MAX1587AETL-T Maxim Integrated Products, MAX1587AETL-T Datasheet - Page 18

• Manufacturer Part Number: MAX1587AETL-T
• Description: Other Power Management PMICs w/Dynamic Core for PDAs
• Manufacturer: Maxim Integrated Products

High-Efficiency, Low-I
Dynamic Core for PDAs and Smart Phones
The MAX1586/MAX1587 power-management ICs are
optimized for devices using Intel XScale microproces-
sors, including third-generation smart cell phones,
PDAs, internet appliances, and other portable devices
requiring substantial computing and multimedia
capability at low power. The MAX1586A/MAX1586B/
MAX1587A comply with Intel Processor Power
specifications.
The ICs integrate seven high-performance, low-operat-
ing-current power supplies along with supervisory and
management functions. Regulator outputs include three
step-down DC-DC outputs (V1, V2, and V3), three lin-
ear regulators (V4, V5, and V6), and one always-on out-
put, V7 (Intel VCC_BATT). The V1 step-down DC-DC
converter provides 3.3V or adjustable output voltage for
I/O and peripherals. The V2 step-down DC-DC convert-
er on the MAX1586A and MAX1587A is preset for 1.8V
or 2.5V, while the MAX1586B V2 supply is preset for
3.3V or 2.5V. V2 can also be adjusted with external
resistors on all parts. The V3 step-down DC-DC con-
verter provides a serial-programmed output for power-
ing microprocessor cores. The three linear regulators
(V4, V5, and V6) provide power for PLL, SRAM, and
USIM.
To minimize sleep-state quiescent current, V1 and V2
have bypass “sleep” LDOs that can be activated to
minimize battery drain when output current is very low.
Other functions include separate on/off control for all
DC-DC converters, low-battery and dead-battery
detection, a power-OK output, a backup-battery input,
and a two-wire serial interface.
All DC-DC outputs use fast, 1MHz PWM switching and
small external components. They operate with fixed-fre-
quency PWM control and automatically switch from
PWM to skip-mode operation at light loads to reduce
operating current and extend battery life. The V3 core
output is capable of forced-PWM operation at all loads.
The 2.6V to 5.5V input voltage range allows 1-cell Li+,
3-cell NiMH, or a regulated 5V input.
The following power-supply descriptions include the
Intel terms for the various voltages in parenthesis. For
example, the MAX1586/MAX1587 V1 output is referred
to as VCC_IO in Intel documentation. See Figure 1.
V1 is a 1MHz current-mode step-down converter. The V1
output voltage can be preset to 3.3V or adjusted using a
resistor voltage-divider. V1 supplies loads up to 1300mA.
Idle Mode is a trademark of Maxim Integrated Products, Inc.
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V1 and V2 (VCC_IO, VCC_MEM)
Step-Down DC-DC Converters
Detailed Description
Q
PMICs with
V2 is also a 1MHz current-mode step-down converter.
The V2 step-down DC-DC converter on the MAX1586A
and MAX1587A is preset for 1.8V or 2.5V, while the
MAX1586B V2 supply is preset for 3.3V or 2.5V. V2 can
also be adjusted with external resistors on all parts. V2
supplies loads up to 900mA.
Under moderate to heavy loading, the converters operate
in a low-noise PWM mode with constant frequency and
modulated pulse width. Switching harmonics generated
by fixed-frequency operation are consistent and easily fil-
tered. Efficiency is enhanced under light loading (< 30mA
typ), by assuming an Idle Mode™ during which the con-
verter switches only as needed to service the load.
Internal n-channel synchronous rectifiers eliminate the
need for external Schottky diodes and improve efficien-
cy. The synchronous rectifier turns on during the sec-
ond half of each cycle (off-time). During this time, the
voltage across the inductor is reversed, and the induc-
tor current falls. In normal operation (not forced PWM),
the synchronous rectifier turns off at the end of the
cycle (at which time another on-time begins) or when
the inductor current approaches zero.
If the inductor current does not rise sufficiently to sup-
ply the load during the on-time, the switch remains on,
allowing operation up to 100% duty cycle. This allows
the output voltage to maintain regulation while the input
voltage approaches the regulation voltage. Dropout
voltage is approximately 180mV for an 800mA load on
V1 and 220mV for an 800mA load on V2. During
dropout, the high-side p-channel MOSFET turns on,
and the controller enters a low-current-consumption
mode. The device remains in this mode until the regula-
tor channel is no longer in dropout.
In addition to the high-efficiency step-down converters,
V1 and V2 can also be supplied with low-quiescent cur-
rent, low-dropout (LDO) linear regulators that can be
used in sleep mode or at any time when the load current
is very low. The sleep LDOs can source up to 35mA. To
enable the sleep LDOs, drive SLP low. When SLP is high,
the switching step-down converters are active. The out-
put voltage of the sleep LDOs is set to be the same as
the switching step-down converters as described in the
Setting the Output Voltages section. SLPIN is the input to
the V1 and V2 sleep LDOs and must connect to IN.
100% Duty-Cycle Operation
Synchronous Rectification
Sleep LDOs