MP5002 – 3.3V, 1A-3A PROGRAMMABLE CURRENT LIMIT SWITCH

MP5002 Rev. 0.93

www.MonolithicPower.com

10

10/15/2010

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The fault flag is an internal flip-flop that can be

set or reset under various conditions:

1. Thermal Shutdown: set fault flag

2. Under Voltage: reset fault flag

3. Low voltage on Enable/Fault pin: reset

fault flag

4. Mid voltage on Enable/Fault pin: no

effect

5. Under a fault, the Enable/Fault pin is

driven to the mid level.

There are 4 types of faults, and each fault has a

direct and indirect effect on the Enable/Fault pin

and the internal fault flag. In a typical application

where there are multiple MP5002 chips in a

system, the enable/fault lines are typically

connected together.

Table 3—Fault Function Influence in Application

Fault description

Internal action

Effect on Fault

Pin

Effect on

Flag

Effect on secondary

Part

Short/over current

Limit current

none

none

none

Under Voltage

Output is turned off

Internally drives

Enable/Fault pin to

Logic low

Flag is

reset

Secondary part output is

disabled, and fault flag is

reset.

Over Voltage

Limit output voltage

None

None

None

Thermal Shutdown

Shutdown part. The

part is latched off

until a UVLO or

externally driven to

ground.

Internally drives

Enable/Fault pin

to mid level

Flag is Set

Secondary part output is

disabled.

UNDER VOLTAGE LOCK OUT OPERATION

If the supply (input) is below the UVLO threshold,

the output is disabled, and the fault line is driven

low. When the supply goes above the UVLO

threshold, the output is enabled and the fault line

is released. When the fault line is released it will

external pull up resistor is required. In addition,

the pull up voltage is limited to 5 volts.

THERMAL PROTECTION

When thermal protection is triggered, the output

is disabled and the fault line is driven to the mid

level. The thermal fault condition is latched

(meaning the fault flag is set), and the part will

remain latched off until the fault (enable) line is

brought low. Cycling the power below the UVLO

threshold will also reset the fault flag.