elm604pa

ELM604PA 1.4MHz, 800mA dual PWM step-down converter
■General description
ELM604PA consists of dual high efficiency PWM step-down DC/DC converters operated with current
mode and constant frequency. For each converter the integration of a main switch and a synchronous rectifier eliminates the use of an external Schottky diode. ELM604PA is ideal for the application of portable
electronic devices with a single cell Lithium-ion (Li+) battery. Each converter can supply 800mA of load current
from a 2.5V to 6V input voltage. The output voltage can be regulated as low as 0.6V. It can also run at 100%
duty cycle for low dropout applications.
■Features
■Application
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Current mode operation
Thermal shutdown protection
Short circuit protection
Constant frequency operation
Output current
Low output voltage
High efficiency
Shutdown current
Supply voltage
Full duty ratio
Package
: Typ.1.4MHz
: 800mA(on each channel)
: 0.6V
: Max.95%
: Typ.0.1µA
: 2.5V to 6.0V
: 0 to 100% (in dropout)
: TDFN10-3x3
PDAs
MP3 players
Portable instruments
Cellular and smart phones
Digital still and video cameras
Microprocessors and DSP core supplies
■Maximum absolute ratings
Parameter
VIN1/VIN2 power supply voltage
Apply voltage to SW1/SW2
Apply voltage to FB1/FB2
Apply voltage to EN1/EN2
Operating temperature range
Storage temperature range
Symbol
Vin
Vsw
Vfb
Ven
Top
Tstg
Limit
-0.3 to +6.5
-0.3 to Vin+0.3
-0.3 to Vin1/Vin2
-0.3 to Vin1/Vin2
-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
°C
°C
■Selection guide
ELM604PA-N
Symbol
a
b
c
Package
Product version
Taping direction
* Taping direction is one way.
P: TDFN10-3x3
A
N: Refer to PKG file
7-1
ELM604PA - N
↑↑ ↑
ab c
Rev.1.2
ELM604PA 1.4MHz, 800mA dual PWM step-down converter
■Pin configuration
TDFN10-3x3(TOP VIEW)
TDFN10-3x3(BOTTOM VIEW)
1
1
10
10
10
10
1
1
2
2
9
9
9
9
2
2
3
3
8
8
8
8
3
3
4
4
7
7
7
7
4
4
5
5
6
6
6
6
5
5
Pin No.
1
2
3
4
5
6
7
8
9
10
Pin name
EN1
FB1
VIN2
GND2
SW2
EN2
FB2
VIN1
GND1
SW1
Pin description
Channel 1 enable control input
Channel 1 voltage feedback
Channel 2 supply input
Channel 2 ground pin
Channel 2 power switch output
Channel 2 enable control input
Channel 2 voltage feedback
Channel 1 supply input
Channel 1 ground pin
Channel 1 power switch output
■Standard circuit
Vin1/Vin2
2.5V to6V
Cin1=
22µF
R5
1
ON/OFF
Vout1
1.8V
Cout1
10µF
L1=
4.7µH 10
8
3
VIN1
VIN2
R6
EN2
EN1
ELM604PA
SW1
SW2
6
Vout2
1.2V
C2
2
R1
1MΩ
ON/OFF
L2=
4.7µH
5
C1
Cin2=
22µF
R2
499kΩ
FB1
FB2
GND1
GND2
9
4
7
R3
300kΩ
R4
300kΩ
Cout2
10µF
* Passive components not specified values in the above figure are optional.
7- 2
Rev.1.2
ELM604PA 1.4MHz, 800mA dual PWM step-down converter
■Block diagram
Vin1/Vin2
Shut down
control
Current
sense
amplifier
Reference
●
M1
0.6V
FB1/FB2
●
+
_
+
_
●
PWM
PWM
Logic
Comparator
Error
amplifier
Oscillator
● ●
SW1/SW2
M2
Clock
Zero-current
comparator
+
_
EN1/
EN2
Slope Comp
●
GND1/GND2
■Electrical characteristics
Parameter
Supply voltage
Feedback current
Regulated feedback voltage
Reference voltage line regulation
Output voltage line regulation
Output voltage load regulation
Shutdown current
Quiescent current
SW leakage current
PMOSFET on resistance
NMOSFET on resistance
PMOSFET current limit
Oscillator frequency
Thermal shutdown threshold
EN high level input voltage
EN low level input voltage
EN input current
Vin=3.6V, Typical values are at Top=25°C, unless otherwise noted.
Test condition
Min.
Typ.
Max. Unit
2.5
6.0
V
-30.0
0.5
30.0
nA
-40°C ≤ Top ≤ +85°C
0.582 0.600 0.618
V
Vin=2.5V to 6V
0.04
0.40 %/V
Vin=2.5V to 6V
0.04
0.40 %/V
0.5
%
Ven=0V, Vin=6V
0.01
1.00
µA
Ven=Vin, Vfb=0.65V
Iq
200
µA
No switching
Ven=0V, Vfb=0.65V
Ileak
-1
1
µA
Vsw=0V or 6V
RdsonP Isw=100mA
0.35
Ω
RdsonN Isw=-100mA
0.24
Ω
Duty cycle=100%
IPcl
0.8
1.1
1.5
A
Current pulse width<1ms
Fosc
1.12
1.40
1.68 MHz
Ts
145
°C
Venh
-40°C ≤ Top ≤ +85°C
-1.1
V
Venl
-40°C ≤ Top ≤ +85°C
0.3
V
Ien
Ven=0V to Vin
-1
1
µA
Symbol
Vin
Ifb
Vfb
∆Vfb
∆Vout
Vlr
Is
7- 3
Rev.1.2
ELM604PA 1.4MHz, 800mA dual PWM step-down converter
■Marking
TDFN10-3x3
abcde
fghijk
lmnop
Mark
a to p
Content
Assembly lot No.:
0 to 9 & A to Z
■Application notes
ELM604PA has dual independent constant frequency current mode PWM step-down converters.
ELM604PA is optimized for low voltage, Li-ion battery powered applications where high efficiency and
small size are critical. ELM604PA uses external resistor dividers to set two output voltages indepe
ndently from 0.6V to 6V. The device integrates both main switches and synchronous rectifiers, which provides high efficiency and eliminates the need for an external Schottky diode. ELM604PA can achieve 100% duty cycle. The duty cycle D of each step-down converter is defined as:
D = Ton × Fosc × 100% ≈ (Vout/Vin) × 100%
Where Ton is the main switch on time, Fosc is the oscillator frequency (1.4MHz), Vout is the output voltage
and Vin is the input voltage.
1) Current mode PWM Control
Slope compensated current mode PWM control provides stable switching and cycle-by-cycle current limit for superior load and line response and protection of the internal main switch and synchronous rec
tifier. Each channel switches at a constant frequency (1.4MHz) and regulates the output voltage. During each cycle the PWM comparator modulates the power transferred to the load by changing the induct
or peak current based on the feedback error voltage. During normal operation, the main switch is tur
ned on for a certain time to ramp the inductor current at each rising edge of the internal oscillato
r, and switched off when the peak inductor current is above the error voltage. When the main switch is off, the synchronous rectifier will be turned on immediately and stay on until the next cycle starts.
2) Dropout operation
Each channel of the ELM604PA allows the main switch to remain on for more than one switching cycle a
nd increases the duty cycle while the input voltage is dropping close to the output voltage. When the duty cycle reaches 100%, the main switch is held on continuously to deliver current to the output up to the P MOSFET current limit. The output voltage then is the input voltage minus the voltage drop across the main switch and the inductor.
7- 4
Rev.1.2
ELM604PA 1.4MHz, 800mA dual PWM step-down converter
3) Short circuit protection
ELM604PA has short circuit protection. When the output is shorted 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 the normal values once the short circuit condition is removed and the feedback voltage reaches 0.6V.
4) Maximum load current
ELM604PA can operate down to 2.5V input voltage, however the maximum load current decreases at lower
input due to large IR drop on the main switch and synchronous rectifier. The slope compensation signal reduces the peak inductor current as a function of the duty cycle to prevent sub-harmonic oscillations at duty cycles greater than 50%. Conversely the current limit increases as the duty cycle decreases.
7- 5
Rev.1.2
ELM604PA 1.4MHz, 800mA dual PWM step-down converter
■Typical characteristics
• Vout=1.8V : Unless otherwise noted
• V=1.8V
Cin1=22µF, Cout1=10µF, C1=1000pF, L1=4.7µH, R1=100kΩ, R2=50kΩ, Top=25°C
Ven=2V, Vin=5V, No load
Vout (V)
100
Vin=5V
80
60
2
1
0
40
2
1
20
0
0
0.1
1
10
100
0
1000
2
Iout (mA)
Vout-Iout
1.9
4
Time (ms)
6
Ven (V)
EFFICIENCY (%)
Start Response
EFFICIENCY-Iout
8
Vout-Vin
2.4
Vout (V)
Vout (V)
2.0
1.8
Vin=5V
Iout=1mA
1.6
100mA
1.2
0.8
0.4
1
10
100
1000
Iout (mA)
0
3
4
Vin (V)
5
Vin=5V, Iout=10mA�600mA
Vin=5V, Iout=100mA�600mA
Vout (V)
2.5
2
2
1.5
1.5
1
1
0
0
0.5
1
1.5
2
2.5
Time (ms)
3
3.5
Iout (A)
Vout (V)
2
Load Transient Response
Load Transient Response
2.5
1
0
0
4
7- 6
0.5
1
1.5
2
2.5
Time (ms)
3
3.5
Iout (A)
1.7
4
Rev.1.2
ELM604PA 1.4MHz, 800mA dual PWM step-down converter
• Vout=3.3V : Unless otherwise noted
•Cin2=22µF,
V=3.3V Cout2=10µF, C2=1000pF, L2=4.7µH, R3=150kΩ, R4=33kΩ, Top=25°C
100
Vin=5V
80
Ven=2V, Vin=5V, No load
4
Vout (V)
60
2
0
40
2
1
20
0
0
0.1
1
10
100
0
1000
2
Iout (mA)
Vout-Iout
3.35
4
Time (ms)
6
Ven (V)
EFFICIENCY (%)
Start Response
EFFICIENCY-Iout
8
Vout-Vin
3.5
3.0
3.3
3.25
Vout (V)
Vout (V)
2.5
Vin=5V
Iout=1mA
2.0
100mA
1.5
1.0
3.2
0.5
1
10
100
1000
Iout (mA)
0
Vin=5V, Iout=10mA�600mA
Vout (V)
0
1
1.5
2
2.5
Time (ms)
3
3.5
5
Vin=5V, Iout=100mA�600mA
3.5
3
2.5
1
0.5
4
1
Iout (A)
Vout (V)
3
0
3
Vin (V)
4
3.5
2.5
2
Load Transient Response
Load Transient Response
4
1
0
0
4
7- 7
0.5
1
1.5
2
2.5
Time (ms)
3
3.5
Iout (A)
3.15
4
Rev.1.2