LTC3890EGN-1#TRPBF Linear Technology, LTC3890EGN-1#TRPBF Datasheet - Page 20

• Manufacturer Part Number: LTC3890EGN-1#TRPBF
• Description: IC BUCK SYNC ADJ DUAL 28SSOP
• Manufacturer: Linear Technology
• Type: Step-Down (Buck)r

Specifications of LTC3890EGN-1#TRPBF

• Internal Switch(s): No
• Synchronous Rectifier: Yes
• Number Of Outputs: 2
• Voltage - Output: 0.8 ~ 24 V
• Frequency - Switching: 350kHz ~ 535kHz
• Voltage - Input: 4 ~ 60 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 28-SSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Output: -
• Power - Output: -

LTC3890-1
Alternatively, the TRACK/SS pin can be used to track two
(or more) supplies during start-up, as shown qualitatively
in Figures 7a and 7b. To do this, a resistor divider should
be connected from the master supply (V
SS pin of the slave supply (V
During start-up V
set by the resistor divider:
For coincident tracking (V
INTV
The LTC3890-1 features two separate internal P-channel
low dropout linear regulators (LDO) that supply power at
the INTV
pin depending on the connection of the EXTV
powers the gate drivers and much of the LTC3890-1’s
internal circuitry. The V
INTV
50mA and must be bypassed to ground with a minimum
of 4.7μF ceramic capacitor. No matter what type of bulk
capacitor is used, an additional 1μF ceramic capacitor
placed directly adjacent to the INTV
highly recommended. Good bypassing is needed to supply
the high transient currents required by the MOSFET gate
drivers and to prevent interaction between the channels.
High input voltage applications in which large MOSFETs
are being driven at high frequencies may cause the maxi-
mum junction temperature rating for the LTC3890-1 to be
exceeded. The INTV
gate charge current, may be supplied by either the V
LDO or the EXTV
APPLICATIONS INFORMATION
20
R
R
V
Figure 6. Using the TRACK/SS Pin to Program Soft-Start
A
B
V
OUT
CC
CC
X
= R
= R
to 5.1V. Each of these can supply a peak current of
Regulators
CC
=
TRACKA
TRACKB
pin from either the V
R
TRACKA
R
A
CC
OUT
LDO. When the voltage on the EXTV
CC
•
will track V
IN
current, which is dominated by the
C
R
SS
LDO and the EXTV
TRACKA
OUT
TRACK/SS
SGND
1/2 LTC3890-1
R
OUT
= V
A
IN
+ R
+ R
supply pin or the EXTV
), as shown in Figure 8.
X
38901 F06
X
CC
according to the ratio
during start-up):
TRACKB
B
and PGND IC pins is
X
) to the TRACK/
CC
CC
LDO regulate
pin. INTV
CC
CC
CC
IN
Figure 7. Two Different Modes of Output Voltage Tracking
Figure 8. Using the TRACK/SS Pin for Tracking
R
R
TRACKB
TRACKA
(7b) Ratiometric Tracking
(7a) Coincident Tracking
V
x
V
TIME
TIME
OUT
R
R
B
A
1/2 LTC3890-1
V
TRACK/SS
FB
38901 F07b
38901 F07a
38901 F08
V
V
V
V
X(MASTER)
OUT(SLAVE)
X(MASTER)
OUT(SLAVE)
38901fa