REV. 0

ADP3510

–12–

Power On Delay

The power-on delay block in the ADP3510 controls the turn-on

sequence of VCORE, VIO, and VAN. Asserting a power-on in one

of the four above methods will start the LDOs in the following

sequence:

1. The VMEM LDO will start up.

2. The VIO and VAN outputs will be discharged by the power-

on delay block. The discharge delay time is set by the value

of the PDCAP.

3. After the discharge time has expired, the VCORE LDO is

allowed to start up.

4. When the output of VCORE exceeds 1.2 V, the VIO and

VAN LDOs are allowed to start up.

The power-on delay is set by an external capacitor on PDCAP:

t

ms

nF

C

PD

PDCAP

=¥

08

.

(1)

See Figure 5 for the power-up timing sequence.

3.0V

3.0V

1.8V

1.2V

INTERNAL

POWER ON*

POWER-ON

DELAY

V10, VAN < VCORE

UNTIL VCORE > 1.2V

*

PWRONIN or CHRDET

or ALARM or PWRONKEY

V10, VAN

VCORE

VMEM

Figure 5. Power-Up Timing Diagram

Deep Discharge Lockout (DDLO)

The DDLO block in the ADP3510 will shut down the handset in

the event the software fails to turn off the phone when the battery

drops below 2.9 V to 3.0 V. The DDLO will shut down the

handset when the battery falls below 2.4 V to prevent further

discharge and damage to the cell.

Undervoltage Lockout (UVLO)

The UVLO function in the ADP3510 prevents startup when the

initial voltage of the battery is below the 3.2 V threshold. If the

battery voltage is this low with no load, there is insufficient

capacity left to run the handset. When the battery is greater than

3.2 V, such as inserting a fresh battery, the UVLO comparator trips

and the threshold is reduced to 3.0 V. This allows the handset to

start normally until the battery decays to below 3.0 V. Note that

the DDLO has enabled the RTC LDO under this condition.

Once the system is started and the core, memory, analog, and

IO LDOs are up and running, the UVLO function is entirely disabled.

The ADP3510 is then allowed to run until the battery voltage

reaches the DDLO threshold, typically 2.4 V. Normally, the

battery voltage is monitored by the baseband processor and

usually shuts the phone off at around 3.0 V.

If the handset is off and the battery voltage drops below 3.0 V,

the UVLO circuit disables startup and puts the ADP3510 into

UVLO shutdown mode. In this mode, the ADP3510 draws very

low quiescent current, typically 30

mA. The RTC LDO is still

running until the DDLO disables it. In this mode, the

ADP3510 draws 5

mA of quiescent current. NiMH batteries can

reverse polarity if the 3-cell battery voltage drops below 3.0 V,

which will degrade the battery’s performance. Lithium Ion bat-

teries will lose their capacity if over discharged repeatedly so

minimizing the quiescent currents helps prevent battery damage.

RESET

The ADP3510 contains a reset circuit that is active both at power-up

and power-down. The RESET pin is held low at initial power-

up. An internal power good signal is generated by the IO LDO

when its output is in regulation which starts the reset delay timer.

The delay is set by an external capacitor on RESCAP:

t

ms

nF

C

RESET

RESCAP

=¥

15

.

(2)

Should the IO or MEM LDO drop out of regulation, the

RESET signal will go low and remain low until the IO and

MEM LDO outputs are back in regulation and the RESET

timer has timed out. At power-off, RESET will be kept low to

prevent any baseband processor starts.

Over-Temperature Protection

In case of a failure that causes excess power dissipation to the IC,

the thermal shutdown function will be activated. The maximum

die temperature for the ADP3510 is 125 C. If the die temperature

exceeds 160 C, the ADP3510 will disable all the LDOs except

the RTC LDO. The LDOs will not be re-enabled before the die

temperature is below 125 C, regardless of the state of PWRONKEY,

PWRONIN, ALARM, and CHRDET. This ensures that the

handset will always power-off before the ADP3510 exceeds its

absolute maximum thermal ratings.

Battery Charging

The ADP3510 battery charger can be used with lithium ion

(Li+) and nickel metal hydride (NiMH) batteries. The charger

initialization, trickle charging, and Li+ charging are imple-

mented in hardware. Battery type determination and NiMH

charging must be implemented in software.

The charger block works in three different modes:

∑ Low Current (Trickle) Charging

∑ Lithium Ion Charging

∑ Nickel Metal Hydride Charging

See Figure 6 for the battery charger flowchart.