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Data Sheet

ADP5034

Rev. E | Page 17 of 28

Thermal Protection

In the event that the junction temperature rises above 150°C,

the thermal shutdown circuit turns off all the regulators. Extreme

junction temperatures can be the result of high current opera-

tion, poor circuit board design, or high ambient temperature.

A 20°C hysteresis is included so that when thermal shutdown

occurs, the regulators do not return to operation until the on-chip

temperature drops below 130°C. When coming out of thermal

shutdown, all regulators restart with soft start control.

Undervoltage Lockout

To protect against battery discharge, undervoltage lockout

(UVLO) circuitry is integrated into the system. If the input

voltage on AVIN drops below a typical 2.15 V UVLO threshold,

all channels shut down. In the buck channels, both the power

switch and the synchronous rectifier turn off. When the voltage

on AVIN rises above the UVLO threshold, the part is enabled

once more.

Alternatively, the user can select device models with a UVLO

set at a higher level, suitable for 5 V supply applications. For

these models, the device reaches the turn-off threshold when

the input supply drops to 3.65 V typical.

In case of a thermal or UVLO event, the active pull-downs (if

factory enabled) are enabled to discharge the output capacitors

quickly. The pull-down resistors remain engaged until the

thermal fault event is no longer present or the input supply

voltage falls below the VPOR voltage level. The typical value of

VPOR is approximately 1 V.

Enable/Shutdown

The ADP5034 has an individual control pin for each regulator.

A logic level high applied to the ENx pin activates a regulator,

whereas a logic level low turns off a regulator.

Figure 47 shows the regulator activation timings for the

ADP5034 when all enable pins are connected to AVIN. Also

shown is the active pull-down activation.

AVIN

VOUT3

VOUT4

VOUT1

VUVLO

VOUT2

VPOR

BUCK2

PULL-DOWN

BUCK1,

LDO1,

LDO2

PULL-DOWNS

50µs (MIN)

30µs

(MIN)

50µs (MIN)

30µs

(MIN)

Figure 47. Regulator Sequencing on the ADP5034 (EN1 = EN2 = EN3 = EN4 = VAVIN)

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