ELM ELM600LA High efficiency synchronous pwm step down dc/dc converter Datasheet

ELM600LA 800mA 1.4MHz
high efficiency synchronous PWM step down DC/DC converter
■General description
ELM600LA is high efficiency synchronous step down DC/DC converter operated with current mode and 1.4MHz
constant frequency; internal switch and synchronous rectifier are integrated for high efficiency. In application,
ELM600LA does not require any external Schottky diode. Internal current consumption under operation of
ELM600LA is as low as 200µA and drops to less than 1µA in shutdown mode. With supply voltage from 2.5V
to 6V, ELM600LA can supply load current of 800mA; the output voltage can be regulated as low as 0.6V.
With 1.4MHz switching frequency, ELM600LA makes it possible to adopt small surface amount inductors and
capacitors. Switch duty cycle would be on continuously and 100% at maximum when input voltage is set be to
lower than output voltage.
■Features
■Application
•
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•
•
•
•
•
•
•
•
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•
•
Current mode operation
Thermal shutdown protection and short circuit protection
Constant frequency
: Typ.1.4MHz
: 800mA
Output current
: Max.95%
High efficiency
: Max.1µA(Ven=0V, Vin=6V)
Shutdown current
Supply voltage
: 2.5V to 6V
Low quiescent current
: Typ.200µA
: 0 to 100% (in dropout)
Full duty ratio
Package
: TSOT-25
Cellular phone
PDA and smart phone
MP3 player
Digital camera
Wireless and DSL card
Microcomputer and DSP power supply
Portable machine
■Maximum absolute ratings
Parameter
VIN power supply voltage
Apply voltage to SW
Apply voltage to EN
Apply voltage to FB
SW peak current
Power dissipation
Operating temperature range
Storage temperature range
Symbol
Vin
Vsw
Ven
Vfb
Isw
Pd
Top
Tstg
Limit
-0.3 to +6.5
GND-0.3 to Vin+0.3
GND-0.3 to Vin+0.3
GND-0.3 to Vin+0.3
1.7
200
-40 to +85
-65 to +150
Caution:Permanent damage to the device may occur when ratings above maximum absolute ones are used.
Unit
V
V
V
V
A
mW
°C
°C
■Selection guide
ELM600LA-S, ELM600LA-xx-S
Symbol
a
b
Package
Product version
c, d
Output voltage
e
Taping direction
* Taping direction is one way.
• Adj. version
L: TSOT-25
A
e.g. :
12: Vout=1.2V, 18: Vout=1.8V
S: Refer to PKG file
10 - 1
ELM600LA - S
↑↑ ↑
ab e
• Fixed version
ELM600 LA - x x - S
↑↑ ↑ ↑ ↑
ab c d e
Rev.1.1
ELM600LA 800mA 1.4MHz
high efficiency synchronous PWM step down DC/DC converter
■Pin configuration
TSOT-25(TOP VIEW)
Pin No.
1
2
3
4
5
4
5
3
2
1
Pin name
EN
GND
SW
VIN
FB
Pin description
Enable control input
Ground
Power switch output
Main supply
Voltage feedback
■Block diagram
Vin
Shut down
control
●
+
_
Current
sense
amplifier
●
Reference
M1
0.6V
FB
+
_
●
PWM
PWM
Logic
Comparator
Error
amplifier
Oscillator
● ●
SW
●
GND
M2
Clock
Zero-current
comparator
+
_
EN
Slope Comp
■Standard circuit
• Adjustable output voltage
Vout
L=2.2µH
●
●
R1
●
Cout=22µF
Vin
4
●
R2
Cin=10µF
5
VIN
SW
GND
FB
EN
ELM600LA
3
2
1
Enable
Vout=0.6×(1+R1/R2)
Vout=3.3V, R1=300KΩ, R2=68KΩ
Vout=1.8V, R1=1MΩ, R2=499KΩ
10 - 2
Rev.1.1
ELM600LA 800mA 1.4MHz
high efficiency synchronous PWM step down DC/DC converter
• Fixed output voltage
Vout=1.2V/1.8V
L=2.2µH
●
Cout=22µF
Vin
4
●
Cin=10µF
5
VIN
SW
GND
FB
EN
ELM60012LA
ELM60018LA
3
2
1
Enable
* Passive components without specified values in the above figure are optional.
■Electrical characteristics(Adjustable output voltage)
Vin=3.6V, Typical values are at Top=25°C, unless otherwise noted.
Parameter
Symbol
Test condition
Min.
Typ.
Max. Unit
Supply voltage
Vin
2.5
6.0
V
Output voltage
Adjustable
0.6
6.0
V
Vout
Feedback current
Ifb
-30.0
30.0
nA
Regulated feedback voltage
Vfb
-40°C ≤ Top ≤ +85°C
0.582 0.600 0.618
V
Reference voltage line regulation ∆Vfb/∆Vin Vin=2.5V to 6V
0.04
0.40 %/V
Output voltage line regulation
∆Vout/∆Vin Vin=2.5V to 6V
0.04
0.40 %/V
Output voltage load regulation
Vlr
0.5
%
Shutdown current
Is
Ven=0V, Vin=6V
0.01
1.00
µA
Ven=Vin, Vfb=0.65V
Quiescent current
Iq
200
µA
No switching
Ven=0V, Vfb=0.65V
Ileak
SW leakage current
-1
1
µA
Vsw=0V or 6V
RdsonP Isw=100mA
0.35
Ω
PMOSFET on resistance
NMOSFET on resistance
RdsonN Isw=-100mA
0.24
Ω
Duty cycle=100%
PMOSFET current limit
IPcl
0.8
1.1
1.5
A
Current pulse width<1ms
Oscillator frequency
Fosc
1.12
1.40
1.68 MHz
Tsd
145
°C
Thermal shutdown threshold
EN high level input voltage
Venh
-40°C ≤ Top ≤ +85°C
1.1
V
Venl
-40°C ≤ Top ≤ +85°C
0.3
V
EN low level input voltage
EN input current
Ien
Ven=0V to Vin
-1
1
µA
10 - 3
Rev.1.1
ELM600LA 800mA 1.4MHz
high efficiency synchronous PWM step down DC/DC converter
■Test circuits(Adjustable output voltage)
L=2.2µH
VIN
ELM600LA
Vin
Cout=
22µF
GND
FB
Vout
SW
EN
R1
RL
Cin=10µF
R2
■Electrical characteristics(Fixed output voltage)
Vin=3.6V, Typical values are at Top=25°C, unless otherwise noted.
Parameter
Symbol
Test condition
Min.
Typ.
Max. Unit
Supply voltage
Vin
2.5
6.0
V
Feedback current
Ifb
-30.0
30.0
nA
Regulated feedback voltage
Vfb -40°C ≤ Top ≤ +85°C
0.582 0.600 0.618
V
Reference voltage line regulation ∆Vfb/∆Vin Vin=2.5V to 6V
0.04
0.40 %/V
0.04
0.40 %/V
Output voltage line regulation ∆Vout/∆Vin Vin=2.5V to 6V
Output voltage load regulation
Vlr
0.5
%
Output range (Fixed voltage)
Vout Vin=2.5V to 6V
1.164 1.200 1.236
V
Shutdown current
Is
Ven=0V, Vin=6V
0.01
1.00
µA
Ven=Vin,Vfb=0.65V, No switching
200
µA
Quiescent current
Iq
Ven=0V, Vfb=0.65V
SW leakage current
Ileak
-1
1
µA
Vsw=0V or 6V
PMOSFET on resistance
RdsonP Isw=100mA
0.35
Ω
NMOSFET on resistance
RdsonN Isw=-100mA
0.24
Ω
Duty cycle=100%
PMOSFET current limit
IPcl
0.8
1.1
1.5
A
Current pulse width < 1ms
Oscillator frequency
Fosc
1.12
1.40
1.68 MHz
Thermal shutdown threshold
Tsd
145
°C
EN high level input voltage
Venh -40°C ≤ Top ≤ +85°C
1.1
V
EN low level input voltage
Venl -40°C ≤ Top ≤ +85°C
0.3
V
EN input current
Ien
Ven=0V to Vin
-1
1
µA
Vout=1.2V
10 - 4
Rev.1.1
ELM600LA 800mA 1.4MHz
high efficiency synchronous PWM step down DC/DC converter
Vin=3.6V, Typical values are at Top=25°C, unless otherwise noted.
Parameter
Symbol
Test condition
Min.
Typ.
Max. Unit
Supply voltage
Vin
2.5
6.0
V
Feedback current
Ifb
-30.0
30.0
nA
Regulated feedback voltage
Vfb -40°C ≤ Top ≤ +85°C
0.582 0.600 0.618
V
Reference voltage line regulation ∆Vfb/∆Vin Vin=2.5V to 6V
0.04
0.40 %/V
0.04
0.40 %/V
Output voltage line regulation ∆Vout/∆Vin Vin=2.5V to 6V
Output voltage load regulation
Vlr
0.5
%
Output range (Fixed voltage)
Vout Vin=2.5V to 6V
1.764 1.800 1.836
V
Shutdown current
Is
Ven=0V, Vin=6V
0.01
1.00
µA
Ven=Vin,Vfb=0.65V, No switching
200
µA
Quiescent current
Iq
Ven=0V, Vfb=0.65V
SW leakage current
Ileak
-1
1
µA
Vsw=0V or 6V
PMOSFET on resistance
RdsonP Isw=100mA
0.35
Ω
NMOSFET on resistance
RdsonN Isw=-100mA
0.24
Ω
Duty cycle=100%
PMOSFET current limit
IPcl
0.8
1.1
1.5
A
Current pulse width<1ms
Oscillator frequency
Fosc
1.12
1.40
1.68 MHz
Thermal shutdown threshold
Tsd
145
°C
EN high level input voltage
Venh -40°C ≤ Top ≤ +85°C
1.1
V
EN low level input voltage
Venl -40°C ≤ Top ≤ +85°C
0.3
V
EN input current
Ien
Ven=0V to Vin
-1
1
µA
Vout=1.8V
■Marking
TSOT-25
abcde
a to e : Assembly lot No.
A to Z (I, O, X excepted) and 0 to 9
10 - 5
Rev.1.1
ELM600LA 800mA 1.4MHz
high efficiency synchronous PWM step down DC/DC converter
■Application notes
ELM600LA is constant frequency current mode PWM step down converter which is suitable for applications
that require high efficiency and small assembly area and use low voltage, such as Li-ion battery. By external
resistor divider, output voltage of ELM600LA can be set within the range from 0.6V to 6V. To provide operation with high efficiency, ELM600LA consists of main switch and synchronous rectifier while external Schottky
diode is not necessary. Duty cycle of ELM600LA can reach upto 100%. Duty cycle D of step down converter is
defined as follows:
D = Ton × Fosc × 100% ≈ (Vout/Vin) × 100%
Ton=main switch on time; Fosc=oscillator frequency (1.4MHz); Vout=output voltage;Vin=input voltage
1) Current mode PWM control
Slope compensated current mode control PWM provides superior load and line response, and protection of internal main switch and synchronous rectifier to current limit by stable switching and switch cycle. ELM600LA
switches at a constant frequency (1.4MHz) and regulates output voltage. During each cycle, the PWM comparator modulates the power transferred to load by changing inductor peak current which is based on the feedback
error voltage. Under normal operation, the main switch is turned on for a certain time to ramp the inductor
current at each rising edge of the internal oscillator, and off when inductor peak current is above error voltage.
When the main switch is turned off, the synchronous rectifier will be turned on immediately and stay on until
either the next cycle begins or the inductor current drops to zero. With light load, ELM600LA would skip pulses
to improve efficiency.
2) Dropout operation
ELM600LA allows the main switch to remain on for more than one switching cycle and increases the duty
cycle while the input voltage is dropping under the output voltage. When duty cycle reaches 100%, the main
switch transistor would be on continuously to supply current to output until current limit generates. Output voltage then is input voltage minus voltage drop across main switch and inductor.
3) Short circuit protection
ELM600LA consists of short circuit protection; when output is short to ground, the oscillator frequency is reduced to prevent the inductor current from increasing beyond the P MOSFET current limit. The frequency will
return to normal values once the short circuit condition is recovered and the feedback voltage goes back to 0.6V.
4) Maximum load current
ELM600LA can operate when input voltage is down to 2.5V; however, the maximum load current would descend because of the increase IR drop which results from the ON resistor of main switch and synchronous rectifier along with the drop of input voltage. The slope compensation signal would reduce the peak inductor current
to avoid sub-harmonic oscillations when duty cycles is larger than 50%; on the contrary, it would increase the
peak inductor current when duty cycle is decreased, as which is shown in the graph.
10 - 6
Rev.1.1
ELM600LA 800mA 1.4MHz
high efficiency synchronous PWM step down DC/DC converter
■Typical characteristics
• ELM600LA(Adj.version) : Unless otherwise noted
Vout=1.8V, Cin=10µF, Cout=22µF, L=2.2µH, R1=22kΩ, R2=11kΩ, Top=25°C
• V=1.8V(AdJ.)
Vout-Vin
2.4
EFFICIENCY (%)
Iout=1mA
1.2
100mA
0.8
0.4
0
1
2
3
Vin (V)
5
60
40
20
0
0.1
6
1
10
100
1000
Iout (mA)
Start Response
Vout-Iout
Vout (V)
1.9
Vout (V)
4
Vin=5V
80
Ven=Vin=5V, No load
2
1
0
5
4
Vin=5V
1.8
3
2
Ven (V)
Vout (V)
2.0
1.6
EFFICIENCY-Iout
100
1
0
1
10
100
0
1000
Iout (mA)
Vin=5V, Iout=10mA�600mA
Time (ms)
1.5
2
Vin=5V, Iout=100mA�600mA
Vout (V)
2.5
2
1.5
2
2
1.5
1
0
0
0.5
1
1.5
2
2.5
Time (ms)
3
3.5
1
Iout (A)
Vout (V)
2
1
Load Transient Response
Load Transient Response
2.5
0.5
0
0
4
10 - 7
0.5
1
1.5
2
2.5
Time (ms)
3
3.5
Iout (A)
1.7
4
Rev.1.1
ELM600LA 800mA 1.4MHz
high efficiency synchronous PWM step down DC/DC converter
• ELM600LA(Adj.version) : Unless otherwise noted
Vout=3.3V, Cin=10µF, Cout=22µF, L=2.2µH, R1=47kΩ, R2=10.4kΩ, Top=25°C
• V=3.3V(AdJ.)
Vout-Vin
4.0
3.5
Iout=1mA
EFFICIENCY (%)
Vout (V)
3.0
2.5
2.0
100mA
1.5
EFFICIENCY-Iout
100
1.0
Vin=5V
80
60
40
20
0.5
0
1
2
3
4
Vin (V)
5
0
0.1
6
100
1000
Start Response
Vout (V)
3.4
Ven=Vin=5V, No load
3.5
3
2
1
0
5
3.3
4
3
Vin=5V
3.2
2
Ven (V)
Vout (V)
10
Iout (mA)
Vout-Iout
3.5
1
1
0
1
10
100
Iout (mA)
0
1000
1.5
2
Load Transient Response
Vin=5V, Iout=10mA�600mA
Vout (V)
3.5
Vin=5V, Iout=100mA�600mA
4
2
3
3.5
2
3
1
0
0
0.5
1
Time (ms)
1.5
1
Iout (A)
Vout (V)
1
Time (ms)
Load Transient Response
4
0.5
0
0
2
10 - 8
0.5
1
Time (ms)
1.5
Iout (A)
3.1
2
Rev.1.1
ELM600LA 800mA 1.4MHz
high efficiency synchronous PWM step down DC/DC converter
• ELM600LA-12(Fixed version) : Unless otherwise noted
Vout=1.2V, Cin=10µF, Cout=22µF, L=2.2µH, Top=25°C
• V=1.2V(Fixed)
EFFICIENCY-Iout
Vout-Vin
100
1.4
EFFICIENCY (%)
1.2
Vout (V)
1.0
Iout=1mA
0.8
0.6
100mA
0.4
Vin=5V
80
60
40
20
0.2
0
1
2
3
4
Vin (V)
5
0
0.1
6
1
10
100
Iout (mA)
1000
Start Response
Vout-Iout
Vout (V)
1.3
1.25
Ven=Vin=5V, No load
2
1
0
4
1.2
3
Vin=5V
2
1.15
Ven (V)
Vout (V)
5
1
0
1
10
100
0
1000
Iout (mA)
Load Transient Response
Vin=5V, Iout=10mA�600mA
0
2
4
6
Time (ms)
8
10
0.8
1
Vin=5V, Iout=100mA �600mA
2
Vout (V)
2
2
1.5
1
1
0
0.6
Time (s)
Load Transient Response
1.5
1
0.4
1
Iout (A)
Vout (V)
2
0.2
0
0
12
10 - 9
2
4
6
Time (ms)
8
10
Iout (A)
1.1
12
Rev.1.1
ELM600LA 800mA 1.4MHz
high efficiency synchronous PWM step down DC/DC converter
• ELM600LA-18(Fixed version) : Unless otherwise noted
Vout=1.8V, Cin=10µF, Cout=22µF, L=2.2µH, Top=25°C
• V=1.8V(Fixed)
EFFICIENCY-Iout
Vout-Vin
100
2.4
Vin=5V
80
1.6
EFFICIENCY (%)
100mA
Iout=1mA
1.2
0.8
0.4
0
1
2
3
Vin (V)
4
5
60
40
20
0
0.1
6
1
100
1000
Start Response
Vout-Iout
Ven=Vin=5V, No load
Vout (V)
1.9
1.85
Vout (V)
10
Iout (mA)
2
1
0
5
4
1.8
3
2
Vin=5V
1.75
Ven (V)
Vout (V)
2.0
1
0
1
10
100
0
1000
Iout (mA)
Load Transient Response
0.6
0.8
Time (s)
1
Vin=5V, Iout=100mA�600mA
Vout (V)
2.5
2
1.5
2
2
1.5
1
0
0
2
4
6
Time (ms)
8
10
1
Iout (A)
Vout (V)
2
0.4
Load Transient Response
Vin=5V, Iout=10mA�600mA
2.5
0.2
0
0
12
10 - 10
2
4
6
Time (ms)
8
10
Iout (A)
1.7
12
Rev.1.1