TC2117-1.8DB MICROCHIP [Microchip Technology], TC2117-1.8DB Datasheet - Page 7

• Manufacturer Part Number: TC2117-1.8DB
• Description: 800 mA Fixed Low Dropout Positive Regulator
• Manufacturer: MICROCHIP [Microchip Technology]

4.0
The TC2117 is a precision, positive output LDO. Unlike
bipolar regulators, the TC2117 supply current does not
increase proportionally with load current. In addition,
V
entire 0 mA to 800 mA operating load range.
FIGURE 4-1:
4.1
A 1 µF (min) capacitor from V
The output capacitor should have an effective series
resistance of 0.2Ω to 10Ω. A 1 µF capacitor should be
connected from V
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.
4.2
4.2.1
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.
© 2006 Microchip Technology Inc.
OUT
Battery
remains stable and within regulation over the
DETAILED DESCRIPTION
Output Capacitor
Thermal Considerations
THERMAL SHUTDOWN
C
1µF
IN
1
to GND if there is more than 10
TYPICAL APPLICATION
CIRCUIT
V
GND
IN
TC2117
OUT
V
to ground is required.
OUT
C
1µF
2
V
OUT
4.2.2
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:
EQUATION 4-1:
The
(Equation
temperature (T
temperature (+125°C) and the thermal resistance from
junction-to-air (θ
EQUATION 4-2:
Table 4-1
mounted on a 1/16 inch, 2-layer PCB with 1 oz. copper
foil.
TABLE 4-1:
* Tab of device attached to topside copper.
2500 sq mm
1000 sq mm
1000 sq mm
1000 sq mm
225 sq mm
100 sq mm
(Topside)*
I
Copper
LOADMAX
V
Where:
Area
V
OUTMIN
INMAX
maximum
Where all terms are previously defined.
P
shows various values of θ
P
4-2) is a function of the maximum ambient
D
D
POWER DISSIPATION
=
= Worst-case actual power dissipation
= Maximum voltage on V
= Minimum regulator output voltage
= Maximum output (load) current
2500 sq mm
2500 sq mm
2500 sq mm
2500 sq mm
1000 sq mm
(Backside)
P
(
A
JA
0 sq mm
V
D
Copper
MAX
INMAX
THERMAL RESISTANCE
GUIDELINES FOR TC2117 IN
3-PIN SOT-223 PACKAGE
Area
MAX
).
), the maximum allowable die
allowable
= (T
–
J
V
MAX
OUTMIN
2500 sq mm
2500 sq mm
2500 sq mm
2500 sq mm
1000 sq mm
1000 sq mm
Board Area
θ
JA
– T
A
power
MAX
TC2117
)I
JA
LOADMAX
DS21665C-page 7
)
IN
for the TC2117
Resistance
Thermal
dissipation
45°C/W
45°C/W
53°C/W
59°C/W
52°C/W
55°C/W