
16
10
6
13
14
15
1
V = 4.3 V to 17 V
I
VIN
EN
VINA
PGNDGND
R5
R6
AGND
TPS62110
SW
LBO
PG
R3
R7
R4
FB
C
ff
10 pF
TPS62110, TPS62111
TPS62112, TPS62113
www.ti.com SLVS585C –JULY 2005–REVISED OCTOBER 2012
When the LBI is used to supervise the battery voltage and shut down the TPS6211x at low-input voltages, the
battery voltage rises when its current drops to zero. The implemented hysteresis on the LBI pin may not be
sufficient for all types of batteries. Figure 19 shows how an additional external hysteresis can be implemented.
See SLVA373 for details.
Figure 19. LBI With Increased Hysteresis
ENABLE/Low-Battery Detector (Enhanced Version) TPS62113 Only
The TPS62113 offers an enhanced LBI functionality to provide a precise, user-programmable undervoltage
shutdown. No additional supply voltage supervisor (SVS) is needed to provide this function. When the enable
(EN) pin is pulled high, only the internal bandgap voltage reference is switched on to provide a reference source
for the LBI comparator. As long as the voltage at LBI is less than the LBI trip point, all other internal circuits are
shut down, reducing the supply current to 10 µA. As soon as input voltage at LBI rises above the LBI trip point of
1.256 V, the device is completely enabled and starts switching.
This functionality is the only difference between the TPS62110 and TPS62113 devices.
NO-LOAD OPERATION
When the converter operates in the forced PWM mode and there is no load connected to the output, the
converter regulates the output voltage by allowing the inductor current to reverse for a short time.
THEORY OF OPERATION / DESIGN PROCEDURE
External Component Selection
The control loop of the TPS6211x family requires a certain value for the output inductor and the output capacitor
for stable operation. As long as the nominal value of L × C ≥ 6.2 µH × 22 µF, the control loop has enough phase
margin and the device is stable. Reducing the inductor value without increasing the output capacitor (or vice
versa) may cause stability problems. There are applications where it may be useful to increase the value of the
output capacitor, and so on, for a low-transient output-voltage change. From a stability point of view, the inductor
value could be decreased to keep the L × C product constant. However, there are drawbacks if the inductor
value is decreased. A low inductor value causes a high inductor ripple current, and therefore reduces the
maximum dc output current. Table 1 gives the advantages and disadvantages when designing the inductor and
output capacitor.
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Product Folder Links: TPS62110 TPS62111 TPS62112 TPS62113