Datasheet

Protection
Shutdown Mode
Capacitor Selection
V
IN
Enable
V
OUT
GND
REG710
C
IN
2.2mF
C
OUT
2.2mF
C
PUMP
0.22mF
4 6
3
5
1
2
REG71055-Q1
www.ti.com ....................................................................................................................................................................................................... SBAS477 – JULY 2009
The regulator has thermal shutdown circuitry that protects it from damage caused by overload conditions. The
thermal protection circuitry disables the output when the junction temperature reaches approximately 160 ° C,
allowing the device to cool. When the junction temperature cools to approximately 140 ° C, the output circuitry is
automatically reenabled. Continuously running the regulator into thermal shutdown can degrade reliability. The
regulator also provides current limit to protect itself and the load.
The EN pin enables the IC when pulled high and places it into energy-saving shutdown mode when pulled low.
When in shutdown mode, the output is disconnected from the input and the quiescent current is reduced to 0.01
µ A typical. This shutdown mode functionality is only valid when V
IN
is above the minimum recommended
operating voltage. The EN pin cannot be left floating and must be actively terminated either high or low.
For minimum output voltage ripple, the output capacitor C
OUT
should be a ceramic, surface-mount type. Tantalum
capacitors generally have a higher effective series resistance (ESR) and may contribute to higher output voltage
ripple. Leaded capacitors also increase ripple due to the higher inductance of the package itself. To achieve best
operation with low input voltage and high load current, the input and pump capacitors (C
IN
and C
PUMP
,
respectively) should also be surface-mount ceramic types. In all cases, X7R or X5R dielectric are recommended.
See the typical operating circuit shown in Figure 10 for component values.
Figure 10. Typical Operating Circuit
With light loads or higher input voltage, a smaller 0.1 µ F pump capacitor (C
PUMP
) and smaller 1 µ F input and
output capacitors (C
IN
and C
OUT
, respectively) can be used. To minimize output voltage ripple, increase the
output capacitor, C
OUT
, to 10 µ F or larger.
The capacitors listed in Table 1 can be used with the REG71055. This table is only a representative list of
compatible parts.
Table 1. Suggested Capacitors
RATED
DIELECTRIC PACKAGE WORKING
MANUFACTURER PART NUMBER VALUE TOLERANCE MATERIAL SIZE VOLTAGE
C1206C255K8RAC 2.2 µ F ± 10% X7R 1206 10 V
Kemet
C1206C224K8RAC 0.22 µ F ± 10% X7R 1206 10 V
ECJ − 2YBOJ225K 2.2 µ F ± 10% X5R 805 6.3 V
Panasonic ECJ − 2VBIC224K 0.22 µ F ± 10% X7R 805 16 V
ECJ − 2VBIC104 0.1 µ F ± 10% X7R 805 16 V
EMK316BJ225KL 2.2 µ F ± 10% X7R 1206 16 V
Taiyo Yuden
TKM316BJ224KF 0.22 µ F ± 10% X7R 1206 25 V
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Product Folder Link(s): REG71055-Q1