RT8058
1MHz, 2A, High Efficiency PWM Step-Down DC/DC Converter
General Description
The RT8058 is a current mode PWM step-down converter.
The chip is ideal for fixed frequency and low ripple
applications
over full range of load conditions. Its input
voltage range is from 2.6V to 5.5V with a constant 1MHz
switching frequency that allows it to adopt tiny, low cost
capacitors and inductors with 2mm or less in height making
it ideal for single-cell Li-lon/polymer battery applications.
The low on resistance internal MOSFET can achieve high
efficiency without the need of external schottky diodes in
wide operating ranges and the output voltage is adjustable
from 0.6V to 5V
that can provide up to 2A load current.
The RT8058 operates at 100% duty cycle for low dropout
operation that extends battery life in portable devices.
The RT8058 is available in a WQFN-16L 3x3 package.
Features
0.6V Reference Allows Low Output Voltage
Low Dropout Operation : 100% Duty Cycle
2A Load Current
<2μA Shutdown Current
μ
Up to 95% Efficiency
No Schottky Diode Required
1MHZ Constant Switching Frequency
Low R
DS(ON)
Internal Switches
Internally Compensated
Internal Soft-Start
Over temperature Protection
Short Circuit Protection
Small 16-Lead WQFN Package
RoHS Compliant and 100% Lead (Pb)-Free
Ordering Information
RT8058
Package Type
QW : WQFN-16L 3x3 (W-Type)
Lead Plating System
P : Pb Free
G : Green (Halogen Free and Pb Free)
Note :
Richtek products are :
RoHS compliant and compatible with the current require-
ments of IPC/JEDEC J-STD-020.
Suitable for use in SnPb or Pb-free soldering processes.
Applications
Portable Instruments
Microprocessors and DSP Core supplies
Cellular Telephones
Wireless and DSL Modems
Digital Cameras
PC Cards
Pin Configurations
(TOP VIEW)
NC
LX
16 15 14 13
LX
LX
12
Marking Information
For marking information, contact our sales representative
directly or through a Richtek distributor located in your
area.
PGND
PGND
PGND
FB
1
2
3
4
5
6
7
PVDD
PVDD
PVDD
VDD
PGND
17
8
11
10
9
WQFN-16L 3x3
DS8058-05 April 2011
GND
EN
NC
NC
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1
RT8058
Typical Application Circuit
RT8058
V
IN
2.6V to 5.5V
10,11,12
7
9
C
IN
10µF
PVDD
EN
VDD
GND
5
FB
4
R2
100k
LX
13,14,15
L1
3.3µH
R1
100k
C
OUT1
22µF
V
OUT
1.2V/2A
C
OUT2
22µF
PGND
1, 2, 3,
Exposed Pad (17)
Functional Pin Description
Pin No.
Pin Name
1, 2, 3
PGND
17 (Exposed Pad)
4
5
6, 8, 16
7
9
10, 11, 12
13, 14, 15
FB
GND
NC
EN
VDD
PVDD
LX
Pin Function
Power Ground. Connect this pin close to the (–) terminal of C
IN
and C
OUT
. The
exposed pad must be soldered to a large PCB and connected to PGND for
maximum power dissipation.
Feedback Input Pin. Receives the feedback voltage from a resistive divider
connected across the output.
Signal Ground. Return the feedback resistive dividers to this ground, which in turn
connects to PGND at one point.
No Internal Connection.
Enable pin. A logical high level at this pin enables the converter, while a logical
low level causes the converter to shut down.
Signal Input Supply. Decouple this pin to GND with a capacitor. Normally VDD is
equal to PVDD. Keep the voltage difference between VDD and PVDD less than
0.5V.
Power Input Supply of converter power stage. Decouple this pin to PGND with a
capacitor.
Internal Power MOSFET Switches Output of converter. Connect this pin to the
inductor.
Function Block Diagram
ISEN
OSC
Slope
Com
PVDD
0.6V
FB
EA
Output
Clamp
OC
Limit
Int-SS
0.3V
Control
Logic
OT
Driver
LX
PGND
VREF
POR
Temp-SEN
GND
VDD
EN
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2
DS8058-05 April 2011
RT8058
Absolute Maximum Ratings
(Note 1)
−0.3V
to 6V
−0.3V
to 6V
−0.3V
to 6V
1.471W
68°C/W
Supply Input Voltage VDD, PVDD -------------------------------------------------------------------------------------
LX Pin Switch Voltage ----------------------------------------------------------------------------------------------------
Other I/O Pin Voltage -----------------------------------------------------------------------------------------------------
Power Dissipation, P
D
@ T
A
= 25°C
WQFN-6L 3x3 --------------------------------------------------------------------------------------------------------------
Package Thermal Resistance (Note 2)
WQFN-16L 3x3,
θ
JA
-------------------------------------------------------------------------------------------------------
WQFN-16L 3x3,
θ
JC
------------------------------------------------------------------------------------------------------ 7°C/W
Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------------- 260°C
Storage Temperature Range --------------------------------------------------------------------------------------------
−
65°C to 150°C
Junction Temperature ----------------------------------------------------------------------------------------------------- 150°C
ESD Susceptibility (Note 3)
HBM (Human Body Mode) ---------------------------------------------------------------------------------------------- 2kV
MM (Machine Mode) ------------------------------------------------------------------------------------------------------ 200V
Recommended Operating Conditions
(Note 4)
Supply Input Voltage ------------------------------------------------------------------------------------------------------ 2.6V to 5.5V
Junction Temperature Range --------------------------------------------------------------------------------------------
−40°C
to 125°C
Ambient Temperature Range --------------------------------------------------------------------------------------------
−40°C
to 85°C
Electrical Characteristics
Parameter
Input Voltage Range
Feedback Voltage
DC Bias Current
(PVDD, VDD total)
Under voltage Lockout
Threshold
Oscillator Frequency
EN High-Level Input Voltage
EN Low-Level Input Voltage
Switch On Resistance, High
Switch On Resistance, Low
Peak Current Limit
Output Voltage Line Regulation
Output Voltage Load Regulation
V
IN
V
FB
(V
DD
= V
PVDD
= 3.6V, T
A
= 25°C, unless otherwise specified)
Symbol
Test Conditions
Min
2.6
0.582
Typ
--
0.6
3.4
340
--
2.43
150
1.0
--
--
142
96
3
0.05
0.15
Max
5.5
0.618
--
--
2
2.55
--
1.25
--
0.4
210
160
--
--
--
Unit
V
V
mA
μA
μA
V
mV
MHz
V
V
mΩ
mΩ
A
%/V
%/A
Active, No Load
Active, Not Switching, V
FB
= 0.5V
Shutdown, EN = 0
UVLO
f
OSC
V
EN_H
V
EN_L
R
DS(ON)_P
I
LIM
V
IN
= 2.6V to 5.5V
I
LOAD
= 0A 2A
I
OUT
= 200mA
R
DS(ON)_N
I
OUT
= 200mA
V
DD
Rising
V
DD
Hysteresis
Switching Frequency
--
--
--
2.3
--
0.75
1.4
--
--
--
2.2
--
--
DS8058-05 April 2011
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3
RT8058
Note 1.
Stresses listed as the above
“Absolute
Maximum Ratings” may cause permanent damage to the device. These are for
stress ratings. Functional operation of the device at these or any other conditions beyond those indicated in the
operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended
periods may remain possibility to affect device reliability.
Note 2.
θ
JA
is measured in the natural convection at T
A
= 25°C on a high effective four layers thermal conductivity test board of
JEDEC 51-7 thermal measurement standard. The case point of
θ
JC
is on the exposed pad of the package.
Note 3.
Devices are ESD sensitive. Handling precaution is recommended.
Note 4.
The device is not guaranteed to function outside its operating conditions.
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4
DS8058-05 April 2011
RT8058
Typical Operating Characteristics
Efficiency vs. Output Current
100
90
80
100
Efficiency vs. Output Current
90
80
V
IN
= 5V
V
IN
= 3.3V
V
IN
= 5V
V
IN
= 3.3V
Efficiency (%)
60
50
40
30
20
10
0
0
Efficiency (%)
V
OUT
= 1.8V, L = 3.3μH, C
OUT
= 22μFx2
500
1000
1500
2000
70
70
60
50
40
30
20
10
0
0
V
OUT
= 1.2V, L = 3.3μH, C
OUT
= 22μFx2
500
1000
1500
2000
Output Current (mA)
Output Current (mA)
Output Voltage vs. Outout Current
1.2000
1.1998
0.6010
0.6008
Reference Voltage vs. Input Voltage
1.1994
1.1992
1.1990
1.1988
1.1986
1.1984
1.1982
1.1980
0
250
V
IN
= 5V
Reference Voltage (V)
1.1996
0.6006
0.6004
0.6002
0.6000
0.5998
0.5996
0.5994
0.5992
0.5990
Output Voltage (V)
V
IN
= 3.3V
500
750
1000 1250 1500 1750 2000
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
Outout Current (mA)
Input Voltage (V)
Output Voltage vs. Temperature
1.205
1.203
1.201
Frequency vs. Temperature
1100
1050
Output Voltage (V)
1.199
1.197
1.195
1.193
1.191
1.189
1.187
1.185
-50
-25
0
25
50
75
Frequency (kHz)
1000
950
900
V
IN
= 3.6V
100
125
850
-50
-25
0
V
IN
= 3.6V, V
OUT
= 1.2V, I
OUT
= 0A
25
50
75
100
125
Temperature
(°C)
Temperature
(°C)
DS8058-05 April 2011
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5
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