lt3473a Linear Technology Corporation, lt3473a Datasheet - Page 5

• Manufacturer Part Number: lt3473a
• Description: Micropower 1a Boost Converter With Schottky And Output Disconnect
• Manufacturer: Linear Technology Corporation

PI FU CTIO S
CAP (Pin 1/Pin 1): Internal Output Voltage. This pin is the
Schottky cathode and disconnect PNP emitter. Connect
output capacitor here.
OUT (Pin 2/Pin 2): Output of Disconnect Circuit. Bypass
this pin with capacitor to ground.
CTRL (Pin 3/Pin 8): External Reference Pin. This pin sets
the FB voltage externally between 0V and 1.25V. Tie this
pin 1.5V or higher to use the internal 1.25V reference.
FB (Pin 4/Pin 7): Feedback Pin. Pin voltage is regulated to
1.25V if internal reference is used or to the CTRL pin
voltage if the CTRL pin voltage is between 0V and 1.25V.
Connect the feedback resistor divider to this pin. The
output voltage is regulated to:
PGOOD (Pin 5/Pin 9): Power Good Output. Open collector
logic output that starts to sink current when FB reaches
within 100mV of the reference voltage.
TYPICAL PERFOR A CE CHARACTERISTICS
U
1.4
1.2
1.0
0.8
0.6
0.4
0.2
V
0
OUT
0
Disconnect PNP Quiescent Current
=
5
U
V
10
REF
CAP VOLTAGE (V)
15
•
⎛
⎜
⎝
R
R
20
U
2
1
+
25
1
(LT3473/LT3473A)
⎞
⎟
⎠
30
W
35
3473 G13
U
40
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0
SHDN Voltage to Turn-On
Disconnect PNP
20
OUTPUT CURRENT (mA)
40
SHDN (Pin 6/Pin 10): Shutdown Pin. Connect to 1.4V or
higher to enable device; 0.2V or less to disable device. Also
functions as soft-start. Use RC filter as shown in Figure 4.
V
bypassed with a X5R or X7R type ceramic capacitor.
SW (Pin 8/Pin 12): Switch Pin. Connect inductor here.
Minimize the metal trace area connected to the pin to
minimize EMI.
Exposed Pad (Pin 9/Pin 13): Ground. Solder directly to
PCB ground plane through multiple vias under the pack-
age for optimum thermal performance.
LT3473A Only
NB1 (Pin 3): NPN1 Base.
NE1 (Pin 4): NPN1 Emitter.
NB2 (Pin 5): NPN2 Base.
NE2 (Pin 6): NPN2 Emitter.
IN
60
(Pin 7/Pin 11): Input Supply Pin. Must be locally
80
3473 G14
T
A
= 25°C unless otherwise noted.
100
1.00
0.90
0.85
0.80
0.70
0.50
0.95
0.75
0.65
0.60
0.55
–50
Auxiliary NPN V
LT3473/LT3473A
TEMPERATURE (°C)
0
I
E
I
= 100µA
BE
E
= 1mA
50
3473 G15
5
3473f
100