RM590L Series
400mA Synchronous Step-down DC/DC Module with MODE pin and Inductor
No.EA-592-210906
OVERVIEW
The RM590L is a synchronous, step-down DC/DC converter which delivers up to 400mA of output current.
The RM590L can be configured for either PWM/VFM automatic shift operation or forced PWM operation by
controlling of MODE pin.
It has a built-in inductor and is available in 2.2 (mm) x 2.0 (mm) x 1.5 (mm) sized QFN2220-8 package for
high density mounting. Therefore, it is possible to save space in the mounting area.
KEY BENEFITS
● Having an inductor built-in, it is possible to simplify the board design and reduce the mounting area.
● PWM/VFM automatic shift operation provides high efficiency at light loads.
● Having an inductor built-in, the number of parts can be reduced, and the man-hours for managing
purchased parts can be reduced (concern about EOL).
•
•
•
•
•
•
•
•
Input Voltage Range (Maximum Rating):
2.3 V to 5.5 V (6.5 V)
Output Voltage (Fixed Output Voltages):
from 0.6V to 3.3V in 0.1V increments
±1.5% (VSET ≥ 1.2 V), ±18 mV (VSET < 1.2 V)
Output Voltage Accuracy
Output Voltage (Adjustable Output Voltages):
0.6 V to 5.5 V
0.6V Reference (VFB), ±9 mV Voltage Accuracy
Selectable Oscillator Frequency: Typ. 6.0 MHz
Oscillator Maximum Duty: Min. 100%
MOSFET ON Resistance (VIN = 3.6 V):
High Side MOSFET Typ. 0.245 Ω
Low Side MOSFET Typ. 0.225 Ω
UVLO Detector Threshold: Typ. 2.0 V
Soft-start Time: Typ. 0.15 ms
Thermal Shutdown Function:
Detection Temperature 140°C
Release Temperature 100°C
Efficiency
VOUT=1.8V
100
90
VFM / PWM Auto
80
70
Efficiency η [%]
•
TYPICAL CHARACTERISTICS
KEY SPECIFICATIONS
60
40
30
20
10
0
0.01
0.1
1
10
100
1000
Output Current IOUT [mA]
TYPICAL APPLICATIONS
VIN
LX
VIN
CIN
MODE Control
VOUT
L1
L2
COUT
MODE
VOUT
RM590L
CE
GND
CE Control
Fixed Output Voltage Type (RM590Lxx2A/B)
VIN
PACKAGE
Forced PWM
VIN = 3.6V
VIN ==2.7V
VIN
2.7V
VIN ==3.6V
VIN
3.6V
VIN ==4.2V
VIN
4.2V
VIN ==5.0V
VIN
5.0V
50
LX
VIN
VOUT
L1
L2
R1
CIN
MODE Control
QFN2220-8
2.2 x 2.0 x 1.5 (mm)
MODE
VFB
RM590L
CE
C1
COUT
R2
GND
CE Control
Adjustable Output Voltage Type (RM590L002C/D)
APPLICATIONS
•
•
•
•
Devices need to be miniaturized such as wearables, hearables
Phones, domestic LAN systems
Communication modules, and applications for Industrial equipment
Instrumentation equipment such as flow meters and pressure gauges
1
RM590L
No.EA-592-210906
SELECTION GUIDE
The set output voltage, the output voltage type, and the auto-discharge function are user-selectable options.
Selection Guide
Product Name
Package
Quantity per Reel
Pb Free
Halogen Free
RM590Lxx2$-TR
QFN2220-8
2,000
Yes
Yes
xx：Set Output Voltage (VSET)
Fixed Output Voltage Type：06 to 33 (0.6 V to 3.3 V, 0.1 V steps)
The voltage in 0.05 V step is shown as follows.
Ex. 1.25 V: RM590L122$5
Refer to Product-specific Electrical Characteristics for details.
Adjustable Output Voltage Type：00
$ ：Versions
＄
A
B
C
D
Output Voltage Type
Fixed
Adjustable
Auto-discharge Function
No
Yes
No
Yes
VSET
0.6 V to 3.3 V
0.6 V to 5.5 V
2
RM590L
No.EA-592-210906
BLOCK DIAGRAMS
RM590Lxx2A/B (Fixed Output Voltage Type)
L2
L1
UVLO
MODE
Mode
Control
Slope
Generator
Vref
Thermal
Protection
On Time
Control
Hi Side
Current
Detector
VIN
Switching
Control
LX
Comp.
Soft Start
Amp.
VOUT
Low Side
Current
Detector
CE
GND
Enable
Control
RM590Lxx2A Block Diagram
L2
L1
UVLO
MODE
Mode
Control
Slope
Generator
Vref
Thermal
Protection
On Time
Control
Hi Side
Current
Detector
VIN
Switching
Control
LX
Comp.
Soft Start
Amp.
VOUT
Low Side
Current
Detector
CE
GND
Enable
Control
RM590Lxx2B Block Diagram
3
RM590L
No.EA-592-210906
RM590L002C/D (Adjustable Output Voltage Type)
L2
L1
UVLO
MODE
Mode
Control
Slope
Generator
Vref
Thermal
Protection
On Time
Control
Hi Side
Current
Detector
VIN
Switching
Control
LX
Comp.
Soft Start
Amp.
VFB
Low Side
Current
Detector
CE
GND
Enable
Control
RM590L002C Block Diagram
L2
L1
UVLO
MODE
Mode
Control
Slope
Generator
Vref
Thermal
Protection
On Time
Control
Hi Side
Current
Detector
VIN
Switching
Control
LX
Comp.
Soft Start
Amp.
VFB
Low Side
Current
Detector
CE
GND
Enable
Control
RM590L002D Block Diagram
4
RM590L
No.EA-592-210906
PIN DESCRIPTIONS
Top View
7
6
Bottom View
5
5
8
4
4
3
1
2
6
7
8
2
1
3
RM590L(QFN2220-8）Pin Configuration
RM590L (QFN2220-8) Pin Descriptions
Pin No.
Symbol
I/O
Description
Output/Feedback Pin
Fixed Output Voltage Type: Connect to VOUT pin and L2 pin.
Adjustable Output Voltage Type: Receives the feedback voltage from a
1
VOUT/VFB
I
Resistive divider connected across the output. Refer to “Adjustable
Output Voltage Setting”
Switch Node Connection to the Inductor.
This pin connects to the drains of the internal Main and synchronous
2
LX
O
power MOSFET switches.
Mode Select Input.
To select forced PWM, connect this pin to a voltage above designated
"High".
3
MODE
I
Connecting this pin to a voltage between 0 V and designated "Low"
selects PWM/VFM automatic shift operation mode.
Inductor Pin 1 (Input pin of inductor built-in.)
4
L1
I
Connect this pin to Lx pin.
Power Input Supply.
5
VIN
I
Decouple this pin to GND with a capacitor.
Forcing this pin below designated "Low" level shuts down the RM590L.
In shutdown all functions are disabled except auto discharge function.
6
CE
I
(option)
Ground Pin
7
GND
I
Inductor Pin 2 (This pin connects to built-in inductor)
8
L2
O
Connect a capacitor between this pin and GND.
5
RM590L
No.EA-592-210906
ABSOLUTE MAXIMUM RATINGS
Symbol
VIN
VLX
VCE
VMODE
VOUT/VFB
ILX
PD
Item
Input Voltage
LX / L1 / L2 Pin Voltage
CE Pin Voltage
MODE Pin Voltage
VOUT / VFB Pin Voltage
LX / L1 / L2 Pin Input / Output Current
Power Dissipation
Ratings
−0.3 to 6.5
−0.3 to VIN +0.3
−0.3 to 6.5
−0.3 to 6.5
−0.3 to 6.5
1.6
Unit
V
V
V
V
V
A
Refer to Appendix "POWER DISSIPATION"
Tj
Junction Temperature Range
−40 to 125
°C
Tstg
Storage Temperature Range
−55 to 125
°C
ABSOLUTE MAXIMUM RATINGS
Electronic and mechanical stress momentarily exceeded absolute maximum ratings may cause permanent damage
and may degrade the lifetime and safety for both device and system using the device in the field. The functional
operation at or over these absolute maximum ratings are not assured.
ELECTROSTATIC DISCHARGE (ESD) RATINGS
Symbol
VHBM
VCDM
Conditions
HBM C = 100pF, R = 1.5kΩ
CDM
Ratings
-750 / +2000
± 1000
Unit
V
V
ELECTROSTATIC DISCHARGE RATINGS
The electrostatic discharge test is done based on JESD47.
In the HBM method, ESD is applied using the power supply pin and GND pin as reference pins.
RECOMMENDED OPERATING CONDITIONS
Symbol
VIN
Ta
Item
Input Voltage
Operating Temperature Range
Ratings
2.3 to 5.5
−40 to 85
Unit
V
°C
RECOMMENDED OPERATING CONDITIONS
All of electronic equipment should be designed that the mounted semiconductor devices operate within the
recommended operating conditions. The semiconductor devices cannot operate normally over the recommended
operating conditions, even if they are used over such ratings by momentary electronic noise or surge. And the
semiconductor devices may receive serious damage when they continue to operate over the recommended operating
conditions.
6
RM590L
No.EA-592-210906
ELECTRICAL CHARACTERISTICS
The specifications surrounded by
are guaranteed by design engineering at -40°C ≤ Ta ≤ 85°C.
RM590Lxx2A/B Electrical Characteristics
Symbol
VOUT
(Ta = 25°C)
Parameter
Output Voltage
Conditions
Min.
Typ.
VIN = VCE = 3.6 V
VSET ≥ 1.2 V x 0.985
(VSET ≤ 2.6 V),
VIN = VCE = VSET + 1 V
VSET < 1.2 V −0.018
(VSET > 2.6 V)
fOSC
Oscillator Frequency
VIN = VCE = 3.6 V, VSET = 1.8 V,
"Closed Loop Control"
IDD
Supply Current
VIN = VCE = VOUT = 3.6 V, VMODE = 0 V
4.8
Max.
Unit
x 1.015
V
+0.018
6.0
7.2
MHz
µA
15
Standby Current
VIN = 5.5 V, VCE = 0 V
0
5
µA
ICEH
CE "High" Input Current
VIN = VCE = 5.5 V
−1
0
1
µA
ICEL
CE "Low" Input Current
VIN = 5.5 V, VCE = 0 V
−1
0
1
µA
IMODEH
MODE "High" Input Current
VIN = VMODE = 5.5 V, VCE = 0 V
−1
0
1
µA
IMODEL
MODE "Low" Input Current
VIN = 5.5 V, VCE = VMODE = 0 V
−1
0
1
µA
IVOUTH
VOUT "High" Input Current
VIN = VOUT = 5.5 V, VCE = 0 V
−1
0
1
µA
IVOUTL
VOUT "Low" Input Current
VIN = 5.5 V, VCE = VOUT = 0 V
−1
0
1
µA
RDISTR
Auto-discharge MOSFET
On-resistance ( １)
VIN = 3.6 V, VCE = 0 V
ILXLEAKH
LX "High" Leakage Current
VIN = VLX = 5.5 V, VCE = 0 V
−1
0
5
µA
ILXLEAKL
LX "Low" Leakage Current
VIN = 5.5 V, VCE = VLX = 0 V
−5
0
1
µA
VCEH
CE "High" Input Voltage
VIN = 5.5 V
1.0
VCEL
ISTANDBY
Ω
40
V
CE "Low" Input Voltage
VIN = 2.3 V
VMODEH
MODE "High" Input Voltage
VIN = VCE = 5.5 V
VMODEL
MODE "Low" Input Voltage
VSET ≤ 2.3 V, VIN = VCE = 2.3 V
VSET > 2.3 V, VIN = VSET
RONP
On-resistance of High Side MOSFET
VIN = 3.6 V, ILX = −100 mA
0.245
Ω
RONN
On-resistance of Low Side MOSFET
VIN = 3.6 V, ILX = −100 mA
0.225
Ω
Maxduty Maximum Duty Cycle
0.4
1.0
V
V
0.4
V
%
100
tSTART
Soft-start Time
VIN = VCE = 3.6 V (VSET ≤ 2.6 V),
VIN = VCE = VSET + 1 V (VSET > 2.6 V)
ILXLIM
LX Current Limit
VIN = VCE = 3.6 V (VSET ≤ 2.6 V),
VIN = VCE = VSET + 1 V (VSET > 2.6 V)
600
1000
VIN = VCE, Falling
1.85
2.00
2.20
V
1.90
2.05
2.25
V
VUVLO1
VUVLO2
UVLO Threshold Voltage
VIN = VCE, Rising
150
300
µs
mA
All test items listed under Electrical Characteristics are done under the pulse load condition (Tj ≈ Ta = 25°C).
Test circuit is operated with “Open Loop Control” (GND = 0 V), unless otherwise specified.
(１)
RM590Lxx2B only
7
RM590L
No.EA-592-210906
The specifications surrounded by
are guaranteed by design engineering at -40°C ≤ Ta ≤ 85°C.
RM590L002C/D Electrical Characteristics
Symbol
VFB
(Ta = 25°C)
Parameter
Conditions
Feedback Voltage
VIN = VCE = 3.6 V
fOSC
Oscillator Frequency
VIN = VCE = 3.6 V, VSET = 1.8 V,
"Closed Loop Control"
IDD
Supply Current
VIN = VCE = VOUT = 3.6 V, VMODE = 0 V
Standby Current
VIN = 5.5 V, VCE = 0 V
ICEH
CE "High" Input Current
VIN = VCE = 5.5 V
ICEL
CE "Low" Input Current
IMODEH
Min.
Typ.
Max.
Unit
0.591
0.600
0.609
V
4.8
6.0
7.2
MHz
µA
15
0
5
µA
−1
0
1
µA
VIN = 5.5 V, VCE = 0 V
−1
0
1
µA
MODE "High" Input Current
VIN = VMODE = 5.5 V, VCE = 0 V
−1
0
1
µA
IMODEL
MODE "Low" Input Current
VIN = 5.5 V, VCE = VMODE = 0 V
−1
0
1
µA
IVOUTH
VOUT "High" Input Current
VIN = VOUT = 5.5 V, VCE = 0 V
−1
0
1
µA
IVOUTL
VOUT "Low" Input Current
VIN = 5.5 V, VCE = VOUT = 0 V
−1
0
1
µA
RDISTR
Auto-discharge MOSFET
On-resistance ( １)
VIN = 3.6 V, VCE = 0 V
ILXLEAKH
LX "High" Leakage Current
VIN = VLX = 5.5 V, VCE = 0 V
−1
0
5
µA
ILXLEAKL
LX "Low" Leakage Current
VIN = 5.5 V, VCE = VLX = 0 V
−5
0
1
µA
VCEH
CE "High" Input Voltage
VIN = 5.5 V
1.0
VCEL
CE "Low" Input Voltage
VIN = 2.3 V
VMODEH
MODE "High" Input Voltage
VIN = VCE = 5.5 V
VMODEL
MODE "Low" Input Voltage
VSET ≤ 2.3 V, VIN = VCE = 2.3 V
VSET > 2.3 V, VIN = VSET
RONP
On-resistance of High Side MOSFET
VIN = 3.6 V, ILX = −100 mA
0.245
Ω
RONN
On-resistance of Low Side MOSFET
VIN = 3.6 V, ILX = −100 mA
0.225
Ω
ISTANDBY
Maxduty Maximum Duty Cycle
Soft-start Time
VIN = VCE = 3.6 V (VSET ≤ 2.6 V),
VIN = VCE = VSET + 1 V (VSET > 2.6 V)
ILXLIM
LX Current Limit
VIN = VCE = 3.6 V (VSET ≤ 2.6 V),
VIN = VCE = VSET + 1 V (VSET > 2.6 V)
VUVLO2
UVLO Threshold Voltage
V
0.4
1.0
V
V
0.4
V
%
100
tSTART
VUVLO1
Ω
40
150
300
µs
mA
600
1000
VIN = VCE, Falling
1.85
2.00
2.20
V
VIN = VCE, Rising
1.90
2.05
2.25
V
All test items listed under Electrical Characteristics are done under the pulse load condition (Tj ≈ Ta = 25°C).
Test circuit is operated with “Open Loop Control” (GND = 0 V), unless otherwise specified.
(１)
RM590L002D only
8
RM590L
No.EA-592-210906
The specifications surrounded by
are guaranteed by Design Engineering at −40°C ≤ Ta ≤ 85°C
RM590L series (Fixed Output Voltage Type) Product-specific Electrical Characteristics
(Ta = 25°C)
Product Name
RM590L062x
RM590L072x
RM590L082x
RM590L092x
RM590L102x
RM590L102x5
RM590L112x
RM590L112x5
RM590L122x
RM590L132x
RM590L142x
RM590L152x
RM590L162x
RM590L172x
RM590L182x
RM590L192x
RM590L202x
RM590L212x
RM590L222x
RM590L232x
RM590L242x
RM590L252x
RM590L262x
RM590L272x
RM590L282x
RM590L292x
RM590L302x
RM590L312x
RM590L322x
RM590L332x
Min.
0.582
0.682
0.782
0.882
0.982
1.032
1.082
1.132
1.182
1.281
1.379
1.478
1.576
1.675
1.773
1.872
1.970
2.069
2.167
2.266
2.364
2.463
2.561
2.660
2.758
2.857
2.955
3.054
3.152
3.251
VOUT [V]
VSET
0.600
0.700
0.800
0.900
1.000
1.050
1.100
1.150
1.200
1.300
1.400
1.500
1.600
1.700
1.800
1.900
2.000
2.100
2.200
2.300
2.400
2.500
2.600
2.700
2.800
2.900
3.000
3.100
3.200
3.300
Max.
0.618
0.718
0.818
0.918
1.018
1.068
1.118
1.168
1.218
1.319
1.421
1.522
1.624
1.725
1.827
1.928
2.030
2.131
2.233
2.334
2.436
2.537
2.639
2.740
2.842
2.943
3.045
3.146
3.248
3.349
9
RM590L
No.EA-592-210906
TYPICAL APPLICATION CIRCUIT
VIN
LX
VIN
CIN
MODE Control
VOUT
L1
L2
COUT
MODE
VOUT
RM590L
CE
GND
CE Control
RM590Lxx2A/B (Fixed Output Voltage Type)
VIN
LX
VIN
VOUT
L1
L2
R1
CIN
MODE Control
MODE
VFB
RM590L
CE
C1
COUT
R2
GND
CE Control
RM590L002C/D (Adjustable Output Voltage Type)
Recommended External Components
Symbol
CIN
COUT
Descriptions
4.7 µF and more, Ceramic Capacitor
10 µF, Ceramic Capacitor
10
RM590L
No.EA-592-210906
Precautions for the Selection of External Parts
Choose a low ESR ceramic capacitor. The capacitance of CIN between VIN and GND should be more than or
equal to 4.7 µF. The capacitance of a ceramic capacitor (COUT) should be 10 µF. Also, choose the capacitor
with consideration for bias characteristics and input/output voltages.
11
RM590L
No.EA-592-210906
OPERATION
Chip Enable Function
Forcing above designated "High" voltage to CE pin, the RM590L becomes active. Forcing below designated
"Low" voltage to CE pin shuts down the RM590L. In shutdown (Standby) condition, all functions are disabled
except Auto Discharge function. (Option) With Auto-Discharge option, the MOSFET to discharge the output
capacitor turns on and the output is pulled down to GND. Without Auto-Discharge option, the output
becomes "Hi-Z". CE pin can accept input range voltage regardless of the input of VIN pin. If Chip Enable
function is not necessary, tie CE pin to VIN pin or other designated "High" voltage node at start-up.
Soft-start Time
Starting-up with CE Pin
The IC starts to operate when the CE pin voltage (VCE) exceeds the threshold voltage. The threshold voltage
is preset between CE "High" input voltage (VCEH) and CE "Low" input voltage (VCEL).
After the start-of the start-up of the IC, soft-start circuit starts to operate. Then, after a certain period of time,
the reference voltage (VREF) in the IC gradually increases up to the specified value.
Notes: Soft start time (tSTART)( １) is not always equal to the turn-on speed of the step-down DC/DC module.
Please note that the turn-on speed could be affected by the power supply capacity, the output current, the
inductance value and the COUT value.
CE Pin Input Voltage
(VCE)
IC Internal Reference Voltage
(VREF)
LX Voltage
(VLX)
Output Voltage
(VOUT)
VCEH
Threshold Level
VCEL
Soft-start Time (tSTART)
Soft-start Circuit
operation starts.
Depending on Power Supply,
Load Current, External Components
Timing Chart when Starting-up with CE Pin
(１)
Soft-start time (tSTART) indicates the duration until the reference voltage (VREF) reaches the specified voltage after
soft-start circuit’s activation.
12
RM590L
No.EA-592-210906
Starting-up with Power Supply
After the power-on, when VIN exceeds the UVLO released voltage (VUVLO2), the IC starts to operate. Then, softstart circuit starts to operate and after a certain period of time, VREF gradually increases up to the specified
value.
Notes: Please note that the turn-on speed of VOUT could be affected by the power supply capacity, the output
current, the inductance value, the COUT value and the turn-on speed of VIN determined by CIN.
VUVLO2
Input Voltage
(VIN)
Soft-start Time (tSTART)
IC Internal Reference Voltage
(VREF)
LX Voltage
(VLX)
VSET
Output Voltage
(VOUT)
Depending on Power Supply, Load Current,
External Components
Timing Chart when Starting-up with Power Supply
Auto Discharge Function
When turned off, the Vout voltage drops rapidly to near 0V by discharging the charge stored in the output
capacitor through the MOSFET connected between the LX and GND pins. The auto discharge function is
enabled when the CE pin = "low" or the thermal shutdown detection or the UVLO detection. On-resistance of
MOSFET is Typ. 40Ω. This function may be required to meet the required sequence for electronic components
powered by this device.
13
RM590L
No.EA-592-210906
Undervoltage Lockout (UVLO) Circuit
If VIN becomes lower than VSET, the step-down DC/DC module stops the switching operation and ON duty
becomes 100%, and then VOUT gradually drops according to VIN.
If the VIN drops more and becomes lower than the UVLO detector threshold (VUVLO1), the UVLO circuit starts
to operate, VREF stops, and High Side and Low Side built-in MOSFETs turn "OFF". As a result, VOUT drops
according to the COUT capacitance value and the load.
To restart the operation, VIN needs to be higher than VUVLO2. The timing chart below shows the voltage shifts
of VREF, VLX and VOUT when VIN value is varied.
Notes: Falling edge (operating) and rising edge (releasing) waveforms of VOUT could be affected by the initial
voltage of COUT and the output current of VOUT.
Input Voltage
(VIN)
VSET
VUVLO2
VUVLO1
Soft-start Time (tSTART)
IC Internal Reference Voltage
(VREF)
LX Voltage
(VLX)
Output Voltage
(VOUT)
VOUT
Depending on Power Supply, Load Current,
External Components
Timing Chart with Variations in Input Voltage (VIN)
14
RM590L
No.EA-592-210906
Current limiting circuit
Current limit circuit supervises the inductor peak current (the peak current flowing through High Side MOSFET)
in each switching cycle, and if the current exceeds the LX current limit (ILXLIM), it turns off High Side MOSFET
ILXLIM of the RM590L is set to Typ.1.0 A.
Over Current Protection
LX Current Limit
(ILXLIM)
LX Current
High Side MOSFET Current
LX Voltage
(VLX)
Over-Current Protection Operation
15
RM590L
No.EA-592-210906
Operation of Step-down DC/DC module and Output Current
The step-down DC/DC module charges energy in the inductor when LX MOSFET turns “ON”, and discharges
the energy from the inductor when LX MOSFET turns “OFF” and controls with less energy loss, so that a lower
output voltage (VOUT) than the input voltage (VIN) can be obtained. The operation of the step-down DC/DC
module is explained in the following figures.
IL
ILMAX
i1
VIN
High Side MOSFET
Low Side MOSFET
VOUT
L
ILMIN
tOPEN
i1
i2
i2
CL
GND
tON
tOFF
T＝1/fOSC
Basic Circuit
Step1.
Inductor Current (IL) flowing through
Inductor (L)
High Side MOSFET turns “ON” and IL (i1) flows, L is charged with energy. At this moment, i1
increases from the minimum inductor current (ILMIN), which is 0 A, and reaches the maximum inductor
current (ILMAX) in proportion to the on-time period (tON) of High Side MOSFET.
Step2.
When High Side MOSFET turns “OFF”, L tries to maintain IL at ILMAX, so L turns Low Side MOSFET
“ON” and IL (i2) flows into L.
Step3.
i2 decreases gradually and reaches ILMIN after the open-time period (tOPEN) of Low Side MOSFET, and
then Low Side MOSFET turns “OFF”. This is called discontinuous current mode.
As the output current (IOUT) increases, the off-time period (tOFF) of High Side MOSFET runs out before
IL reaches ILMIN. The next cycle starts, and High Side MOSFET turns “ON” and Low Side MOSFET
turns “OFF”, which means IL starts increasing from ILMIN. This is called continuous current mode.
In PWM mode, VOUT is maintained by controlling tON. The oscillator frequency (fOSC) is maintained constant
during PWM mode.
When the step-down DC/DC operation is constant, ILMIN and ILMAX during tON of High Side MOSFET would be
same as during tOFF of High Side MOSFET. The current differential between ILMAX and ILMIN is described as ∆I,
as the following equation (1).
∆I = ILMAX − ILMIN = VOUT × tOPEN / 0.5 = (VIN − VOUT) × tON / 0.5 ························································ (1)
The above equation is predicated on the following requirements.
T = 1 / fOSC = tON + tOFF
duty (%) = tON / T × 100 = tON × fOSC × 100
tOPEN ≤ tOFF
In Equation 1, “VOUT × tOPEN / 0.5” shows the amount of current change in "OFF" state. Also, “(VIN − VOUT) × tON
/ L0.5” shows the amount of current change at "ON" state.
16
RM590L
No.EA-592-210906
Discontinuous Mode and Continuous Mode
As illustrated in Figure A., when IOUT is relatively small, tOPEN < tOFF. In this case, the energy charged into L
during tON will be completely discharged during tOFF, as a result, ILMIN = 0. This is called discontinuous mode.
When IOUT is gradually increased, eventually tOPEN = tOFF and when IOUT is increased further, eventually ILMIN >
0 as illustrated in Figure B. This is called continuous mode.
IL
ILMAX
IL
ILMAX
ILMIN
ILMIN
tOPEN
t
tON
ICONST
t
tOFF
tON
T=1/fOSC
Figure A. Discontinuous Mode
tOFF
T=1/fOSC
Figure B. Continuous Mode
In the continuous mode, the solution of Equation (1) is described as tONC.
tONC = T × VOUT / VIN ··············································································································· (2)
When tON < tONC, it is discontinuous mode, and when tON = tONC, it is continuous mode.
17
RM590L
No.EA-592-210906
Forced PWM Mode and VFM Mode
Output voltage controlling method is selectable between a forced PWM control type and a PWM/VFM autoswitching control type, and can be set by the MODE pin. The forced PWM control switches at fixed frequency
rate in order to reduce noise in low output current. The PWM/VFM auto-switching control automatically
switches from PWM mode to VFM mode in order to achieve high efficiency in low output current.
Forced PWM Mode
By setting the MODE pin to "High", the IC switches the frequency at the fixed rate to reduce noise even when
the output load is light. Therefore, when IOUT is ∆IL/2 or less, ILMIN becomes less than “0”. That is, the
accumulated electricity in CL is discharged through the IC side while IL is increasing from ILMIN to “0” during tON,
and also while IL is decreasing from “0” to ILMIN during tOFF.
VFM Mode
By setting the MODE pin to "Low", in low output current, the IC automatically switches into VFM mode in order
to achieve high efficiency. In VFM mode, tON is determined depending on VIN and VOUT.
ILMAX
IL
ILMAX
IL
ΔIL
IOUT
0
0
ILMIN
ILMIN
t
tON
tOFF
t
tON
tOFF
T=1/fOSC
Forced PWM Mode
VFM Mode
18
RM590L
No.EA-592-210906
Thermal Shutdown Function
When the junction temperature exceeds the thermal shutdown detection temperature (Typ. 140°C), this IC
cuts off the output and suppresses the self-heating. When the junction temperature falls below the thermal
shutdown release temperature (Typ. 100°C), this IC will restart with the soft start operation.
Thermal
Shutdown
Release
Detect
Release
Soft-start Time (tSTART)
Reference Voltage
(VREF)
Lx Voltage
(VLX)
Output Voltage
(VOUT)
tSTARTUP_delay
19
RM590L
No.EA-592-210906
TECHNICAL NOTES
The performance of a power source circuit using this device is highly dependent on a peripheral circuit. A
peripheral component or the device mounted on PCB should not exceed its rated voltage, rated current or
rated power. When designing a peripheral circuit, please be fully aware of the following points.
•
Set the external components as close as possible to the IC and minimize the wiring between the
components and the IC. Especially, place a capacitor (CIN) as close as possible to the VIN pin and GND.
•
Ensure the VIN and GND lines are sufficiently robust. If their impedance is too high, noise pickup or
unstable operation may result.
•
A large switching current flows through the VIN line, GND line, VOUT line, inductor, LX, L1 and L2. Make
the wirings short and wide.
•
For any setting type of output voltage, the input/output voltage ratio must meet the following requirement
to achieve a stable VFM mode at light load when the MODE pin is "Low" (at PWM/VFM Auto Switching) :
VOUT / VIN < 0.7
VMODE = "Low", PWM / VFM Auto Switching
Input Voltage VIN (V)
5.5
Adjustable Output
4.7
Fixed Output
Voltage Type
Voltage Type
3.9
3.1
2.3
0.6
1.2
1.8
2.4
3.0
3.6
4.2
Output Voltage VOUT (V)
Available Voltage Area with Stable VFM Mode
•
The thermal shutdown function is to prevent smoke and ignition of the IC, not to ensure the reliability of
the IC or to keep it below the absolute maximum rating. In addition, it is not effective against heat
generated when the IC is not operating normally, such as latch-up and overvoltage application.
•
Do not design with depending on the thermal shutdown function of this IC as the system protection. The
thermal shutdown function is designed for this IC.
•
ESD Control
Take appropriate precautions when handling this product or PCB included this product.
Ex.
・ Use of an antistatic wrist band
・ Use of an ionizer
20
RM590L
No.EA-592-210906
APPLICATION INFORMATION
Adjustable Output Voltage Setting (RM590L002C/D)
By connecting divider resistors (R1, R2) to the VFB pin, the set output voltage (VSET) can be set using the
following equation.
VSET = VFB × (R1 + R2) / R2
The reference voltage (VFB) of this IC is set to 0.6 V, and the accuracy of VFB and the output voltage setting
range are as follows.
VSET: 0.6V ≤ VSET ≤ 5.5 V
VFB : 0.6 V ± 9mV
Refer to the following table for the recommended values for R1, R2 and C1.
Set Output Voltage (VSET) vs. R1 / R2 / C1 (Adjustable Output Voltage Type)
VSET [V]
R1 [kΩ]
R2 [kΩ]
0. 6
0
220
0. 6 < VSET ≤ 0 .9
220
0. 9 < VSET ≤ 1 .8
220
1. 8 < VSET ≤ 2 .1
150
2. 1 < VSET ≤ 2 .4
R1 = (VSET / VFB -1) x R2
100
2. 4 < VSET ≤ 2 .7
68
2. 7 < VSET ≤ 3 .0
47
3. 0 < VSET ≤ VIN
47
C1 [pF]
Open
47
33
10
10
10
10
6.8
21
RM590L
No.EA-592-210906
PCB Layout
RM590L (QFN2220-8) Board Diagram
Top Layer
Bottom Layer
22
RM590L
No.EA-592-210906
TYPICAL CHARACTERISTICS
Note: Typical Characteristics are intended to be used as reference data; they are not guaranteed.
1) Efficiency vs. Output Current
VOUT=0.9V
VOUT=1.2V
100
100
90
90
VFM / PWM Auto
70
70
60
60
50
VIN"2.7V"
= 2.7V
VIN"3.6V"
= 3.6V
VIN"4.2V"
= 4.2V
VIN"5.0V"
= 5.0V
40
30
20
VFM / PWM Auto
80
Efficiency η [%]
Efficiency η [%]
80
Forced PWM
VIN = 3.6V
10
VIN == 2.7V
VIN
2.7V
VIN == 3.6V
VIN
3.6V
VIN == 4.2V
VIN
4.2V
VIN == 5.0V
VIN
5.0V
50
40
30
20
10
0
0.01
0.1
1
10
100
0
0.01
1000
0.1
Output Current IOUT [mA]
1000
100
90
VFM / PWM Auto
80
80
70
70
60
Forced PWM
VIN = 3.6V
VIN ==2.7V
VIN
2.7V
VIN ==3.6V
VIN
3.6V
VIN ==4.2V
VIN
4.2V
VIN ==5.0V
VIN
5.0V
50
40
30
20
Efficiency η [%]
Efficiency η [%]
100
10
VOUT=3.3V
100
10
VFM / PWM Auto
Forced PWM
VIN = 4.2V
60
VIN
VIN = 4.2V
VIN = 5.0V
VIN
50
40
30
20
10
0
0.01
0.1
1
10
100
0
0.01
1000
2) Output Voltage vs. Output Current
VIN=3.6V, VOUT=1.8V
MODE = "H" Forced PWM Mode
1.82
1.82
Output Voltage VOUT [V]
1.83
1.81
1.80
1.79
1.78
1.77
100
200
300
Output Current IOUT [mA]
1
10
100
1000
VIN=3.6V, VOUT=1.8V
MODE = "L" PWM/VFM Auto Switching
1.83
0
0.1
Output Current IOUT [mA]
Output Current IOUT [mA]
Output Voltage VOUT [V]
1
Output Current IOUT [mA]
VOUT=1.8V
90
Forced PWM
VIN = 3.6V
400
1.81
1.80
1.79
1.78
1.77
0
100
200
300
400
Output Current IOUT [mA]
23
RM590L
No.EA-592-210906
3) Oscillator Frequency vs. Input Voltage
IOUT=1mA
MODE = "H" Forced PWM Mode
IOUT=1mA
MODE = "L" PWM/VFM Auto Switching
7
200
Frequency fosc [kHz]
Frequency fosc [MHz]
5
4
3
2
VOUT
= 0.9V
V
OUT = 0.9V
V
VOUT
1.2V
OUT ==1.2V
V
VOUT
1.8V
OUT ==1.8V
V
OUT ==3.3V
VOUT
3.3V
1
VOUT ==1.2V
1.2V
VOUT
160
VOUT ==1.8V
1.8V
VOUT
140
VOUT ==3.3V
3.3V
VOUT
120
100
80
60
40
20
0
0
2.0
2.5
3.0
3.5
4.0
4.5
Input Voltage VIN [V]
5.0
5.5
IOUT=200mA
MODE = "H" Forced PWM Mode
2.0
2.5
3.0
5.0
5.5
5.0
5.5
Frequency fosc [MHz]
7
6
5
4
3
2
6
5
4
3
2
VOUT
0.9V
V
OUT ==0.9V
V
VOUT
1.2V
OUT ==1.2V
V
VOUT
1.8V
OUT ==1.8V
V
VOUT
3.3V
OUT ==3.3V
1
VOUT == 0.9V
VOUT
0.9V
VOUT == 1.2V
VOUT
1.2V
VOUT == 1.8V
VOUT
1.8V
VOUT == 3.3V
VOUT
3.3V
1
0
0
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
2.0
2.5
3.0
Input Voltage VIN [V]
3.5
4.0
4.5
Input Voltage VIN [V]
4) Ripple Voltage vs. Input Voltage
VIN=3.6V, VOUT=1.8V
MODE = "H" Forced PWM Mode
VIN=3.6V, VOUT=1.8V
MODE = "L" PWM/VFM Auto Switching
50
50
45
45
IIout
1mA
OUT ==1mA
IIout
400mA
OUT ==400mA
40
35
Output Voltage Vripple [mV]
Output Voltage Vripple [mV]
3.5
4.0
4.5
Input Voltage VIN [V]
IOUT=200mA
MODE = "L" PWM/VFM Auto Switching
7
Frequency fosc [MHz]
VOUT
0.9V
VOUT ==0.9V
180
6
30
25
20
15
10
5
0
2
3
4
Input Voltage VIN [V]
5
6
Iout
IOUT =
= 1mA
IOUT = 400mA
Iout
40
35
30
25
20
15
10
5
0
2
3
4
5
6
Input Voltage VIN [V]
24
RM590L
No.EA-592-210906
VIN=3.6V, VOUT=1.8V, IOUT=1mA
MODE = "L" PWM/VFM Auto Switching
1.85
1.85
1.84
1.84
1.83
1.83
Output Voltage VOUT [V]
Output Voltage VOUT [V]
5) Output Voltage Waveform
VIN=3.6V, VOUT=1.8V, IOUT=1mA
MODE = "H" Forced PWM Mode
1.82
1.81
1.80
1.79
1.78
1.77
1.76
1.82
1.81
1.80
1.79
1.78
1.77
1.76
1.75
0.0
0.5
1.0
1.5
1.75
2.0
0
Time t [ms]
100
150
200
Time t [μs]
VIN=3.6V, VOUT=1.8V, IOUT=400mA
MODE = "H" Forced PWM Mode
VIN=3.6V, VOUT=1.8V, IOUT=400mA
MODE = "L" PWM/VFM Auto Switching
1.85
1.85
1.84
1.84
1.83
1.83
Output Voltage VOUT [V]
Output Voltage VOUT [V]
50
1.82
1.81
1.80
1.79
1.78
1.77
1.76
1.82
1.81
1.80
1.79
1.78
1.77
1.76
1.75
0.0
0.5
1.0
1.5
2.0
Time t [ms]
6) Ripple Voltage vs. Output Current
VIN=3.6V, VOUT=1.8V
MODE = "L" PWM/VFM Auto Switching, MODE = "H"
Forced PWM Mode
1.75
0.0
0.5
1.0
1.5
2.0
Time t [ms]
50
Output Voltage Vripple [mV]
45
Forced PWM
40
AUTO
35
30
25
20
15
10
5
0
0
50
100
150
200
250
300
350
400
Output Current IOUT [mA]
25
RM590L
No.EA-592-210906
7) Load Transient Response Waveform
VIN=3.6V, VOUT=1.8V, IOUT=1mA->200mA
MODE = "H" Forced PWM Mode
1.9
0
1.8
Output Voltage
1.7
100
Output Current
0
1.9
1.8
Output Voltage
1.7
1.6
1.6
100
200
300
0
400
100
Time t [μs]
400
100
1.9
0
1.8
Output Voltage
300
200
Output Voltage VOUT [V]
200
Output Current
Output Current IOUT [mA]
VIN=3.6V, VOUT=1.8V, IOUT=200mA->1mA
MODE = "L" PWM/VFM Auto Switching
300
Output Voltage VOUT [V]
300
Time t [μs]
VIN=3.6V, VOUT=1.8V, IOUT=1mA->200mA
MODE = "L" PWM/VFM Auto Switching
1.7
200
1.6
100
Output Current
1.9
0
1.8
Output Current IOUT [mA]
0
Output Voltage
1.7
1.6
0
100
200
300
400
0
200
Time t [μs]
2
1.9
0
1.8
Output Voltage
1.6
100
200
Time t [μs]
800
1000
300
400
6
4
Output Voltage VOUT [V]
MODE pin Voltage
MODE Pin Voltage [V]
4
0
600
MODE = "H" -＞ "L"
6
1.7
400
Time t [μs]
8) Mode Switching Waveform
VIN=3.6V, VOUT=1.8V, IOUT=1mA
MODE = "L" -＞ "H"
Output Voltage VOUT [V]
Output Current IOUT [mA]
100
200
2
MODE pin Voltage
1.9
0
MODE Pin Voltage [V]
Output Voltage VOUT [V]
200
Output Current
300
Output Voltage VOUT [V]
300
Output Current IOUT [mA]
VIN=3.6V, VOUT=1.8V, IOUT=200mA->1mA
MODE = "H" Forced PWM Mode
1.8
Output Voltage
1.7
1.6
0
200
400
600
800
1000
Time t [μs]
26
RM590L
No.EA-592-210906
Test Circuit
VIN
LX
VIN
CIN
MODE Control
VOUT
L1
L2
COUT
MODE
VOUT
RM590L
CE
GND
CE Control
RM590Lxx2A/B (Fixed Output Voltage Type)
VIN
LX
VIN
VOUT
L1
L2
R1
CIN
MODE Control
MODE
VFB
RM590L
CE
C1
COUT
R2
GND
CE Control
RM590L002C/D (Adjustable Output Voltage Type)
Components list for our evaluation
Symbol
Specification
Maximum Ratings
Model
CIN
4.7µF
6.3V
C1005X5R0J475M050BC
COUT
10uF
6.3V
GRM155R60J106ME44D
27
POWER DISSIPATION
QFN2220-8
PD-QFN2220-8(85125)-JE-A
The power dissipation of the package is dependent on PCB material, layout, and environmental conditions.
The following measurement conditions are based on JEDEC STD. 51.
Measurement Conditions
Item
Measurement Conditions
Environment
Mounting on Board (Wind Velocity = 0 m/s)
Board Material
Glass Cloth Epoxy Plastic (Four-Layer Board)
Board Dimensions
76.2 mm × 114.3 mm × 1.6 mm
Copper Ratio
Outer Layer (First Layer): More than 90% of 74.2 mm Square
Inner Layers (Second and Third Layers): Approx. 100% of 74.2 mm Square
Outer Layer (Fourth Layer): More than 90% of 74.2 mm Square
Through-holes
φ 0.3 mm × 4 pcs
Measurement Result
(Ta = 25°C, Tjmax = 125°C)
Item
Measurement Result
Power Dissipation
880 mW
Thermal Resistance (θja)
θja = 113°C/W
Thermal Characterization Parameter (ψjt)
ψjt = 55°C/W
θja: Junction-to-Ambient Thermal Resistance
ψjt: Junction-to-Top Thermal Characterization Parameter
76.2
74.2
1000
880
900
700
74.2
600
500
114.3
Power Dissipation (mW)
800
400
300
200
100
0
0
25
50
75
85
Ambient Temperature (°C)
100
Power Dissipation vs. Ambient Temperature
125
Measurement Board Pattern
i
PACKAGE DIMENSIONS
QFN2220-8
DM-QFN2220-8-JE-A
QFN2220-8 Package Dimensions
*
i
1. The products and the product specifications described in this document are subject to change or discontinuation of
production without notice for reasons such as improvement. Therefore, before deciding to use the products, please refer
to our sales representatives for the latest information thereon.
2. The materials in this document may not be copied or otherwise reproduced in whole or in part without prior written
consent of our company.
3. Please be sure to take any necessary formalities under relevant laws or regulations before exporting or otherwise
taking out of your country the products or the technical information described herein.
4. The technical information described in this document shows typical characteristics of and example application circuits
for the products. The release of such information is not to be construed as a warranty of or a grant of license under
our company's or any third party's intellectual property rights or any other rights.
5. The products listed in this document are intended and designed for use as general electronic components in standard
applications (office equipment, telecommunication equipment, measuring instruments, consumer electronic products,
amusement equipment etc.). Those customers intending to use a product in an application requiring extreme quality and
reliability, for example, in a highly specific application where the failure or misoperation of the product could result in
human injury or death (aircraft, spacevehicle, nuclear reactor control system, traffic control system, automotive and
transportation equipment, combustion equipment, safety devices, life support system etc.) should first contact us.
6. We are making our continuous effort to improve the quality and reliability of our products, but semiconductor products
are likely to fail with certain probability. In order to prevent any injury to persons or damages to property resulting from
such failure, customers should be careful enough to incorporate safety measures in their design, such as redundancy
feature, fire containment feature and fail-safe feature. We do not assume any liability or responsibility for any loss or
damage arising from misuse or inappropriate use of the products.
7. Anti-radiation design is not implemented in the products described in this document.
8. The X-ray exposure can influence functions and characteristics of the products. Confirm the product functions and
characteristics in the evaluation stage.
9. WLCSP products should be used in light shielded environments. The light exposure can influence functions and
characteristics of the products under operation or storage.
10. There can be variation in the marking when different AOI (Automated Optical Inspection) equipment is used. In the case
of recognizing the marking characteristic with AOI, please contact our sales or our distributor before attempting to use
AOI.
11. Please contact our sales representatives should you have any questions or comments concerning the products or
the technical information.
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