LTC3589HUJ#PBF Linear Technology, LTC3589HUJ#PBF Datasheet - Page 19

• 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
LDO Regulator 3
LDO3 is a fi xed 1.8V or 2.8V (LTC3589-1) output regula-
tor. LDO3 is enabled by driving pin EN_LDO34 high or by
writing command register OVEN[5] to 1.
Table 3 shows the I
to control LDO3.
Table 3. LDO 3 Command Register Settings
COMMAND
REGISTER[BIT]
OVEN[5]
SCR2[5]
* Denotes Default Power-On Value
LDO Regulator 4
LDO4 has four output voltage options that are controlled
by the contents of command register bits L2DTV2[6]
and L2DTV2[5]. When pin EN_LDO34 is low, LDO3 and
LDO4 are controlled by writing to command register bits
OVEN[5] and OVEN[6] respectively. By default, the LTC3589
pin EN_LDO34 enables and disables LDO3 and LDO4 si-
multaneously when command register bits OVEN[5] and
OVEN[6] are low. When command register bit L2DTV2[7] is
high, control of LDO4 is disconnected from pin EN_LDO34
and controlled by command register bit OVEN[6] regardless
of the status of EN_LDO34. The LTC3589-1 pin EN_LDO3
enables only LDO3. Control of LDO4 on the LTC3589-1 is
under I
register settings that control LDO4.
EN
MODE
5
2
C control only. Table 4 shows the I
Figure 3. Step-Down Switching Regulator
Application Circuit
CONTROL
PWM
DAC
VALUE
0*
1
0*
1
2
C command register settings used
SETTING
Disable
Enable
Wait for Output Below 300mV Before Enable
Enable Immediately
0.3625V
TO 0.75V
PV
IN
3589 F03
SW
FB
L1
C
FB
2
C command
R1
R2
C
OUT
Table 4. LTC3589 Command Register Settings
COMMAND
REGISTER[BIT]
OVEN[6]
SCR2[6]
L2DTV2[6-5]
L2DTV2[7]
LTC3589-1 Command Register Settings
OVEN[6]
SCR2[6]
L2DTV2[6-5]
L2DTV2[7]
* Denotes Default Power-On Value
STEP-DOWN SWITCHING REGULATORS
Output Voltage Programming
Each of the step-down converters uses a dynamically
slewing DAC output for its reference. The full-scale output
voltage is set by using a resistor divider connected from
the step-down switching regulator output to the feedback
pins (B1_FB, B2_FB, and B3_FB), as shown in Figure 3.
Set the output voltage of step-down switching regulators
using the following formula:
BxDTVx is the decimal value of the fi ve bit binary number
in the I
and BxDTV2 default to 11001 to output a reference voltage
of 0.675V. Typical values for R1 are in the range of 40k
to 1M. The capacitor C
feedback resistors and the input capacitance on the FB pin
and also helps to improve load step transient response.
V
OUT
2
C BxDTV1 or BxDTV2 command registers. BxDTV1
= 1+
VALUE
R2
R1
00*
01
10
11
00*
01
10
11
LTC3589/LTC3589-1
0*
1
0*
1
0*
1
0*
1
0*
1
0*
1
• (0.3625 + BxDTVx • 0.0125)(V)
SETTING
Disable
Enable
Wait for Output Below 300mV Before Enable
Enable Immediately
V
V
V
V
LDO4 Enable Controlled by EN_LDO34
LDO4 Enable Controlled by OVEN[6]
Disable
Enable
Wait for Output Below 300mV Before Enable
Enable Immediately
V
V
V
V
Unused
FB
LDO4
LDO4
LDO4
LDO4
LDO4
LDO4
LDO4
LDO4
cancels the pole created by the
= 2.8V
= 2.5V
= 1.8V
= 3.3V
= 1.2V
= 1.8V
= 2.5V
= 3.2V
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