ltc3523-ltc3523-2 Linear Technology Corporation, ltc3523-ltc3523-2 Datasheet - Page 5

• Manufacturer Part Number: ltc3523-ltc3523-2
• Description: Synchronous 600ma Step-up And 400ma Step-down Dc/dc Converters
• Manufacturer: Linear Technology Corporation

TYPICAL PERFORMANCE CHARACTERISTICS
PIN FUNCTIONS
FB1 (Pin 1): Step-Up Converter Feedback Input to the Er-
ror Amplifi er. Connect resistor divider tap to this pin. The
output voltage can be adjusted from 1.8V to 5.25V by:
See Block Diagram.
V
pin can be connected to a different supply than V
pin must be connected to a valid supply voltage.
IN1
0.7
1.3
1.2
1.1
1.0
0.9
0.8
0.6
0.5
V
–45
(Pin 2): Step-Up Converter Power Voltage Input. This
OUT(STEP-UP)
Normalized R
Temperature
–25
PMOS
–5
TEMPERATURE (°C)
NMOS
300
500
450
400
350
250
200
150
100
50
DS(ON)
0
=
15
Maximum I
Step-Up Converter
1
1 2
V
.
OUT
vs
35
V
= 2.5V
•
2
⎛
⎝ ⎜
55
INPUT VOLTAGE (V)
1
OUT
+
V
OUT
R
3523 G10
R
75
vs V
2
= 3.3V
1
3
⎞
⎠ ⎟
IN
for the
4
V
500
450
400
350
300
250
200
150
100
OUT
50
0
1.5
Step-Up No-Load Input Current
vs V
3523 G13
= 5V
V
IN2
5
IN
OUT
2
. This
= 2.8V
V
2.5
OUT
V
INPUT VOLTAGE (V)
OUT
= 3.3V
= 5V
3
PGOOD1 (Pin 3): Step-Up Converter Power Good Com-
parator Output. This open-drain output is pulled low when
V
V
and Drain of the Internal Synchronous Rectifi er MOSFET.
Driver bias is derived from V
V
and wide as possible.
3.5
FB1
OUT
OUT
< –9% of its regulation voltage.
(Pin 4): Step-Up Converter Output Voltage Sense Input
4
to the output fi lter capacitor(s) should be as short
350
300
200
150
450
400
250
100
4.5
50
0
(T
3523 G11
1
Maximum I
Step-Down Converter
A
= 25°C unless otherwise noted)
V
5
OUT
1.5
LTC3523/LTC3523-2
= 1.2V
V
OUT
2
50mV/DIV
20mV/DIV
V
V
INPUT VOLTAGE (V)
OUT_BST
OUT_BCK
OUT
= 1.8V
2V/DIV
2.5
MODE
vs V
3
Mode Transition Response
V
V
V
I
I
C
L1 = L2 = 4.7μH
OUT1
OUT2
OUT1
OUT2
IN
OUT1
IN
OUT
= 2.4V
3.5
for the
= 20mA
= 25mA
V
= 3.3V
= 1.2V
= C
OUT
. PCB trace length from
OUT2
4
= 2.5V
= 10μF
4.5
3523 G14
200μs/DIV
5
5
3523 G12
3523f