LTC3589HUJ#PBF Linear Technology, LTC3589HUJ#PBF Datasheet - Page 21

• 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
Table 5. Step-Down Switching Regulator 1 Command Register
Settings
COMMAND
REGISTER[BIT]
SCR1[1-0]
OVEN[0]
SCR2[0]
VCCR[1]
VCCR[0]
VRRCR[1-0]
B1DTV1[5]
B1DTV1[4-0]
B1DTV2[4-0]
B1DTV2[5]
B1DTV2[6]
B1DTV2[7]
* Denotes Default Power-On Value
Soft-Start
Soft-start is accomplished by gradually increasing the
input reference voltage on each step-down switching
regulator from 0V to the dynamic reference DAC output
level at a rate of 0.8V/ms. This allows each output to
rise slowly, helping minimize inrush current required to
charge up the regulator output capacitor. A soft-start cycle
occurs whenever a regulator is enabled either initially or
while powering up following a fault condition. A soft-start
cycle is not triggered by a change of operating modes or
a dynamic voltage slew. During soft-start the converter is
forced to pulse-skipping mode regardless of the settings
in the SCR1 command register.
11001*
11001*
VALUE
00*
01
10
00
01
10
11*
0*
1
0*
1
0*
1
1
0*
1
0*
1
0*
1
0*
1
SETTING
Pulse-Skipping Mode
Burst Mode Operation
Forced Continuous Mode
Disable
Enable
Wait for Output Below 300mV Before Enable
Enable Immediately
Select Register B1DTV1 (V1) Reference
Select Register B1DTV2 (V2) Reference
Initiate Dynamic Voltage Slew
Reference Slew Rate = 0.88mV/μs
Reference Slew Rate = 1.75mV/μs
Reference Slew Rate = 3.5mV/μs
Reference Slew Rate = 7mV/μs
Force PGOOD Low When Slewing
Normal PGOOD Operation When Slewing
DAC Dynamic Target Voltage V1
DAC Dynamic Target Voltage V2
2.25MHz Switching Frequency
1.125MHz Switching Frequency
Switch on Clock Phase 1
Switch on Clock Phase 2
Shutdown Regulator 1 Normally
Keep Regulator 1 Alive
Table 6. Step-Down Switching Regulator 2 Command Register
Settings
COMMAND
REGISTER[BIT]
SCR1[3-2]
OVEN[1]
SCR2[1]
VCCR[3]
VCCR[2]
VRRCR[3-2]
B2DTV1[5]
B2DTV1[4-0]
B2DTV2[4-0]
B2DTV2[5]
B2DTV2[6]
B2DTV2[7]
* Denotes Default Power-On Value
Switching EMI Control
The step-down switching regulators contain new pat-
ent pending circuitry to limit the edge rate of the switch
nodes SW1, SW2, and SW3. This new circuitry controls
the transition of the switch node over a period of a few
nanoseconds, signifi cantly reducing radiated EMI and
conducted supply noise while maintaining high effi ciency.
Since slowing the slew rate of the switch nodes causes
effi ciency loss, the slew rate of the step-down switching
regulators is adjustable using the I
B1DTV1 bits 6 and 7. Optimize effi ciency or EMI as neces-
sary with four different slew rate settings. The power-on
default is the fastest slew rate, highest effi ciency setting.
11001*
11001*
VALUE
LTC3589/LTC3589-1
00*
01
10
00
01
10
11*
0*
1
0*
1
0*
1
1
0*
1
0*
1
0*
1
0*
1
SETTING
Pulse-Skipping Mode
Burst Mode Operation
Forced Continuous Mode
Disable
Enable
Wait for Output Below 300mV Before Enable
Enable immediately
Select Register B2DTV1 (V1) Reference
Select Register B2DTV2 (V2) Reference
Initiate Dynamic Voltage Slew
Reference Slew Rate = 0.88mV/μs
Reference Slew Rate = 1.75mV/μs
Reference Slew Rate = 3.5mV/μs
Reference Slew Rate = 7mV/μs
Force PGOOD Low When Slewing
Normal PGOOD Operation When Slewing
DAC Dynamic Target Voltage V1
DAC Dynamic Target Voltage V2
2.25MHz Switching Frequency
1.125MHz Switching Frequency
Switch on Clock Phase 1
Switch on Clock Phase 2
Shutdown Regulator 2 Normally
Keep Regulator 2 Alive
2
C command register
21
3589fc