LTC3589HUJ#PBF Linear Technology, LTC3589HUJ#PBF Datasheet - Page 17

• 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
The LTC3589/LTC3589-1 has fl exible options for enabling
and sequencing the regulator enables. The regulators are
enabled using input pins or the I
power-on sequence tie the enable of the fi rst regulator to be
powered up to the WAKE pin. Connect the fi rst regulators
output to the enable pin of the second regulator, and so on.
One or more regulators may be started in any sequence.
Each enable pin has a 200μs (typical) delay between the pin
and the internal enable of the regulator. When the system
controllers are satisfi ed that power rails are up, the con-
troller must drive PWR_ON HIGH to keep WAKE active. To
ensure correct start-up sequencing, the regulators outputs
are monitored by voltage comparators which require each
output to discharge below 300mV before re-enabling. A
software control command register function is available
which sets the regulators to effectively ignore their enable
pins but respond to I
enables software-only control of any combination of pin-
strapped regulators and is useful for implementing system
power saving modes. Keep-alive mode exempts selected
regulators from turning off during normal shutdown. In
keep-alive mode, the LTC3589/LTC3589-1 powers down
normally and is ready for the next start-up sequence, but
selected regulators are kept on to power memory or other
functions during system standby modes.
The LTC3589/LTC3589-1 will shut down all regulators
and pull down the WAKE pin under high temperature, V
undervoltage, and extended low regulator output voltage
conditions. Status of a hard shutdown is reported by the
IRQ status pin and the IRQSTAT status register.
The I
13 command registers for controlling each of the regula-
tors, one read-only register for monitoring each regulators
power good status, one read-only register for reading
the cause of an IRQ event, and one clear IRQ command
register. The LTC3589/LTC3589-1 I
addressing of any register.
2
C serial port on the LTC3589/LTC3589-1 contains
2
C register enables. This function
2
C serial port. To defi ne a
2
C supports random
IN
LTC3589 TO LTC3589-1 FUNCTIONAL COMPARISON
Table 1. summarizes the functional differences between
the LTC3589 and the LTC3589-1.
Table 1. LTC3589 and LTC3589-1 Functional Differences
Power-On Inhibit Enable
Delay
Buck2 Current Output
Buck3 Current Output
PGOOD Fault Timeout
PWR_ON to WAKE Delay
LDO3 V
LDO4 V
* Indicates Default V
Default LDO4 Enable
Details of the operation of the LTC3589 and LTC3589-1
are found in the following sections.
ALWAYS-ON LDO
The LTC3589/LTC3589-1 includes a low quiescent current
low dropout regulator that remains powered whenever a
valid supply is present on V
remain active until V
is below the 2.5V undervoltage threshold in effect for the
rest of the LTC3589/LTC3589-1 circuits. The always-on
LDO is used to provide power to a standby microcon-
troller, real-time clock, or other keep-alive circuits. The
LDO is guaranteed to support a 25mA load. A 1μF low
impedance ceramic bypass capacitor from LDO1_STBY
to GND is required for compensation. A power good
monitor pulls RSTO LOW for a minimum of 14ms (typical)
whenever LDO1_STBY is 8% below its regulation target.
An LDO1_STBY undervoltage condition is reported in the
PGOOD status register. The output voltage of LDO1 is set
with a resistor divider connected from LDO1_STBY to the
feedback pin LDO1_FB, as shown in Figure 1.
Typical values for R1 are in the range of 40k to 1M.
V
LDO_STBY
OUT
OUT
= 0.8 • 1+
OUT
LTC3589/LTC3589-1
IN
LTC3589
1 second
1A
1A
Enabled by Default.
I
50ms
1.8V
1.8V, 2.5V, 2.8V*,
3.3V
LDO34_EN Pin
2
C Disable.
drops below 2.0V (typical). This
R2
R1
IN
. The always-on LDO will
(V)
LTC3589-1
<2ms
1.2A
1.2A
Disabled by default.
I
2ms
2.8V
1.2V*, 1.8V, 2.5V,
3.2V
I
2
2
C Enable.
C
17
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