Ordering number : ENA1843
Bi-CMOS IC
LV5857MX
Step-down Switching Regulator
Overview
LV5857MX is a 1ch step-down switching regulator. With built-in two 0.13Ω power MOSFET switch, it achieves high
output current and high efficiency. With low-heat resistance, miniature package MFP8 (200mil) with heat-sink is adopted.
Since it is Current mode control type, it has good load current response, and phase compensation is easy. With ON/OFF pin,
operating can be less than 60μA at stand-by mode. It has cycle-by-cycle over current protection for load devices. With
external capacitor, it achieves soft start.
Functions
• 3A 1ch step-down
• Small package: MFP8 (200mil) with heat sink
• High efficiency (93% IOUT = 1A, VIN = 12V, VO = 5V)
• Standby mode
• Over-current protection(Latch off method)
• Thermal shutdown protection
• Reference voltage: 0.672V
• Fixed frequency: 340kHz
• Soft start / Soft stop
Specifications
Maximum Ratings at Ta = 25°C
Parameter
Symbol
Conditions
Ratings
Unit
Maximum input VIN voltage
VIN max
20
V
BOOT pin maximum voltage
VBT max
25
V
SW pin maximum voltage
VSW max
VIN max
V
BOOT pin-SW pin maximum voltage
VBS-SW max
EN Maximum Voltage
VEN max
7
V
20
V
FB, COMP, SS pin maximum voltage
Vfs max
Allowable power dissipation
Pd max
Junction temperature
Tj max
150
°C
Operating temperature
Topr
-20 to 80
°C
Storage temperature
Tstg
-40 to 150
°C
Mount on a specified board *
7
V
2.05
W
Specified substrate : 46.0mm х 32.0mm х 1.6mm glass epoxy substrate.
Note: Plan the maximum voltage while including coil and surge voltages, so that the maximum voltage is not exceeded even for an instant.
Any and all SANYO Semiconductor Co.,Ltd. products described or contained herein are, with regard to
"standard application", intended for the use as general electronics equipment (home appliances, AV equipment,
communication device, office equipment, industrial equipment etc.). The products mentioned herein shall not be
intended for use for any "special application" (medical equipment whose purpose is to sustain life, aerospace
instrument, nuclear control device, burning appliances, transportation machine, traffic signal system, safety
equipment etc.) that shall require extremely high level of reliability and can directly threaten human lives in case
of failure or malfunction of the product or may cause harm to human bodies, nor shall they grant any guarantee
thereof. If you should intend to use our products for applications outside the standard applications of our
customer who is considering such use and/or outside the scope of our intended standard applications, please
consult with us prior to the intended use. If there is no consultation or inquiry before the intended use, our
customer shall be solely responsible for the use.
Specifications of any and all SANYO Semiconductor Co.,Ltd. products described or contained herein stipulate
the performance, characteristics, and functions of the described products in the independent state, and are not
guarantees of the performance, characteristics, and functions of the described products as mounted in the
customer' s products or equipment. To verify symptoms and states that cannot be evaluated in an independent
device, the customer should always evaluate and test devices mounted in the customer' s products or
equipment.
92910 SY 20100915-S00003 No.A1843-1/5
LV5857MX
Recommended Operating Conditions at Ta = 25°C
Parameter
Symbol
Conditions
Ratings
Unit
VIN pin voltage
VIN
8 to 18
BOOT pin voltage
VBT
-0.3 to 23
V
V
SW pin voltage
VSW
-0.4 to VIN
V
BOOT pin-SW pin voltage
VBS-SW
6.5
V
EN voltage
VEN
18
V
FB, COMP, SS pin voltage
VFSO
6
V
Electrical Characteristics at Ta = 25°C, VIN = 12V, unless otherwise specified.
Parameter
Symbol
Conditions
Ratings
min
typ
Unit
max
IC current drain at standby
ICC1
EN=0V
60
μA
IC current drain in operation
ICC2
EN=5v, FB=1V
2.5
mA
Efficiency
Effcy
VIN=12V, IOUT=1A, Vo=5V, Design target *2
93
Reference voltage
Vref
VIN=8V to 28V
FB pin bias current
Iref
FB=0.672V
High-side ON resistance
RonH
BOOT=5V, IOUT=1A
Low-side ON resistance
-2%
%
0.672
+2%
V
10
100
nA
0.13
Ω
RonL
0.13
Ω
Oscillation frequency
fOSC
340
kHz
EN high-threshold voltage
Venth
1.5
Maximum ON DUTY
D max
Minimum ON DUTY
D min
SW Peak Current limit
Icl1
VIN=12V, VOUT=5V, L=10μH
Thermal shutdown temperature
Ttsd
*Design guarantee *3
160
°C
Thermal shutdown temperature
Dtsd
*Design guarantee *3
40
°C
Soft start current
ISS
SS=0V
6
μA
Discharge On-Resistance
VSWON
35
Ω
VIN UVLO lock voltage
VUVLOL
6.0
V
VIN UVLO lock release voltage
VUVLOH
6.9
V
V
80
%
8
4
%
A
hysteresis
*2: Reference value (not tested before shipment)
*2: Design guarantee (value guaranteed by design and not tested before shipment)
No.A1843-2/5
LV5857MX
Package Dimensions
unit : mm (typ)
3372
Pd max -- Ta
2.5
SIDE VIEW
BOTTOM VIEW
5.0
Allowable power dissipation, Pd max -- W
TOP VIEW
(3.4)
(2.6)
0.43
6.0
4.4
8
1
2
0.35
(0.65)
0.15
1.5
1.15
1.0
0.5
0
-20
0
20
40
60
80
100
Ambient temperature, Ta -- ∞C
0.05
(1.5)
SIDE VIEW
1.7 MAX
1.27
2.05
2.0
SANYO : MFP8(200mil)
Pin Assignment
BOOT 1
8 SS
VIN 2
7 EN
SW 3
6 COMP
GND 4
5 FB
Top view
Block Diagram and Sample Application Circuit
BOOT (SW + Vreg.)
BOOT
VIN
Current Sense
Amp.
+
Rb
Pre-Drive
UVLO
FB
1:N
OSC
340kHz
+
-
Error
Amp.
+
PWM
comparator
GND
C4=OPEN
-30%
SS
EN
H : ON
VOUT
Pre-Drive
COMP
C3
SW
Internal Stable
supply
Vref
0.672V
+20%
+
+
-
EN
UVLO
TSD
UVP
OVP
Current
Limit
VIN
TSD
Soft-Stop
Internal
Regulator Internal Regulator
(5V)
L : OFF
C1,C2,C5,C8,C9=Ceramic capacitor
No.A1843-3/5
LV5857MX
Pin Function
Pin No.
1
Pin name
BOOT
2
VIN
3
SW
Function
Equivalent circuit
Upper MOS transistor boot strap capacitance connection pin.
Connect the boot capacitance of about 0.1uF between SW pins.
To protect the SW pin’s absolute maximum rating , to ensure
stable
operation, and to eliminate noise , the boot capacitance serial
resistance (about 15Ω) Rb proves effective.
Input Voltage Pin. Connect substantially large (10uF 1 piece or 2
parallel or more) capacitance between this pin and GND.
Power Switch pin.
Connect the output LC filter.
Connect the above capacitance between this pin and BOOT pin.
The discharge transistor for a Soft-Stop is connected with this
terminal (typcal 35Ω). It turns it on by either EN=L, UVLO or a
thermal shutdown.
4
GND
Ground pin.
5
FB
Feedback pin.
Set the output voltage by means of split resistor in the section of
the output voltage
VOUT-FB-GND. VOUT setting is made as calculated below.
VOUT = Vref × { 1 +
(R1 + R10)
}
R3
Vref = 0.672V
VIN
BOOT
High side MOS
SW
Low side MOS
Discharge
VIN
Example: 3.3V output voltage
(See, Block Diagram and Application example)
VOUT = 0.672 × { 1 +
8
SS
(22k + 3.9k)
}
10k
=3.353V
Soft start pin.
Sets the soft start time by means of the built-in 6μA source
voltage and external soft start capacity. The soft start capacity C6
can be set as follows:
SS
FB
Tss
C6 = 6μA × Vref
VREF
0.672V
Where, Tss is the soft start time and Vref is the reference
voltage.
Example:1.7ms soft start time achieved
1.7ms
C6 = 6μA × 0.672V = 0.015μF
6
COMP
Phase compensation pin.
Connects with the phase compensation external capacitance and
resistance of DC/DC converter close loop.
VIN
COMP
7
EN
Enable pin.
Converter enabled when set to the HIGH voltage and disabled
when LOW voltage or OPEN state.
VIN
EN
2pF
No.A1843-4/5
LV5857MX
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This catalog provides information as of September, 2010. Specifications and information herein are subject
to change without notice.
PS No.A1843-5/5