LTC3589HUJ#PBF Linear Technology, LTC3589HUJ#PBF Datasheet - Page 16

• Manufacturer Part Number: LTC3589HUJ#PBF
• Description: IC DC/DC CONV 8-OUTPUT 40QFN
• Manufacturer: Linear Technology

Specifications of LTC3589HUJ#PBF

• Applications: Handheld/Mobile Devices
• Current - Supply: 8µA
• Voltage - Supply: 2.7 V ~ 5.5 V
• Operating Temperature: -40°C ~ 150°C
• Mounting Type: Surface Mount
• Package / Case: *
• Primary Input Voltage: 5.5V
• No. Of Outputs: 8
• Output Voltage: 5V
• Output Current: 1.6A
• No. Of Pins: 40
• Operating Temperature Range: -40°C To +150°C
• Msl: MSL 1 - Unlimited
• No. Of Ldo Regulators: 3
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

OPERATION
LTC3589/LTC3589-1
INTRODUCTION
The LTC3589/LTC3589-1 is a complete power manage-
ment solution for portable microprocessors and periph-
eral devices. It generates a total of eight voltage rails for
supplying power to the processor core, SDRAM, system
memory, PC cards, always-on real-time clock and HDD
functions. Supplying the voltage rails are an always-on
low quiescent current 25mA LDO, one 1.6A and two 1A
(1.2A for LTC3589-1) step-down regulators, a 1.2A buck-
boost regulator, and three 250mA low dropout regulators.
Supporting the multiple regulators is a highly confi gurable
power-on sequencing capability, dynamic voltage slewing
DAC output voltage control, a pushbutton interface con-
troller, regulator control via an I
status and interrupt outputs.
The LTC3589/LTC3589-1 operates over an input supply
range of 2.7V to 5.5V. The input supplies for the 250mA
LDO regulators may operate as low as 1.7V to limit power
loss at low output voltages.
The always-on LDO1 provides a resistor programmable
output voltage as low as 0.8V and is capable of supplying
25mA. With only the always-on LDO active the LTC3589/
LTC3589-1 draws just 8μA (typical). Always-on LDO1 will
continue to operate with V
to maintain memory and RTC function as long as possible.
Each of the 250mA LDO regulators has unique output
voltage confi gurations. LDO3 has a fi xed 1.8V (2.8V for
LTC3589-1) output. LDO4 has four output levels selectable
via the I
2.8V, and 3.3V. (1.2V, 1.8V, 2.5V, 3.2V for LTC3589-1) LDO2
has a dynamically slewing DAC set point reference and
an external feedback pin to set the output voltage range
with a resistive divider. Each LDO draws 60μA (typical)
quiescent current.
The LTC3589 includes three internally compensated con-
stant frequency current mode step-down switching regu-
lators two capable of supplying 1A of output current and
one capable of supplying 1.6A. The LTC3589-1 step-down
regulators can supply 1.2A, 1.2A, and 1.6A. Step-down
regulator switching frequencies of 2.25MHz or 1.125MHz
are independently selected for each step-down regulator
using the I
16
2
C interface. Its possible outputs are 1.8V, 2.5V,
2
C command registers. The power-on default
IN
levels as low as 2.0V (typical)
2
C interface, and extensive
frequency is 2.25MHz. Each of the step-down regulators
have dynamically slewing DAC input references and external
feedback pins to set output voltage range. The step-down
regulators three operating modes, pulse-skipping, burst,
or forced continuous, are set using the I
pulse-skipping mode the regulator will support 100%
duty cycle. For best effi ciency at low output loads select
Burst Mode operation. Forced continuous mode minimizes
output voltage ripple at light loads.
The 4-switch buck-boost DC/DC voltage mode converter
generates a user-programmable output voltage rail from
1.8V to 5V. Utilizing a proprietary switching algorithm,
the buck-boost converter maintains high effi ciency and
low noise operation with input voltages that are above,
below or equal to the required output rail. The buck-boost
error amplifi er uses a fi xed 0.8V reference and the output
voltage is set by an external resistor divider. Burst Mode
operation is enabled through the I
external compensation components are required for the
buck-boost converter.
The reference inputs for the three step-down regulators
and LDO2 are 5-bit D to A converters with up-down ramp-
ing at selectable slew rates. The slew endpoint voltages
and select bits are stored in I
A select bit in the I
register to use for each target voltage. Variable reference
slew rates from 0.88mV/μs to 7mV/μs are selectable in
the I
voltage, voltage select, and slew rate control registers.
The LTC3589/LTC3589-1 is equipped with a pushbutton
control circuit that will activate the WAKE output, indicate
pushbutton status via the PBSTAT pin, and initiate a hard
reset shutdown of the regulators. Grounding the ON pin
with the pushbutton for 400ms will force the WAKE pin
to release HIGH. The WAKE pin output can be tied to the
enable pin of the fi rst regulator in a power-on sequence.
Once in the power-on state, subsequent pushes of the but-
ton longer than 50ms are mirrored by the PBSTAT output.
Holding ON LOW for fi ve seconds disables all the regula-
tors, pulls down the WAKE pin, and pulls down RSTO for
one second to indicate to the processor that a hard reset
occurred. All regulator enables and pushbutton inputs are
inhibited for one second following the hard reset.
2
C register. Each of the four DACs has independent
2
C command registers chooses which
2
C registers for each DAC.
2
C control registers. No
2
C interface. In
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