NCV8702(2013) 데이터 시트보기 (PDF) - ON Semiconductor

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NCV8702
(Rev.:2013)

200 mA, Ultra-Low Quiescent Current, Ultra-Low Noise, LDO Linear Voltage Regulator

ON Semiconductor 

NCV8702

APPLICATIONS INFORMATION

Enable Operation

The NCV8702 uses the EN pin to enable/disable its output

and to deactivate/activate the active discharge function.

If the EN pin voltage is <0.4 V the device is guaranteed to

be disabled. The pass transistor is turned−off so that there is

virtually no current flow between the IN and OUT. The

active discharge transistor is active so that the output voltage

VOUT is pulled to GND through a 1 kW resistor. In the

disable state the device consumes as low as typ. 10 nA from

the VIN.

If the EN pin voltage >0.9 V the device is guaranteed to

be enabled. The NCV8702 regulates the output voltage and

the active discharge transistor is turned−off.

The EN pin has internal pull−down current source with

typ. value of 110 nA which assures that the device is

turned−off when the EN pin is not connected. A build in

2 mV of hysteresis in the EN prevents from periodic on/off

oscillations that can occur due to noise.

In the case where the EN function isn’t required the EN

pin should be tied directly to IN.

Undervoltage Lockout

The internal UVLO circuitry assures that the device

becomes disabled when the VIN falls below typ. 1.5 V. When

the VIN voltage ramps−up the NCV8702 becomes enabled,

if VIN rises above typ. 1.6 V. The 100 mV hysteresis prevents

on/off oscillations that can occur due to noise on VIN line.

Reverse Current

The PMOS pass transistor has an inherent body diode

which will be forward biased in the case that VOUT > VIN.

Due to this fact in cases where the extended reverse current

condition is anticipated the device may require additional

external protection.

Output Current Limit

Output Current is internally limited within the IC to a

typical 380 mA. The NCV8702 will source this amount of

current measured with the output voltage 100 mV lower than

the nominal VOUT. If the Output Voltage is directly shorted

to ground (VOUT = 0 V), the short circuit protection will

limit the output current to 390 mA (typ). The current limit

and short circuit protection will work properly up to VIN =

5.5 V at TA = 25C. There is no limitation for the short circuit

duration.

Thermal Shutdown

When the die temperature exceeds the Thermal Shutdown

threshold (TSD − 160C typical), Thermal Shutdown event

is detected and the device is disabled. The IC will remain in

this state until the die temperature decreases below the

Thermal Shutdown Reset threshold (TSDU − 140C typical).

Once the IC temperature falls below the 140C the LDO is

enabled again. The thermal shutdown feature provides

protection from a catastrophic device failure due to

accidental overheating. This protection is not intended to be

used as a substitute for proper heat sinking.

Power Dissipation

As power dissipated in the NCV8702 increases, it might

become necessary to provide some thermal relief. The

maximum power dissipation supported by the device is

dependent upon board design and layout. Mounting pad

configuration on the PCB, the board material, and the

ambient temperature affect the rate of junction temperature

rise for the part.

The maximum power dissipation the NCV8702 can

handle is given by:

ƪ ƫ PD(MAX) +

TJ(MAX) * TA

qJA

(eq. 1)

The power dissipated by the NCV8702 for given

application conditions can be calculated from the following

equations:

PD [ VINǒIGND@IOUTǓ ) IOUTǒVIN * VOUTǓ (eq. 2)

330

0.65

310

0.60

290

0.55

270

PD(MAX), TA = 25C, 2 OZ CU 0.50

250

0.45

230

210

190 PD(MAX), TA = 25C, 1 OZ CU

170

0.40

qJA, 1 OZ CU

0.35

qJA, 2 OZ CU 0.30

0.25

150

0

0.20

100 200 300 400 500 600 700

PCB COPPER AREA (mm2)

Figure 62. qJA and PD(MAX) vs. Copper Area (TSOP5)

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