NCP370(2008) 查看數據表（PDF） - ON Semiconductor

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NCP370
(Rev.:2008)

Positive and Negative Overvoltage Protection with Internal Low RON N-MOSFETs and Reverse Charge Control Pin

ON Semiconductor 

NCP370

Characteristics

Symbols

Conditions

Min Typ Max Unit

TIMINGS

DIRECT MODE

Start Up Delay

FLAG Going Up Delay

Turn Off Delay

Alert Delay

Disable Time

ton

From Vin > UVLO to Vout w 0.3 V

20

30

40 ms

tstart

From Vout > 0.3 V to FLAG = 1.2 V

20

30

40 ms

toff

From Vin > OVLO to Vout v 0.3 V

Vin Increasing from 5 V to 8 V at 3 V/ms

1.5 5.0 ms

tstop

From Vin > OVLO to FLAG v 0.4 V See Figure

1.5

ms

3 and 9 Vin Increasing from 5 V to 8 V at 3 V/ms

tdis

REV = 1.2 V, From DIR = 0.4 V to 1.2 V to Vout

2.5

ms

v 0.3 V

REVERSE MODE

Reverse Start Up Delay

tonREV

Vout w 2.5 V, From REV = 1.2 to 0.55 to

Vin w 0.3 V, Reverse Mode

0.6 1.2 1.8 ms

Reverse FLAG Going Up Delay

tstartREV

From Vin w 0.3 V FLAG = 1.2 V, Reverse Mode 0.6

1.2

1.8 ms

Rearming Reverse Delay

tRRD

Vout > 2.5 V, Rin = 1 W, Reverse Mode

20

30

40 ms

Over Current Regulation Time

tREG

Vout > 2.6, Vin > 0.3 V, Reverse Mode

0.5 1.2 1.8 ms

OCP Delay Time

tOCP

From Ireverse > Ilim, 1 A/1 ms

5

ms

Reverse Disable Time

tREVDIS

From REV = 0.55 V to 1.2 V, to Vin < 0.3 V.

Vout = 5 V

200

ms

NOTE: Electrical parameters are guaranteed by correlation across the full range of temperature.

TYPICAL OPERATING CHARACTERISTICS

Operation

The NCP370 provides overvoltage protection for positive

and negative voltages, up to 28 V or down to −28 V on

IN pins. At powerup, with DIR pin = low, REV = high, the

output rises 30 ms after the input rises above the UVLO. The

NCP370 provides a FLAG output, which alerts the system

that a fault has occurred. The FLAG signal rises 30 ms after

the output signal rises.

A Reverse Mode is available when an accessory is

connected on IN pins and the internal battery is applied on

the OUT pin, allowing the accessory to be powered. In this

mode, no supply must be connected on IN pins and REV pin

must be tied to low level. The NCP370 provides overcurrent

protection for the battery from current faults in the

accessory.

Undervoltage Lockout (UVLO)

To ensure proper turn−on operation from AC/DC (or Wall

adapter charging) under any conditions, the device has a

built−in undervoltage lock out (UVLO) circuit. During

positive going slope on Vin, the output remains disconnected

from input until Vin voltage is above UVLO. The FLAG

output will be low as long as Vin has not reached UVLO

threshold. This circuit has a 60 mV hysteresis to provide

noise immunity to transient conditions.

In Reverse Mode (REV pin v 0.55 V, DIR w 1.2 V),

UVLO and OVLO comparators are inactivated.

Overvoltage Lockout (OVLO)

To protect connected systems on Vout pin from

overvoltage, the device has a built−in overvoltage lock out

(OVLO) circuit. During overvoltage condition, the output is

disabled as long as the input voltage exceeds OVLO.

Additional OVLO thresholds can be manufactured

(Please contact your ON Semiconductor representative for

availability).

FLAG output will be low since Vin is higher than OVLO.

This circuit has a 80 mV hysteresis to provide noise

immunity to transient conditions.

Oversystem Voltage Lockout (OVLO00)

A second overvoltage comparator is available for

supplying the sytem (output) by the Wall Adaptor (input) by

setting DIR = low and REV = low. The RDS(on) will be

higher during this mode allowing to handle few 10 mA.

This additional comparator allows to put higher input

voltage (OVLO = 8.27 V typical) on the NCP370 during test

production sequence (I.E: One Time Programming of the

cell phone, PDA). This parameter is 25°C guaranteed only.

FLAG Output

The NCP370 provides a FLAG output which alerts that a

fault has occurred. As soon as a fault state is detected by the

NCP370 (see Figure 3), the FLAG pin output goes low,

alerting the micro−controller to take appropriate action.

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