# Automotive Linear Voltage Regulator LDO TLF4277-2LD for Active Antenna Supplies: typical application circuit

### Low Drop Out Linear Voltage Regulator TLF4277-2LD

Application Circuit

{ Please double click here to enter design criteria }

{ Select required Voltage }

V_OUT := 5;

{ Select known Resistor: 1 for R1, 2 for R2 }

R1orR2 := 1;

{ Select Value for known Resistor (R1 or R2) }

R := 38k;

{ Vref defined as a typical value of 1.2 V in the model }

Vref := 1.2;

{ Output Capacitance }

C_OUT := 2.2u;

{ Equivalent Series Resistance for CQ }

Resr_cout := 13m;

{ Current Sense Output Resistor }

R_CSO := 820;

{ Current Sense Output Capacitor }

C_CSO := 2.2u;

{ Number of Thermal Model }

THERMAL_MODEL := 1;

{ Ambient Temperature }

T_AMB := 25;

The resistor divider for a specific output voltage can

be calculated as follows:

VQ = ((R1+R2)/R2)*Vref_int

therefore R1 = ((VQ/Vref_int)-1)*R2

For this model, Vref_int = 1.2 V and R2 < 27 kΩ

For VQ_max = 20 V and R1_max = 9*R2_max

therefore R1_max < 243 kΩ

The typical value of Vref_int is specified as typical 1.19 V in

the datasheet, but should be tweaked to actual simulated

value in the design parameters for accurate results.

Thermal model description:

Thermal Model = 4: JEDEC 1s0p, 600mm2 cooling area

Thermal Model = 5: JEDEC 1s0p, footprint

Thermal Model = 6: JEDEC 2s2p

Thermal Model = 7: No self-heating, only TEMP value used as temperature

Model performance:

- dynamic behavior partially modelled

- loop behavior is idealized

- the thermal simulations represent an approximation of the actual thermal

behavior of the device according to the JEDEC standards at Power = 2.55 Watts

and Temperature = 85 °C

The TLF4277-2LD is the ideal companion IC to supply active antennas for car

infotainment applications. The adjustable output voltage makes the TLF4277-2LD

capable of supplying the majority of standard active antennas such as: FM/AM,

DAB, XM and SIRIUS.

The TLF4277-2LD is a monolithic integrated low drop out voltage regulator

capable of supplying loads up to 300 mA. TLF4277-2LD provides an adjustable

output voltage in a range from 5 V up to 12 V. The integrated current

monitor function is a unique feature that provides diagnosis and system

protection functionality.

Via the enable function the IC can be disabled to lower the power consumption.

Technical Assistance

Product info: TLF4277-2LD

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