4. Regulation is measured at a constant junction temperature using low duty cycle pulse testing. Load regulation is tested over a load range from 1.0mA
to the maximum specified output current. Changes in output voltage due to heating effects are covered by the thermal regulation specification.
5. Dropout voltage is defined as the input to output differential at which the output voltage drops 2% below its nominal value at a 1V differential.
6. Thermal Regulation is defined as the change in output voltage at a time T after a change in power dissipation is applied, excluding load or
line regulation effects. Specifications are for a current pulse equal to I
LMAX
at V
IN
= 6V for T = 10msec.
7. The maximum allowable power dissipation is a function of ambient temperature, the maximum allowable junction temperature and the thermal
resistance from junction-to-air (i.e. T
A
, T
J
,
θ
JA
). Exceeding the maximum allowable power dissipation causes the device to initiate thermal
shutdown. Please see
Thermal Considerations
section of this data sheet for more details.
8. Apply for Junction Temperatures of –40°C to +85°C.
TC1014/TC1015/TC1185-3
1/20/00
2
50mA, 100mA, 150mA CMOS LDOs
with Shutdown and
Reference Bypass
TC1014
TC1015
TC1185
PIN DESCRIPTION
Pin No.
(5-Pin SOT-23A) Symbol
1
2
3
V
IN
GND
SHDN
Description
Unregulated supply input.
Ground terminal.
Shutdown control input. The regulator is fully enabled when a logic high is applied to this
input. The regulator enters shutdown when a logic low is applied to this input. During
shutdown, output voltage falls to zero, and supply current is reduced to 0.5µA (max).
Reference bypass input. Connecting a 470pF to this input further reduces output noise.
Regulated voltage output.
4
5
Bypass
V
OUT
DETAILED DESCRIPTION
The TC1014, TC1015, and TC1185 are precision fixed
output voltage regulators. (If an adjustable version is de-
sired, please see the TC1070, TC1071, or TC1187 data
sheets.) Unlike bipolar regulators, the TC1014, TC1015,
and TC1185 supply current does not increase with load
current. In addition, V
OUT
remains stable and within regula-
tion at very low load currents (an important consideration in
RTC and CMOS RAM battery back-up applications).
Figure 1 shows a typical application circuit. The regula-
tor is enabled any time the shutdown input (SHDN) is at or
above V
IH
, and shutdown (disabled) when SHDN is at or
below V
IL
. SHDN may be controlled by a CMOS logic gate,
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 0.05µA
(typical) and V
OUT
falls to zero volts.
Bypass Input
A 470pF capacitor connected from the Bypass input to
ground reduces noise present on the internal reference,
which in turn significantly reduces output noise. If output
noise is not a concern, this input may be left unconnected.
Larger capacitor values may be used, but results in a longer
time period to rated output voltage when power is initially
applied.
Output Capacitor
A 1µF (min) capacitor from V
OUT
to ground is required.
The output capacitor should have an effective series resis-
tance of 5Ω or less. A 1µF capacitor should be connected
from V
IN
to GND if there is more than 10 inches of wire
between the regulator and the AC filter capacitor, or if a
battery is used as the power source. Aluminum electrolytic
or tantalum 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
techniques.
V
IN
1µF
V
OUT
1µF
V
OUT
BATTERY
GND
TC1014
TC1015
TC1185
SHDN
Bypass
470pF
Reference
Bypass Cap
(Optional)
Shutdown Control
(to CMOS Logic or Tie to V
IN
if Unused)
Thermal Considerations
Thermal Shutdown
Integrated thermal protection circuitry shuts the regula-
tor off when die temperature exceeds 160°C. The regulator
remains off until the die temperature drops to approximately
150°C.
Power Dissipation
The amount of power the regulator dissipates is prima-
rily a function of input and output voltage, and output current.
The following equation is used to calculate worst case
actual
power dissipation:
Figure 1. Typical Application Circuit
TC1014/TC1015/TC1185-3 1/20/00
3
TC1014
TC1015
TC1185
P
D
≈
(V
INMAX
– V
OUTMIN
)I
LOADMAX
Where:
P
D
V
INMAX
V
OUTMIN
I
LOADMAX
= Worst case actual power dissipation
= Maximum voltage on V
IN
= Minimum regulator output voltage
= Maximum output (load) current
Equation 1.
50mA, 100mA, 150mA CMOS LDOs
with Shutdown and
Reference Bypass
Maximum allowable power dissipation:
P
DMAX
= (T
JMAX
– T
AMAX
)
θ
JA
= (125 – 55)
220
= 318mW
In this example, the TC1014 dissipates a maximum of
only 26.7 mW; far below the allowable limit of 318 mW. In a
similar manner, Equation 1 and Equation 2 can be used to
calculate maximum current and/or input voltage limits.
Layout Considerations
The primary path of heat conduction out of the package
is via the package leads. Therefore, layouts having a ground
plane, wide traces at the pads, and wide power supply bus
lines combine to lower
θ
JA
and, therefore, increase the
maximum allowable power dissipation limit.
The maximum
allowable
power dissipation (Equation 2)
is a function of the maximum ambient temperature (T
AMAX
),
the maximum allowable die temperature (125°C) and the
thermal resistance from junction-to-air (θ
JA
). The
5-Pin SOT-23A package has a
θ
JA
of approximately
220
°
C/
Watt
when mounted on a single layer FR4 dielectric copper
clad PC board.
P
D MAX
= (T
JMAX
– T
AMAX)
θ
JA
Where all terms are previously defined.
Equation 2.
Equation 1 can be used in conjunction with Equation 2
to ensure regulator thermal operation is within limits. For
example:
Given:
V
INMAX
= 3.0V +10%
V
OUTMIN
= 2.7V – 2.5%
I
LOADMAX
= 40mA
T
JMAX
= 125°C
T
AMAX
= 55°C
Find:
1. Actual power dissipation
2. Maximum allowable dissipation
Actual power dissipation:
P
D
≈
(V
INMAX
– V
OUTMIN
)I
LOADMAX
= [(3.0 x 1.1) – (2.7 x .975)]40 x 10
–3
= 26.7mW
TC1014/TC1015/TC1185-3
1/20/00
4
50mA, 100mA, 150mA CMOS LDOs
with Shutdown and
Reference Bypass
TC1014
TC1015
TC1185
TYPICAL CHARACTERISTICS:
(Unless otherwise specified, all parts are measured at Temperature = 25
DSP 与 ARM 处理器
