300mA CMOS LDO with Shutdown, ERROR Output and Bypass
FEATURES
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Extremely Low Supply Current for Longer Battery
Life!
Very Low Dropout Voltage
Guaranteed 300mA Output
Standard or Custom Output Voltages
ERROR Output Can be Used as a Low Battery
Detector or Processor Reset Generator
Power-Saving Shutdown Mode
Bypass Input for Ultra-Quiet Operation
Over-Current and Over-Temperature Protection
Space-Saving MSOP Package Option
GENERAL DESCRIPTION
The TC1173 is a precision output (typically
±0.5%)
CMOS low dropout regulator. Total supply current is typi-
cally 50µA at full load
(20 to 60 times lower than in bipolar
regulators
!).
TC1173 key features include ultra low noise operation
(plus optional Bypass input); very low dropout voltage
(typically 240mV at full load) and internal feed-forward
compensation for fast response to step changes in load. An
error output (ERROR) is asserted when the TC1173 is out-
of-regulation (due to a low input voltage or excessive output
current). ERROR can be set as a low battery warning or as
a processor RESET signal (with the addition of an external
RC network). Supply current is reduced to 0.05µA (typical)
and V
OUT
and ERROR fall to zero when the shutdown input
is low.
The TC1173 incorporates both over-temperature and
over-current protection. The TC1173 is stable with an output
capacitor of only 1µF and has a maximum output current of
300mA.
APPLICATIONS
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Battery-Operated Systems
Portable Computers
Medical Instruments
Instrumentation
Cellular / GSM / PHS Phones
Linear Post-Regulator for SMPS
Pagers
ORDERING INFORMATION
Part
Number
TC1173-xxVOA
TC1173-xxVUA
Package
8-Pin SOIC
8-Pin MSOP
Junction
Temp. Range
– 40°C to +125°C
– 40°C to +125°C
TYPICAL APPLICATION
1
C1
1µF
2
8
V
OUT
V
IN
V
IN
GND
NC
7
R3
1M
TC1173
3
NC
SHDN
6
Available Output Voltages:
2.5, 2.8, 3.0, 3.3, 5.0
xx indicates output voltages
Other output voltages are available. Please contact TelCom
Semiconductor for details.
4
Bypass
ERROR
5
ERROR
PIN CONFIGURATION
MSOP
V
OUT
GND
NC
Bypass
1
2
3
4
8
7
C
BYPASS
470pF
(Optional)
Shutdown Control
(from Power Control Logic)
TC1173VUA
6
5
V
IN
NC
SHDN
ERROR
SOIC
V
OUT
1
GND 2
8 V
IN
7 NC
NC 3 TC1173VOA 6 SHDN
Bypass 4
5 ERROR
TC1173-2 2/2/00 TelCom Semiconductor reserves the right to make changes in the circuitry and specifications of its devices.
300mA CMOS LDO With Shutdown,
ERROR Output, And Bypass
TC1173
ABSOLUTE MAXIMUM RATINGS*
Input Voltage .............................................................. 6.5V
Output Voltage ........................... (V
SS
– 0.3) to (V
IN
+ 0.3)
Power Dissipation .................... Internally Limited (Note 7)
Operating Temperature .................... – 40°C < T
J
< 125°C
Storage Temperature ............................ – 65°C to +150°C
Maximum Voltage on Any Pin ............ V
IN
+0.3V to – 0.3V
Lead Temperature (Soldering, 10 Sec.) ................ +300°C
*Absolute Maximum Ratings indicate device operation limits beyond dam-
age may occur. Device operation beyond the limits listed in
Electrical
Characteristics
is not recommended.
ELECTRICAL CHARACTERISTICS:
V
IN
= V
OUT
+ 1V, I
L
= 0.1µA, C
L
= 3.3µF, SHDN > V
IH
, T
A
= 25°C, unless otherwise noted.
BOLDFACE
type specifications apply for junction temperatures of – 40°C to +125°C
Symbol
V
IN
I
OUT
MAX
V
OUT
∆V
OUT
/∆T
∆V
OUT
/∆V
IN
∆V
OUT
/V
OUT
V
IN
– V
OUT
Parameter
Input Operating Voltage
Maximum Output Current
Output Voltage
V
OUT
Temperature Coefficient
Line Regulation
Load Regulation
Dropout Voltage (Note 4)
Test Conditions
Min
—
300
—
V
R
- 2.5%
—
—
—
—
Typ
—
—
±
0.5%
—
40
0.05
0.5
20
80
240
50
0.05
60
550
0.04
260
Max
6.0
—
—
V
R
+ 2.5%
—
0.35
2.0
30
160
480
90
0.5
—
650
—
—
Units
V
mA
V
ppm/°C
%
%
mV
Note 1
Note 2
(V
R
+ 1V) < V
IN
< 6V
I
L
= 0.1mA to I
OUT
MAX
(Note 3)
I
L
= 0.1mA
I
L
= 100mA
I
L
= 300mA
SHDN = V
IH
SHDN = 0V
F
RE
≤
1kHz
V
OUT
= 0V
Note 5
F = 1kHz, C
OUT
= 1µF,
R
LOAD
= 50Ω
V
R
I
SS1
I
SS2
PSRR
I
OUT
SC
∆V
OUT
∆P
D
eN
Supply Current
Shutdown Supply Current
Power Supply Rejection Ratio
Output Short Circuit Current
Thermal Regulation
Output Noise
—
—
—
—
—
—
µA
µA
dB
mA
V/W
nV/√Hz
SHDN Input
V
IH
V
IL
SHDN Input High Threshold
SHDN Input Low Threshold
45
—
—
—
—
15
%V
IN
%V
IN
ERROR Output
V
MIN
V
OL
V
TH
V
OL
Minimum Operating Voltage
Output Logic Low Voltage
ERROR Threshold Voltage
ERROR Positive Hysteresis
1mA Flows to ERROR
Note 7
1.0
—
—
—
—
—
0.95 x V
R
50
—
400
—
—
V
mV
V
mV
NOTES:
1. V
R
is the user-programmed regulator output voltage setting.
2. T
C
V
OUT
= (V
OUTMAX
– V
OUTMIN
) x 10
6
V
OUT
x
∆T
3. Regulation is measured at a constant junction temperature using low duty cycle pulse testing. Load regulation is tested over a load range from 0.1mA
to the maximum specified output current. Changes in output voltage due to heating effects are covered by the thermal regulation specification.
4. Dropout voltage is defined as the input to output differential at which the output voltage drops 2% below its nominal value measured at a 1V differential.
5. 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.
6. 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.
7. Hysteresis voltage is referenced to V
R
.
TC1173-2
2/2/00
2
300mA CMOS LDO With Shutdown,
ERROR Output, And Bypass
TC1173
DETAILED DESCRIPTION
The TC1173 is a fixed output, low drop-out regulator.
Unlike bipolar regulators, the TC1173 supply current does not
increase with load current. In addition, V
OUT
remains stable and
within regulation at very low load currents (an important consid-
eration in RTC and CMOS RAM battery back-up applications).
TC1173 pin functions are detailed below:
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),
V
OUT
falls to zero and ERROR is disabled.
ERROR Output
ERROR is driven low whenever V
OUT
falls out of regu-
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
OUT
regard-
less of the programmed output voltage value (e.g., ERROR
= V
OL
at 4.75V (typ) for a 5.0V regulator and 2.85V (typ) for
a 3.0V regulator). ERROR output operation is shown in
Figure 2. Note that ERROR is active when V
OUT
is at or
below V
TH
, and inactive when V
OUT
is above V
TH
+ V
H
.
As shown in Figure 1, ERROR can be used as a battery
low flag, or as a processor RESET signal (with the addition
of timing capacitor C2). R1 x C3 should be chosen to
maintain ERROR below V
IH
of the processor RESET input
for at least 200msec to allow time for the system to stabilize.
Pull-up resistor R1 can be tied to V
OUT
, V
IN
or any other
voltage less than (V
IN
+ 0.3V.)
V
OUT
PIN DESCRIPTIONS
Pin
No.
1
2
3
4
5
Symbol
V
OUT
GND
NC
Bypass
ERROR
Description
Regulated voltage output
Ground terminal
No connect
Reference bypass input. Connecting a 470pF
to this input further reduces output noise.
Out-of-Regulation Flag (Open Drain Out-
put). This output goes low when V
OUT
is out-
of-tolerance by approximately -5%.
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 0.05µA (typical).
No connect
Unregulated supply input
6
SHDN
7
8
NC
V
IN
V
TH
Hysteresis (V
H
)
Figure 1 shows a typical application circuit. The regula-
tor is enabled any time the shutdown input (SHDN) is above
V
IH
, and shutdown (disabled) when SHDN is at or below V
IL
.
ERROR
V
IH
V
OL
V
OUT
1
C1
1µF
2
V
OUT
V
IN
8
Figure 2: ERROR Output Operation
V
IN
GND
NC
7
R3
1M
TC1173
3
NC
SHDN
6
4
Bypass
ERROR
5
ERROR
C
BYPASS
470pF
(Optional)
Shutdown Control
(from Power Control Logic)
Output Capacitor
A 1µF (min) capacitor from V
OUT
to ground is recom-
mended. The output capacitor should have an effective
series resistance 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 electro-
lytic 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.
3
Figure 1: Typical Application Circuit
TC1173-2 2/2/00
300mA CMOS LDO With Shutdown,
ERROR Output, And Bypass
TC1173
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.
Equation 1 can be used in conjunction with Equation 2
to ensure regulator thermal operation is within limits. For
example:
GIVEN:
V
IN
MAX
= 3.0V
±
10%
V
OUT
MIN
= 2.7V
±
0.5%
I
LOADMAX
= 250mA
T
J
MAX
= 125°C
T
A
MAX
= 55°C
JA
= 200°C/W
8-Pin MSOP Package
1. Actual power dissipation
2. Maximum allowable dissipation
Thermal Considerations
Thermal Shutdown
Integrated thermal protection circuitry shuts the regula-
tor off when die temperature exceeds 150°C. The regulator
remains off until the die temperature drops to approximately
140°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:
P
D
≈
(V
IN
MAX
– V
OUT
MIN
)I
LOAD
MAX
Where:
P
D
=
V
IN
MAX
=
V
OUT
MIN
=
I
LOAD
MAX
=
worst case actual power dissipation
maximum voltage on V
IN
minimum regulator output voltage
maximum output (load) current
Equation 1.
FIND:
Actual power dissipation:
P
D
≈
(V
IN
MAX
- V
OUT
MIN
)I
LOAD
MAX
= [(3.0 x 1.1) - (2.7 x .995)]250 x 10
-3
= 155mW
Maximum allowable power dissipation:
P
D
≈
(T
JMAX
– T
AMAX
)
JA
= (125 – 55)
200
= 350mW
In this example, the TC1173 dissipates a maximum of
only 155mW; far below the allowable limit of 350mW. In a
similar manner, Equation 1 and Equation 2 can be used to
calculate maximum current and/or input voltage limits. For
example, the maximum allowable V
IN
is found by substitut-
ing the maximum allowable power dissipation of 350mW
into Equation 1, from which V
IN
MAX
= 4.1V.
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
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
A
MAX
),
the maximum allowable die temperature (125°C), and the
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