lt3580ems8e-trpbf Linear Technology Corporation, lt3580ems8e-trpbf Datasheet - Page 5

• Manufacturer Part Number: lt3580ems8e-trpbf
• Description: Boost/inverting Dc/dc Converter With 2a Switch, Soft-start, And Synchronization
• Manufacturer: Linear Technology Corporation

TYPICAL PERFORMANCE CHARACTERISTICS
PIN FUNCTIONS
FB (Pin 1): Positive and Negative Feedback Pin. For a
boost or inverting converter, tie a resistor from the FB pin
to V
VC (Pin 2): Error Amplifi er Output Pin. Tie external com-
pensation network to this pin.
V
SW (Pin 4): Switch Pin. This is the collector of the internal
NPN Power switch. Minimize the metal trace area connected
to this pin to minimize EMI.
SHDN (Pin 5): Shutdown Pin. In conjunction with the
UVLO (undervoltage lockout) circuit, this pin is used
to enable/disable the chip and restart the soft-start
sequence. Drive below 1.24V to disable the chip. Drive
above 1.38V to activate chip and restart the soft-start
sequence. Do not fl oat this pin.
IN
R
R
FB
FB
30
25
20
15
10
(Pin 3): Input Supply Pin. Must be locally bypassed.
OUT
5
0
=
=
SHDN Pin Current
0
(
(
according to the following equations:
V
V
83.3 • 10
83.3 • 10
OUT
100°C
OUT
0.5
SHDN VOLTAGE (V)
+ 5mV
1.215
6
6
20°C
1
)
–50°C
)
; Inverting Converter
; Boost or SEPIC Converter
1.5
3580 G10
2
300
250
200
150
100
50
0
0
SHDN Pin Current
5
10
SHDN VOLTAGE (V)
–50°C
15
100°C
RT (Pin 6): Timing Resistor Pin. Adjusts the switching
frequency. Place a resistor from this pin to ground to set
the frequency to a fi xed free running level. Do not fl oat
this pin.
SS (Pin 7): Soft-Start Pin. Place a soft-start capacitor here.
Upon start-up, the SS pin will be charged by a (nominally)
275k resistor to about 2.2V.
SYNC (Pin 8): To synchronize the switching frequency to
an outside clock, simply drive this pin with a clock. The
high voltage level of the clock needs to exceed 1.3V, and
the low level should be less 0.4V. Drive this pin to less than
0.4V to revert to the internal free running clock. See the
Applications Information section for more information.
Exposed Pad (Pin 9): Ground. Must be soldered directly
to local ground plane.
20°C
20
25
T
3580 G11
A
30
= 25°C unless otherwise specifi ed
1.32
1.20
1.40
1.38
1.36
1.34
1.30
1.28
1.26
1.24
1.22
–50
Active/Lockout Threshold
SHDN RISING
0
TEMPERATURE (°C)
SHDN FALLING
50
LT3580
100
3580 G12
3580fa
5