TC1054 TelCom Semiconductor, TC1054 Datasheet - Page 4

• Manufacturer Part Number: TC1054
• Description: 50mA CMOS LDO WITH SHUTDOWN AND ERROR OUTPUT
• Manufacturer: TelCom Semiconductor

PRELIMINARY INFORMATION
TC1054
TC1054-01 6/12/97
DETAILED DESCRIPTION
tor. (If an adjustable version is desired, please see the
TC1070 or TC1071 data sheets.) Unlike the bipolar regula-
tors, the TC1054 supply current does not increase with load
current. In addition, V
tion at very low load currents (an important consideration in
RTC and CMOS RAM battery back-up applications).
tor is enabled any time the shutdown input (SHDN) is at or
above V
below V
or I/O port of a microcontroller. If the SHDN input is not
required, it should be connected directly to the input supply.
While in shutdown, supply current decreases to 0.05 A
(typical) and V
circuited.
ERROR Open Drain Output
lation by more than – 5% (typical). This condition may be
caused by low input voltage, output current limiting, or
thermal limiting. The ERROR threshold is 5% below rated
V
(e.g. ERROR = V
2.85V (typ.) for a 3.0V regulator). ERROR output operation
is shown in Figure 2.
inactive when V
low flag, or as a processor RESET signal (with the addition
of timing capacitor C2). R1 x C2 should be chosen to
maintain ERROR below V
for at least 200msec to allow time for the system to stabilize.
(to CMOS Logic or Tie
OUT
Shutdown Control
to V
The TC1054 is a precision fixed output voltage regula-
Figure 1 shows a typical application circuit. The regula-
ERROR is driven low whenever V
Note that ERROR is active when V
As shown in Figure 1, ERROR can be used as a battery
IN
regardless of the programmed output voltage value
if unused)
IL
IH
BATTERY
. SHDN may be controlled by a CMOS logic gate,
, and shutdown (disabled) when SHDN is at or
1 F
Figure 1. Typical Application Circuit
OUT
OUT
OL
falls to zero volts and ERROR is open
Processor RESET Signal
rises above V
if ERROR is used as a
at 4.75 (typ.) for a 5.0V regulator and
GND
SHDN
OUT
V
C2 Requires Only
IN
TC1054VCT
(See Text)
remains stable and within regula-
IH
of the processor RESET input
ERROR
V
OUT
TH
= V
OUT
OUT
HYS
V
+
1 F
C1
falls out of regu-
falls to V
R1
1M
0.2 F
C2
.
V
OUT
BATTLOW
or RESET
TH
, and
4
Pull-up resistor R1 can be tied to V
voltage less than (V
Output Capacitor
mended. The output capacitor should have an effective
series resistance of 5
above 1MHz. A 1 F capacitor should be connected from
V
the regulator and the AC filter capacitor, or if a battery is
used as the power source. Aluminum electrolytic or tanta-
lum capacitor types can be used. (Since many aluminum
electrolytic capacitors freeze at approximately – 30 C, solid
tantalums are recommended for applications operating
below – 25 C.) When operating from sources other than
batteries, supply-noise rejection and transient response
can be improved by increasing the value of the input and
output capacitors and employing passive filtering tech-
niques.
Thermal Considerations
Thermal Shutdown
tor off when die temperature exceeds 160 C. The regulator
remains off until the die temperature drops to approximately
150 C.
Power Dissipation
rily a function of input and output voltage, and output current.
The following equation is used to calculate worst case
actual power dissipation:
IN
ERROR
50mA CMOS LDO WITH SHUTDOWN
to GND if there is more than 10 inches of wire between
A 1 F(min) capacitor from V
Integrated thermal protection circuitry shuts the regula-
The amount of power the regulator dissipates is prima-
V
OUT
V
V
V
TH
OL
IH
Figure 2. ERROR Output Operation
IN
= 0.3V).
or less, and a resonant frequency
AND ERROR OUTPUT
OUT
OUT
to ground is recom-
, V
HYSTERESIS (V
IN
or any other
HYS
)