AIC1577
External NMOS Step-Down PWM Controller
DESCRIPTION
The AIC1577 is a current mode switching
regulator controller that drives external N-
channel
power
MOSFET
using
a
fixed
frequency architecure. It uses external divider
to adjust output voltage from 0.8V to 20V with
excellent line and load regulation. A maximum
high duty cycle limit of 95% provides low
dropout operation which extends operating
time in battery-operated systems.
Switching frequency up to 500KHz are
achievable thus allowing smaller sized filter
components. The operating current level is
user-programmable via an external current
sense
resistor.
It
also
provide
output
FEATURES
N-Channel MOSFET Drive
Operating Input Voltage from 4.5V to 24V
Wide Ouput Range : 0.8V to 20V
±1.5%
0.8V Reference
Low Dropout Operation : 95% Duty Cycle
500KHz Fixed Constant Frequency
Low Standby Current, I
Q
Typically 720µA
Logic-Control Micropower Shutdown
Output Overvoltage Protection
Internal Diode for Bootstrapped Gate Drive
Current Mode Operation for Excellent Line and
Load Transient Response
Available in an 8-Lead SO and MSOP Package
APPLICATIONS
LCD Monitor
Palmtop Computers, PDAs
Wireless Modems
On-Card Switching Regulators
DC Power Distribution Systems
overvoltage protection under fault conditions.
A multifunction pin (I
TH
/RUN) allows external
compensation
for
optimum
load
step
response plus shutdown. Soft start can also
be implemented with this pin to properly
sequence supplies. Package available are in
SOP-8 and MSOP-8 for SMD.
Analog Integrations Corporation
Si-Soft Research Center
3A1, No.1, Li-Hsin Rd. I , Science Park , Hsinchu 300, Taiwan , R.O.C.
TEL: 886-3-5772500
FAX: 886-3-5772510
www.analog.com.tw
DS-1577G-01 121808
1
AIC1577
TYPICAL APPLICATION CIRCUIT
1
2
C5
330pF
R3
24k
3
4
8
7
6
5
C3
0.1µF
1000pF
C1
C2
0.1µF
R
S
33m
+
V
IN
6V~24V
C
IN1
22µF
+
CS
VIN
ITH/RUN BOOST
FB
DRI
C
IN2
22µF
SW
GND
AIC1577
M1
FDS6694
D1
SL43
L1
10µH
V
OUT
3.3V 3A
C
OUT
220µF
C6
2.2µF
C4
R1
20k
1nF
R2 62k
C
IN1
, C
IN2
: OS-CON 22µF/30V Electrolytic capacitors
M1: FAIRCHILD FDS6694 N-MOSFET
D1: GS SL43
L1: TDK SLF12555T-100M3R4
C
OUT
: HER-MEI 220µF /16V Electrolytic capacitor
C6: TAIYO YUDEN LMK212BJ225KG-T Ceramic capacitor
ORDERING INFORMATION
AIC1577-XXXX
PACKING TYPE
TB: TUBE
TR: TAPING & REEL
PACKAGING TYPE
S: SOP-8
O: MSOP-8
C: Commercial
P: Lead Free Commercial
G: Green Package
Example: AIC1577COTR
in MSOP-8 Package & Taping &
Reel Packing Type
AIC1577POTR
in MSOP-8 Lead Free Package &
Taping & Reel Packing Type
PIN CONFIGURATION
TOP VIEW
CS 1
I
TH
/RUN 2
FB 3
GND
4
8
7
6
5
VIN
BOOST
DRI
SW
2
AIC1577
ABSOLUTE MAXIMUM RATINGS
Supply Voltage (VIN)
Drive Supply Voltage (BOOST)
Switch Voltage (SW)
Differential Boost Voltage (BOOST to SW )
I
TH
/RUN,VFB Voltages
Peak Drive Output Current < 10µS (DRI )
Operating Temperature Range
Junction Temperatrue
Storage Temperature Range
Lead Temperature (Soldering. 10 sec)
Thermal Resistance Junction to Case
Thermal Resistance Junction to Ambient
(Assume no ambient airflow, no heatsink)
SOP-8
MSOP-8
SOP-8
MSOP-8
25V
32V
25V
8V
7V
2A
-40°C ~ 85°C
125°C
-65°C ~ 150°C
260°C
40°C/W
75°C/W
160°C/W
180°C/W
Absolute Maximum Ratings are those values beyond which the life of a device may be Impaired.
TEST CIRCUIT
Refer to Typical Application Circuit.
3
AIC1577
ELECTRICAL CHARACTERISTICS
(T
A
=25°C, V
IN
=15V, unless otherwise noted.) (Note1)
PARAMETER
Input Voltage
Input Supply Current
Feedback Voltage
∆Output
Overvoltage Lockout
Reference Voltage Line
Regulation
Output Voltage Load
Regulation
Run Threshold
Maximum Current Sense
Threshold
Oscillator Frequency
DRI Rise Time
DRI Fall Time
BOOST Voltage
Maximum Duty Cycle
Soft Start Time
Run Current Source
Run Pullup Current
V
ITH/RUN
=0V, V
FB
=0V
V
ITH/RUN
=1V
C
LOAD
= 3000
P
F
C
LOAD
= 3000
P
F
V
IN
=8V, I
BOOST
=5mA, SW=0V
4.9
90
5
1.0
100
V
FB
=0.72V
V
FB
connect to Vout,
∆V
OVL
=V
OVL
-
V
FB
V
IN
= 4.5V to 20 V
I
TH
Sinking 5µA
I
TH
Sourcing 5µA
0.6
125
450
Normal Mode (Note 2)
Shutdown Mode, V
ITH/RUN
=0V
0.788
20
TEST CONDITIONS
MIN.
4.5
TYP.
MAX.
24
UNIT
V
µA
µA
V
mV
%/V
720
16
0.8
55
0.002
0.7
-0.4
0.8
150
500
50
50
5.3
94
7.5
2.3
190
900
20
0.812
90
0.015
1.1
-0.8
0.9
175
550
75
75
5.7
%
V
mV
KHz
nS
nS
V
%
mS
4.0
250
µA
µA
Note 1:
Specifications are production tested at TA=25°C. Specifications over the -40°C to 85°C operating
temperature range are assured by design, characterization and correlation with Statistical Quality
Controls (SQC).
Note 2:
Dynamic supply current is higher due to the gate charge being delivered at the switching frequency.
4
AIC1577
TYPICAL PERFORMANCE CHARACTERISTICS
100
100
V
OUT
=3.3V
95
V
OUT
=5V
V
IN
=6V
Efficiency (%)
V
IN
=12V
V
IN
=19V
95
90
85
80
75
70
V
IN
=6V
V
IN
=12V
V
IN
=19V
Efficiency (%)
90
85
80
75
70
Load Current (mA)
Fig. 1 Efficiency vs Load Current (V
OUT
=3.3V)
100
1
10
100
1000
10000
1
10
100
1000
10000
Load Current (mA)
Fig. 2 Efficiency vs Load Current (V
OUT
=5.0V)
100
95
V
OUT
=3.3V
Efficiency (%)
95
90
V
OUT
=5V
Efficiency (%)
90
85
80
I
LOAD
=1A
85
I
LOAD
=1A
I
LOAD
=0.1A
80
75
I
LOAD
=0.1A
A
0
5
10
15
20
25
30
75
70
70
0
5
10
15
20
25
30
Input Voltage (V)
Fig. 3 Efficiency vs Input Voltage
900
800
7
Input Voltage (V)
Fig. 4 Efficiency vs Input Voltage
Normal Mode
Boost Voltage (V)
6
5
4
3
2
1
0
Supply Current (µA)
700
600
500
V
CC
=15V
V
CC
=5V
40
20
0
0
5
10
15
20
25
30
Shutdown
V
PHASE
=0V
0
5
10
15
20
Input Voltage (V)
Fig. 5 Supply Current vs Input Voltage
Boost Load Current (mA)
Fig. 6 Boost Load Regulation
5
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