AME AME5138AEEVADJZ

AME, Inc.
Micropower Step-Up
DC/DC Converter
AME5138
n General Description
The AME5138 is a fixed off-time step-up DC/DC converter in a small 5-lead SOT-25 package.The AME5138
is ideal for LCD panels requiring low current and high efficiency as well as LED applications for cellular phone backlighting, PDAs,and other hand-held devices. The low 400ns
off-time allows the use of tiny external components.
AME5138 is designed to drive up to four white LEDs
in series with a constant current from a single Li-lon battery. To control LED brightness, the LED current can be
adjusted by applying a PWM (pulse width modulated)
signal with a frequency range of 100Hz to 50KHz to the
EN pin.
n Typical Application
L
10µH
V IN
2.5V-4.2V
5
1
V IN
CIN
4.7µF
Ceramic
Option for
4LEDs
D
SW
ILED
COUT
1µF
Ceramic
AME5138
>1.1V 4
3
EN
FB
GND
0V
R2
80Ω
2
* ILED =VFB/R2
n Features
Figure 1: Four White LEDs Application in Li-lon
Battery
l 0.7Ω internal switch
l Uses small surface mount components
l Adjustable output voltage up to 20V
l 2V to 5.5V input range
VIN
2.5V-4.2V
L
15µH
20V
10mA
D
l Input undervoltage lockout
l 0.01µA shutdown current
l Small 5-Lead SOT-25 package
l All AME's lead free Product Meet RoHS
Standard
5
1
VIN
CIN
4.7µF
Ceramic
4
R1
200K
SW
AME5138 FB
3
EN
GND
2
COUT
1µF
Ceramic
R2
13K
n Applications
l
White LED Back-Lighting
l
Hand-held Devices
l
Digital Cameras
l
Portable Applications
l
LCD Bias Power
Figure 2: Typical 20V Application
1
AME, Inc.
Micropower Step-Up
DC/DC Converter
AME5138
n Function Block Diagram
L
D
VIN
CIN
VIN
COUT
SW
VOUT
Vref=1.23
R1
FB
+
Enable
Comp
-
+
CL
Comp
-
R2
400ns one
Shot
Current sensing
CL Adjust
Driver
Under Voltage
Lockout
Logic
control
EN
Figure 3: AME5138 Block Diagram
2
VOUT
GND
AME, Inc.
Micropower Step-Up
DC/DC Converter
AME5138
n Pin Configuration
SOT-25
Top View
5
4
AME5138
1. SW
2. GND
AME5138
3. FB
4. EN
5. VIN
1
2
3
* Die Attach:
Conductive Epoxy
n Pin Description
Pin Number
Pin Name
Pin Description
1
SW
Power Switch input.
This is the drain of the internal NMOS power switch. Minimize the metal
trace area connected to this pin to minimize EMI.
2
GND
Ground.
Tie directly to ground plane.
Output voltage feedback input.
Set the output voltage by selecting values for R1 and R2 using:
3
FB
 V

R1 = R 2 out − 1 
 1 . 23V

Connect the ground of the feedback network to an AGND(Analog Ground)
plane which should be tied directly to the GND pin.
4
5
EN
Shutdown control input, active low.
The shutdown pin is an active low control. Tie this pin above 1V to enable
the device. Tie this pin below 0.4V to turn off the device.
VIN
Analog and Power input.
Input Supply Pin. Bypassed this pin with a capacitor as close to the device
as possible.
3
AME, Inc.
Micropower Step-Up
DC/DC Converter
AME5138
n Ordering Information
AME5138 x x x x xxx x
Special Feature
Output Voltage
Number of Pins
Package Type
Operating Ambient Temperature Range
Pin Configuration
Pin
Configuration
A
(SOT-25)
1. SW
2. GND
3. FB
4. EN
5. VIN
Operating Ambient
Package Type
Temperature Range
Number
of
Pins
Output Voltage
E: -40OC to +85OC
V: 5
ADJ: Adjustable
E: SOT-2X
Special Feature
Y: Lead free
& Low profile
Z: Lead free
n Ordering Information
Part Number
Marking*
Output Voltage
Package
Operating Ambient
Temperature Range
AME5138AEEVADJY
BDYww
ADJ
TSOT-25
-40OC to +85OC
AME5138AEEVADJZ
BDYww
ADJ
SOT-25
-40OC to +85OC
Note: ww represents the date code and pls refer to Date Code Rule before Package Dimension.
* A line on top of the first letter represents lead free plating such as BDYww.
Please consult AME sales office or authorized Rep./Distributor for the availability of package type.
4
AME, Inc.
Micropower Step-Up
DC/DC Converter
AME5138
n Absolute Maximum Ratings
Parameter
Symbol
Maximum
Unit
VIN
6
V
VEN ,VFB
VIN
V
SW Voltage
VSW
VOUT+0.3
V
N-Channel Switch Sink Current
ISW
800
mA
Input Supply Voltage
EN, VFB Voltages
ESD Classification
B*
Caution: Stress above the listed absolute maximum rating may cause permanent damage to the device
* HBM B:2000V~3999V
n Recommended Operating Conditions
Parameter
Symbol
Rating
Unit
Input Supply Voltage
VIN
2 to 5.5
V
Ambient Temperature Range
TA
-40 to +85
TJ
-40 to +125
o
C
Junction Temperature Range
n Thermal Information
Parameter
Package
Die Attach
Thermal Resistance*
(Junction to Case)
Symbol
Maximum
θJC
81
Unit
o
C/W
Thermal Resistance
(Junction to Ambient)
SOT-25
Conductive Epoxy
Internal Power Dissipation
θJA
260
PD
400
mW
Maximum Junction Temperature
150
o
Solder Iron (10 Sec)**
350
o
C
C
* Measure θJC on backside center of molding compund if IC has no tab.
** MIL-STD-202G210F
5
AME, Inc.
Micropower Step-Up
DC/DC Converter
AME5138
n Electrical Specifications
VIN=2.2V, EN = VIN, TA= 25oC Unless otherwise noted.
Parameter
Input Voltage Range
Symbol
VIN
Test Condition
Min
o
2
o
TA=-40 C to +85 C
FB = 1.3V
(Not Switching)
Quiescent Crrrent
IQ
EN = 0V
Feedback Trip Point
VFB
TA=-40oC to +85oC
Switch Current Limit
Switch RDSON
IFB
ICL
RDSON
Switch Off Time
tOFF
Switch Leakage Current
ISW
Input Undervoltage Lockout
EN Input Threshold (Low)
(Shutdown)
EN Input Threshold (High)
(Enable the device)
EN input Current
UVP
Units
5.5
V
80
90
1.199
0.01
2
1.23
1.261
8
FB = 1.23V
TA= -40 to 85oC
IOUT=10mA
TA=25oC
325
VOUT=20V
TA= -40 to 85oC
300
V
mV
0.2
0.7
350
375
µA
mA
TA= -40 to 85oC
400
0.7
1.6
400
VSW = 20V
0.05
ON/OFF Threshold
1.6
EN
Threshold
µA
150
TA= 25oC
Ω
ns
5.0
µΑ
V
0.4
V
o
TA= -40 to 85 C
1
EN = VIN , TA = 25oC
0
EN = VIN , TA = 85oC
15
EN = GND
6
69
TA= -40 to 85oC
IEN
Max
150
TA= -40 to 85oC
TA= -40 to 85oC
ISC
FB Pin Bias Current
VIN =5.5V
VIN =5.5V
Shutdown Current
VFB
Hysteresis
64
TA=25oC
FB = 1.15V
(Switching)
Feedback Hysteresis
TA=25oC
Typ
0
nA
AME, Inc.
AME5138
n Detailed Description
The AME5138 features a constant off-time control
scheme. Operation can be best understood by referring
to Figure 3. When the voltage at the FB pin is less than
1.23V, the Enable Comp in Figure 3 enables the device
and the NMOS switch is turmed on pulling the SW pin to
ground. When the NMOS switch is on, current is supplied by the output capacitor COUT. Once the current in
the inductor reaches the peak current limit, the 400ns
One Shot turns off the NMOS switch. The SW voltage
will then rise to the output voltage plus a diode drop and
the inductor current will begin to decrease as shown in
Figure 3. During this time the energy stored in the inductor is transferred to COUT and the load. After the 400ns
off-time the NMOS switch is turned on and energy is
stored in the inductor again. This energy transfer from
the inductor to the output causes a stepping effect in
the output ripple.
This cycle is continued until the voltage at FB reaches
1.23V. When FB reaches this voltage, the enable comparator then disables the device turning off the NMOS
switch and reducing the Iq of the device to 64µA. The
load current is then supplied solely by COUT indicated by
the gradually decreasing slope at the output. When the
FB pin drops slightly below 1.23V, the enable comparator enables the device and begins the cycle described
previously. The EN pin can be used to turn off the
AME5138 and reduce the Iq to 0.01µA. In shutdown mode
the output voltage will be a diode drop lower than the
input voltage.
Micropower Step-Up
DC/DC Converter
n Application Information
INDUCTOR SELECTION
The appropriate inductor for a given application is
calculated using the following equation:
 V − VIN(min) + VD 
TOFF
L =  OUT
ICL


Where V D is the schottky diode voltage, ICL is the switch
current limit found in the Typical Performance Characteristics section, and TOFF is the switch off time. When using this equation be sure to use in minimum input voltage for the application, such as for battery powered applications.
Choosing inductors with low ESR decrease power
lossed and increase efficiency.
Care should be taken when choosing an inductor. For
applications that require an input voltage that approaches
the output voltage, such as when converting a Li-ion battery voltage to 5V, the 400ns off time may not be enough
time to discharge the energy in the inductor and transfer
the energy to the output capacitor and load. This can
cause a ramping effect in the inductor current waveform
and an increased ripple on the output voltage. Using a
smaller inductor will cause the IPK to increase and will
increase the output voltage ripple further. This can be
solved by adding a 4.7pF capacitor across the R1 feedback resistor (Figure 3) and slightly increasing the output capacitor. A smaller inductor can then be used to
ensure proper discharge in the 400ns off time.
DIODE SELECTION
To maintain high efficiency, the average current rating
of the schottky diode should be larger than the peak inductor current, IPK. Schottky diodes with a low forward
drop and fast switching speeds are ideal for increasing
efficiency in portable applications. Choose a reverse breakdown of the schottky diode larger than the output voltage.
7
AME, Inc.
AME5138
CAPACITOR SELECTION
Choose low ESR capacitors for the output to minimize
output voltage ripple. Multilayer ceramic capacitors are the
best choice. For most applications, a 1µF ceramic capacitor is sufficient. For some applications a reduction in output
voltage ripple can be achieved by increasing the output capacitor. Local bypassing for the input is needed on the
AME5138. Multilayer ceramic capacitors are a good choice
for this as well. A 4.7µF capacitor is sufficient for most applications. For additional bypassing, a 100nF ceramic capacitor can be used to shunt high frequency ripple on the input.
LAYOUT CONSIDERATIONS
The input bypass capacitor CIN, as shown in Figure 3,
must be placed close to the IC. This will reduce copper
trace resistance which effects input voltage ripple of the IC.
For additional input voltage filtering, a 100nF bypass capacitor can be placed in parallel with CIN to shunt any high
frequency noise to ground. The output capacitor, COUT, should
also be placed close to the IC. Any copper trace connections for the COUT capacitor can increase the series resistance, which directly effects output voltage ripple. The feedback network, resistors R1 and R2, should be kept close to
the FB pin to minimize copper trace connections that can
inject noise into the system. The ground connection for the
feedback resistor network should connect directly to an
analog ground plane. The analog ground plane should tie
directly to the GND pin. If no analog ground plane is available, the ground connection for the feedback network should
tie directly to the GND pin. Trace connections made to the
inductor and schottky diode should be minimized to reduce
power dissipation and increase overall efficiency.
8
Micropower Step-Up
DC/DC Converter
AME, Inc.
Micropower Step-Up
DC/DC Converter
AME5138
n Application Information
L
2.2µH
VIN
2.5V-4.2V
5
1
VIN
C IN
4.7µF
Ceramic
4
5V
60mA
D
R1
100K
SW
AME5138 FB
CF B
5pF
3
EN
C OUT
1µF
Ceramic
R2
32.4K
GND
2
Figure5: Li-Ion 5V Application
L
10µH
VIN
2.5V-4.5V
5
1
VIN
C IN
4.7µF
Ceramic
4
12V
20mA
D
R1
100K
SW
AME5138 FB
3
EN
C OUT
1µF
Ceramic
R2
11.3K
GND
2
Figure6: Li-Ion 12V Application
L
10µH
VIN
5V
5
1
VIN
C IN
4.7µF
Ceramic
4
R1
100K
SW
AME5138 FB
EN
GND
2
12V
40mA
D
3
C OUT
1µF
Ceramic
R2
11.3K
Figure7: 5V to 12V Application
9
AME, Inc.
Micropower Step-Up
DC/DC Converter
AME5138
Switch Current Limit vs. VIN
Efficiency vs. Load Current
90
85
VIN =4.2V
80
400
o
TA =-40 C
350
o
TA =25 C
V IN =3.3V
75
Efficiency (%)
Switch Current Limit (mA)
450
VIN =2.5V
70
65
60
55
50
300
o
45
TA=85 C
VOUT =20V
40
250
2
2.5
3
3.5
4
4.5
5
35
0.5
5.5
2
6
10
90
VIN =5V
VIN =3.3V
V IN =4.2V
V IN =2.5V
75
VIN =4.2V
85
Eff iciency (%)
Efficiency (%)
80
70
65
60
55
VI N=3.3V
80
VIN =2.5V
75
70
65
60
55
50
50
V OUT =12V
45
40
0.5
VOUT=5V
45
40
2
6
10
14 18 22 24 25 26 30
0.5
31 37 38 46
6
18
34
Enable Current vs. VIN (Part Switching)
130
120
120
Disab le Current (µA)
140
130
110
100
o
TA=25 C
TA=85 C
80
70
60
110
130
150
190
110
100
o
TA =25 C
o
90
TA =85 C
80
70
60
o
o
TA=-40 C
50
85
Disable Current vs. VIN (Part Not Switching)
140
o
65
IOUT (mA)
IOUT (mA)
Enable Current ( µA)
17
95
85
TA =-40 C
50
40
40
2
2.5
3
3.5
4
VI N (V)
10
14
Efficiency vs. Load Current
Efficiency vs. Load Current
90
90
13
IOUT (mA)
VIN (V)
4.5
5
5.5
6
2
2.5
3
3.5
4
VIN (V)
4.5
5
5.5
6
AME, Inc.
Micropower Step-Up
DC/DC Converter
AME5138
EN Threshold vs. VIN
Switch Rdson vs. VIN
1.05
1.2
1.0
1.1
1
0.9
0.9
o
TA=25 C
0.85
Rd so n (Ω )
EN Threshold (V)
0.95
o
TA =-40 C
0.8
0.75
0.7
o
TA=85 C
0.8
o
TA=85 C
0.7
0.6
o
TA=25 C
o
0.5
0.65
TA =-40 C
0.4
0.6
0.3
0.55
0.5
0.2
2
2.5
3
3.5
4
4.5
5
5.5
6
2
2.5
3
VIN (V)
3.5
4
4.5
5
5.5
6
VIN (V)
Efficiency vs. VIN
Output Voltage vs Load Current
12.2
90
Outp ut Vo ltage (V)
12.15
Efficien cy (%)
85
o
T A=25 C
80
75
4 LEDs
IOUT=15mA
2.5
3
3.5
4
4.5
VIN =4.2V
12
11.95
V IN =5V
11.9
C OUT =4.7µF
VOUT =12V
11.8
0.5 2
5
VI N (V)
VIN =3.3V
12.05
11.85
70
2
VIN =2.5V
12.1
6
10 14 18 22 24 26 30 32 33 38 40 42 52
IOUT (mA)
FB Trip Point and FB Pin Current vs
Temperature
0.36
0.35
1.24
V FB
1.23
0.34
0.33
0.32
1.22
0.31
1.21
IFB
0.3
1.2
-40
-20
0
25
o
55
Feeback Biascurent (µA)
Feeback Trip Point (V)
1.25
0.29
85
Ambient Temperature ( C)
11
AME, Inc.
Micropower Step-Up
DC/DC Converter
AME5138
Typical Switching Waveform
Typical Switching Waveform
1
1
3
2
2
3
VOUT=20V, VIN=2.5V
VOUT = 14V, VIN=3.6V; 4LEDs
1)V SW, 20V/div,DC
IOUT = 15mA
2)V OUT, 200mV/div.AC
1) VSW, 20V / div, DC
3)Inductor Current, 200mA/div,DC
Load Current=10mA
2) Inductor Current, 100mA / div, DC
3) VOUT, 100mV / div. AC
T=10ms/div
Step Response
1
Start-Up/Shutdown
1
2
2
3
3
VOUT=20V, VIN=2.5V
VOUT = 20V, VIN = 2.5V
1)Load, 1mA to 10mA to 1mA,DC
1) EN, 1V/div,DC
2)V OUT, 200mV/div.AC
2) VOUT, 20V/div,DC
3)Inductor Current 200mA/div,DC
3) Inductor Current 200mA/div,DC
T=1ms/div
RL =1.8kΩ,
T= 200µs/div
12
AME, Inc.
Micropower Step-Up
DC/DC Converter
AME5138
n Date Code Rule
Marking
Date Code
Year
A
A
A
W
W
xxx0
A
A
A
W
W
xxx1
A
A
A
W
W
xxx2
A
A
A
W
W
xxx3
A
A
A
W
W
xxx4
A
A
A
W
W
xxx5
A
A
A
W
W
xxx6
A
A
A
W
W
xxx7
A
A
A
W
W
xxx8
A
A
A
W
W
xxx9
n Tape and Reel Dimension
SOT-25
P
W
AME
AME
PIN 1
Carrier Tape, Number of Components Per Reel and Reel Size
Package
Carrier Width (W)
Pitch (P)
Part Per Full Reel
Reel Size
SOT-25
8.0±0.1 mm
4.0±0.1 mm
3000pcs
180±1 mm
13
AME, Inc.
Micropower Step-Up
DC/DC Converter
AME5138
n Tape and Reel Dimension
TSOT-25
P
W
AME
AME
PIN 1
Carrier Tape, Number of Components Per Reel and Reel Size
14
Package
Carrier Width (W)
Pitch (P)
Part Per Full Reel
Reel Size
TSOT-25
8.0±0.1 mm
4.0±0.1 mm
3000pcs
180±1 mm
AME, Inc.
Micropower Step-Up
DC/DC Converter
AME5138
n Package Dimension
SOT-25
Top View
Side View
SYMBOLS
D
MILLIMETERS
MAX
MIN
MAX
L
MIN
INCHES
1.20REF
E
H
A
θ1
S1
A1
0.00
0.15
0.0000
0.0059
b
0.30
0.55
0.0118
0.0217
D
2.70
3.10
0.1063
0.1220
E
1.40
1.80
0.0551
0.0709
1.90 BSC
e
H
e
2.60
θ1
0
o
3.00
10
0.10236 0.11811
0.0146BSC
o
0o
10o
0.95BSC
0.0374BSC
MILLIMETERS
INCHES
S1
A1
A
0.07480 BSC
0.37BSC
L
Front View
0.0472REF
b
TSOT-25
Top View
Side View
SYMBOLS
MIN
MAX
MIN
MAX
A+A1
0.90
1.25
0.0354
0.0492
b
0.30
0.50
0.0118
0.0197
c
0.09
0.25
0.0035
0.0098
D
2.70
3.10
0.1063
0.1220
E
1.40
1.80
0.0551
0.0709
E
θ1
S1
e
1.90 BSC
e
H
2.40
A
θ1
b
S1
3.00
0.35BSC
L
Front View
0.07480 BSC
0
o
10
0.95BSC
0.09449 0.11811
0.0138BSC
o
0o
10o
0.0374BSC
A1
H
L
D
15
www.ame.com.tw
E-Mail: sales@ame.com.tw
Life Support Policy:
These products of AME, Inc. are not authorized for use as critical components in life-support
devices or systems, without the express written approval of the president
of AME, Inc.
AME, Inc. reserves the right to make changes in the circuitry and specifications of its devices and
advises its customers to obtain the latest version of relevant information.
 AME, Inc. , February 2006
Document: 1015-DS5138-A.01
Corporate Headquarter
U.S.A. (Subsidiary)
AME, Inc.
Analog Microelectronics, Inc.
2F, 302 Rui-Guang Road, Nei-Hu District
Taipei 114, Taiwan.
Tel: 886 2 2627-8687
Fax: 886 2 2659-2989
3100 De La Cruz Blvd., Suite 201
Santa Clara, CA. 95054-2046
Tel : (408) 988-2388
Fax: (408) 988-2489