A S 134 6- 4 9
Du al St ep- Down C on ver t e r w ith B att ery Mon ito r i ng
1 General Description
The AS1346, AS1347, AS1348, AS1349 family is a high-efficiency,
constant-frequency dual buck converter available with fixed voltage
versions. The device provides two independent DC/DC Converters
with output currents between 0.5A and 1.2A. The wide input voltage
range (2.7V to 5.5V), automatic powersave mode and minimal
external component requirements make the AS134x family perfect
for SSD and many other battery-powered applications.
In shutdown mode the typical supply current decreases to
≤1μA.
The highly efficient duty cycle (100%) provides low dropout
operation, prolonging battery life in portable systems.
An internal synchronous switching scheme increases efficiency and
eliminates the need for an external Schottky diode. The fixed
switching frequency (2.0MHz) allows the use of small surface mount
inductors.
The integrated monitoring function can be configured that either the
output voltage (Power Okay function ) or the input voltage (Battery
Monitoring Function) can be supervised.
Table 1. Available Products
Devices
AS1346
AS1347
AS1348
AS1349
I
OUT1
1.2A
0.5A
0.5A
1.2A
I
OUT2
0.5A
0.5A
0.95A
1.2A
2 Key Features
High Efficiency: Up to 95%
Output Current:
see Table 1
Input Voltage Range: 2.7V to 5.5V
Output Voltage Range: 1.2V to 3.6V (available in 100mV steps)
Constant Frequency Operation: 2.0MHz
180º Out of Phase Operation
Low Battery Detection
Low Dropout Operation: 100% Duty Cycle
Shutdown Mode Supply Current:
1μA
No Schottky Diode Required
Output Disconnect in Shutdown
Non standard variants available within two weeks
12-Pin TDFN 3x3mm Package
3 Applications
The device is ideal for SSD applications, mobile communication
devices, laptops and PDAs, ultra-low-power systems, threshold
detectors/discriminators, telemetry and remote systems, medical
instruments, or any other space-limited application with low power-
consumption requirements.
The AS1346-49 is available in a 12-Pin TDFN 3x3mm package.
Figure 1. AS1346 - Typical Application Diagram with POK Function
V
IN
2.7V to 5.5V
L1 = 3.3μH
C
IN
PVIN
PVIN
VDD
EN1
EN2
LBI
PGND
SW1
V
OUT1
3.3V 1200mA
C
OUT1
L2 = 3.3μH
C
OUT2
AS1346
FB1
SW2
FB2
LBO
AGND
V
OUT2
1.8V 500mA
POK Function
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Revision 1.10
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AS1346-49
Datasheet - P i n A s s i g n m e n t s
4 Pin Assignments
Figure 2. Pin Assignments (Top View)
SW1 1
PVIN 2
EN1 3
FB1 4
EN2 5
LBO 6
13
12 SW2
11 PVIN
10 VDD
9
8
7
FB2
AGND
LBI
AS1346
4.1 Pin Descriptions
Table 2. Pin Descriptions
Pin Number
1
2, 11
3
4
5
Pin Name
SW1
PVIN
EN1
FB1
EN2
Description
Switch Node1 Connection to Inductor. This pin connects to the drains of the internal main and
synchronous power MOSFET switches.
Power Supply Connector. This pin must be closely decoupled to PGND with a
4.7μF ceramic
capacitor.
Enable1 Input. Driving this pin above 1.2V enables V
OUT1
. Driving this pin below 0.5V puts the device in
shutdown mode. In shutdown mode all functions are disabled, drawing
1μA
supply current.
This pin should not be left floating.
Feedback Pin 1. Feedback input to the error amplifier, connect this pin to V
OUT1
. The output can be
factory set from 1.2V to 3.6V. For further information
see Ordering Information on page 15.
Enable2 Input. Driving this pin above 1.2V enables V
OUT2
. Driving this pin below 0.5V puts the device in
shutdown mode. In shutdown mode all functions are disabled, drawing
1μA
supply current.
This pin should not be left floating.
Low Battery Comperator Output. This open-drain output is low when:
- the voltage on LBI is higher than 1.2V or
- LBI is connected to GND and V
OUT1
is below 92.5% of its nominal value.
Low Battery Comperator Input. 1.2V Threshold. May not be left floating. If connected to GND, LBO is
working as Output Power Okay for V
OUT1
.
Analog Ground.
Feedback 2 Pin. Feedback input to the error amplifier, connect this pin to V
OUT2
. The output can be
factory set from 1.2V to 3.6V. For further information
see Ordering Information on page 15.
Supply Connector. Connect this pin to PVIN
Switch Node2 Connection to Inductor. This pin connects to the drains of the internal main and
synchronous power MOSFET switches.
Exposed Pad. The exposed pad must be connected to AGND. Ensure a good electrical connection to the
PCB to achieve optimal thermal performance.
6
7
8
9
10
12
13
LBO
LBI
AGND
FB2
VDD
SW2
PGND
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Revision 1.10
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AS1346-49
Datasheet - A b s o l u t e M a x i m u m R a t i n g s
5 Absolute Maximum Ratings
Stresses beyond those listed in
Table 3
may cause permanent damage to the device. These are stress ratings only, and functional operation of
the device at these or any other conditions beyond those indicated in
Electrical Characteristics on page 4
is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect device reliability.
Table 3. Absolute Maximum Ratings
Parameter
Electrical Parameters
VDD, PVIN to AGND
PGND to AGND
EN, FB
SW
PVIN to VDD
Electrostatic Discharge
Human Body Model
Temperature Ranges and Storage Conditions
Junction Temperature (T
J-MAX
)
Storage Temperature Range
-55
+150
+150
ºC
ºC
The reflow peak soldering temperature (body
temperature) specified is in accordance with IPC/
JEDEC J-STD-020 “Moisture/Reflow Sensitivity
Classification for Non-Hermetic Solid State
Surface Mount Devices”.
The lead finish for Pb-free leaded packages is
matte tin (100% Sn).
Represents a max. floor life time of unlimited
1
kV
Norm: MIL 883 E method 3015
-0.3
-0.3
AGND - 0.3
PGND - 0.3
-0.3
+7.0
+0.3
VDD + 0.3
PVIN + 0.3
+0.3
V
V
V
V
V
7.0V max
Min
Max
Units
Notes
Package Body Temperature
+260
ºC
Humidity non-condensing
Moisture Sensitive Level
5
1
85
%
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AS1346-49
Datasheet - E l e c t r i c a l C h a r a c t e r i s t i c s
6 Electrical Characteristics
PVIN = VDD = EN = 5V, unless otherwise noted. Typical values are at T
A
=25°C. All limits are guaranteed. The parameters with min and max
values are guaranteed with production tests or SQC (Statistical Quality Control) methods.
Table 4. Electrical Characteristics
Symbol
T
A
T
J
V
IN
V
OUT
I
Q
Parameter
Operating Temperature Range
Operating Junction Temperature Range
Input Voltage Range
Output Voltage Range
Quiescent Supply Current
1
Conditions
Min
-40
-40
Typ
Max
+85
+125
5.5
3.6
Units
°C
°C
V
V
mA
mA
mA
mA
mA
mA
mA
mA
mA
V
IN
V
OUT
(see Table 8 on page 15)
2.7
1.2
2
2.8
AS1346, V
OUT1
= 3.3V
I
OUT1
Output current 1
AS1347
AS1348
AS1349
AS1346, V
OUT2
= 1.8V
I
OUT2
Output current 2
AS1347
AS1348
AS1349
I
SHDN
Regulation
V
OUT1
V
OUT2
Output Voltage 1
Accuracy
Output Voltage 2
Accuracy
Line Transient Response
Load Transient Response
f
OSC
t
ON
DC-DC Switches
I
SW1
I
SW2
R
DSON1(P)
R
DSON1(N)
SW1 Current Limit
SW2 Current Limit
Pin-Pin Resistance for PMOS1
Pin-Pin Resistance for NMOS1
AS1346
AS1346
V
DD
= 5.0V, I
SW
= 200mA
V
DD
= 5.0V, I
SW
= 200mA
Oscillator frequency
Turn on time
V
IN
= 4.5V to 5.5V, I
OUT1
= 500mA,
V
OUT1
= 3.3V, EN2 = 0V
V
IN
= 5V, I
OUT1
= 0 to 500mA, V
OUT1
= 3.3V, EN2 = 0V
1.8
AS1346, I
OUT2
= 100mA
1.764
AS1346, I
OUT1
= 100mA
3.234
Shutdown Current
1200
500
500
1200
500
500
950
1200
0.1
3.3
+2
1.8
+2
50
50
2
350
1.55
800
150
250
2.2
1.836
1
3.366
μA
V
%
V
%
mVpk
mVpk
MHz
μs
A
mA
m
m
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Revision 1.10
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AS1346-49
Datasheet - E l e c t r i c a l C h a r a c t e r i s t i c s
Table 4. Electrical Characteristics
Symbol
R
DSON2(P)
R
DSON2(N)
Enable
V
IH,EN
V
IH,EN
Low Battery & Power-OK
V
LBI
LBI Threshold
LBI Hysteresis
LBI Leakage Current
LBO Voltage Low
2
Parameter
Pin-Pin Resistance for PMOS2
Pin-Pin Resistance for NMOS2
Logic high input threshold
Logic low input threshold
Conditions
V
DD
= 5.0V, I
SW
= 200mA
V
DD
= 5.0V, I
SW
= 200mA
Min
Typ
150
250
Max
Units
m
m
V
1.2
0.5V
Falling Edge
LBI = 5V, T
A
= 25°C
I
LBO
= 0.1mA
LBO = 5V, T
A
= 25°C
LBI = 0V, Falling Edge
85
1.16
1.2
10
1
0.05
1
88
90
1.24
V
V
mV
nA
V
nA
%
LBO Leakage Current
Power-OK Threshold
1. The dynamic supply current is higher due to the gate charge delivered at the switching frequency. The Quiescent Current is measured
while the DC-DC Converter is not switching.
2. LBO goes low in startup mode as well as during normal operation if,
1) The voltage at the LBI pin is higher than LBI threshold.
2) The voltage at the LBI pin is below 0.1V (connected to GND) and V
OUT1
is below 92.5% of its nominal value.
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