BL8541

BL8541
0.9V startup, 1A True Shut-Off Synchronous Boost DC/DC converter
DESCRIPTION
FEATURES
The BL8541, is a high-efficiency, synchronous stepup switching regulators optimized for batterypowered applications. It supports up to 1A load
current and allows the use of small, low cost
inductors and MLCC capacitors.
The BL8541 starts up as low as 0.9V input voltage
and it has true-shutoff function (shut off output to
zero voltage when CE pulled low) and real output
short-circuit protection. These features make it
ideal for USB interface power supply.
Given its high efficiency, the BL8541 device is ideal
for small portable applications powered by battery.
It consumes as low as 40uA (3V input /3.3V output)
at zero load. And its current consumption is less
than 1uA in shutdown mode.
BL8541 is available in DFN2x2-6 package.
TYPICAL APPLICATION
Capable of Delivering 1A
High Efficiency: Up to 92%
Compatible with MLCC capacitor
1.8MHz Switching Frequency
Low dropout 100% Duty operation
0.6V Reference for Low Output voltages
True Shutoff and Short-Circuit Protection
Logic Control Shutdown (IQ<1uA)
Thermal shutdown and UVLO
Available in DFN2x2-6
APPLICATIONS





MID / Tablet PC
Portable Power Bank
Smartphone OTG
Toy
Other portable device
PIN OUT & MARKING
*Needed, when
Vout>=4.5V
6.8uH










1
CE
2
FB
1nF*
VIN
LX
VOUT
VIN
BL8541
LC3403
22uF
FB
CE
www.belling.com.cn
3 VOUT
6
LX
5
GND
4
VOUT
4.7uF
OFF ON
AL
YW
VIN
DFN2x2-6
Top View
GND
AL: Product Code
YW: Date code (Year & Week)
1
BL8541
ORDERING INFORMATION
PART No.
BL8541CKCTR
PACKAGE
DFN2x2-6
Tape&Reel
3000/Reel
ABSOLUTE MAXIMUM RATING
Parameter
Value
Max Input Voltage
Max Operating Junction Temperature(Tj)
Ambient Temperature(Ta)
Maximum Power Dissipation
DFN2x2-6
Storage Temperature(Ts)
Lead Temperature & Time
ESD (HBM)
5.5V
125C
-40C – 85C
800mW
-55C - 150C
260C, 10S
>2000V
Note: Exceed these limits to damage to the device. Exposure to absolute maximum rating conditions may affect
device reliability.
RECOMMENDED WORK CONDITIONS
Parameter
Value
Input Voltage Range
Operating Junction Temperature(Tj)
Max. 5V
-40C – 85C
ELECTRICAL CHARACTERISTICS
(VDD=5V, TA=25C)
Symbol
VDD
Vstart
Vref
Ifb
Vout
Iq
Parameter
Conditions
Input Voltage Range
Min
Max
Unit
5
V
0.9
1.0
V
0.6
0.615
V
0.1
0.4
uA
5
V
0.9
Startup Voltage
Iout = 0 A
Feedback Voltage
Vout = 2.5 to 5V
0.585
Feedback Leakage current
Output Voltage Range
Quiescent Current
Typ
2.1
Active, Vfb=0.7, No Switching
40
60
uA
Shutdown
1
10
uA
5
uA
Irev
Reverse current, Vout to Vin
Fsoc
Switching Frequency
1.8
RdsonP
PMOS Rdson
150
300
mohm
RdsonN
NMOS Rdson
150
300
mohm
1.5
2
A
10
uA
1
uA
Ilimit
Peak Current Limit
Ilxlk
LX Leakage Current
Icelk
CE Leakage Current
Vh_en
EN Input High Voltage
Vl_en
EN Input Low Voltage
TSD
CE=0
1.2
LX=5V, CE=0
0.6
V
0.3
Thermal Shut Down
www.belling.com.cn
MHz
150
2
V
C
BL8541
PIN DESCRIPTION
PIN #
1
NAME
CE
2
FB
3
4
5
6
VOUT
GND
LX
VIN
DESCRIPTION
Enable pin for the IC. Drive the pin to high to enable the part, and low to disable
Feedback input. Connect an external resistor divider from the output to FB and
GND to set the output to a voltage between 0.6V and Vin
Output voltage pin, with 22uF ceramic capacitor closely connected to GND
Ground
To connect inductor to VIN
Supply voltage, with 4.7uF ceramic capacitor connected to GND
ELECTRICAL PERFORMANCE
Tested under TA=25C, L=6.8uH, unless otherwise specified
www.belling.com.cn
3
BL8541
Output Ripple / LX / Inductor Current
Vin=3.6V, Vout=5V, Iout=0.5A
Output Short Circuit Protection
Vin=3.6V / Vout set to 5V
BLOCK DIAGRAM
CE
VOUT
VIN
UVLO &
Thermal
shutdown
REF
+
EA
+
COMP
network
Σ
-
FB
PWM
Logic
LX
DRIVER
OSC
Slope Comp
GND
www.belling.com.cn
4
BL8541
DETAILED DESCRIPTION
General description
The BL8541 is a high-efficiency, Boost DC/DC converter, with input current limit at 1.5A. It integrates an
150mΩ high side MOSFET and an 150 mΩ low side MOSFET. It employs PWM/PFM auto-switch control mode.
Short circuit protection
BL8541 employs a “Hiccup” mode of short-circuit protection, which enables output voltage auto recover
when short-circuit is removed.
True shut off function
BL8541 offers a true shut off function, which means it can really shut off output (make output voltage to zero)
when CE is pull low (chip turns off). Normally, there is a schottky diode (or MOSFET body diode) existed
between LX and Vout for a normal boost converter, and thus, when CE is pull low, though the chip is turned
off, the Vin is connected to Vout thru inductor and schottky diode. So we still can detect a voltage at Vout
terminal. BL8541, with its proprietary design skill, can truly shut down the output when chip is turned off.
Design Procedure
Setting Output Voltages
Output voltages are set by external resistors. The FB_ threshold is 0.6V.
RTOP = RBOTTOM[(VOUT / 0.6) - 1]
Capacitor Selection
A 22uF ceramic capacitor is demanded on output terminal, while 4.7uF is good enough for input.
Higher values, lower cost ceramic capacitors are now becoming available in smaller case sizes. Their high
ripple current, high voltage rating and low ESR make them ideal for switching regulator applications. Using
ceramic capacitors can achieve very low output ripple and small circuit size. When choosing the input and
output ceramic capacitors, choose the X5R or X7R dielectric formulations. These dielectrics have the best
temperature and voltage characteristics of all the ceramics for a given value and size.
Application Information
Layout is critical to achieve clean and stable operation. The switching power stage requires particular
attention. Follow these guidelines for good PC board layout:
1) Place 22uF output capacitors as close to the IC VOUT and GND pins as possible
2) Connect input and output capacitors to the same power ground node with a star ground configuration
then to IC ground.
3) Keep the high-current paths as short and wide as possible. Keep the path of switching current short.
Avoid vias in the switching paths.
4) If possible, connect VIN, LX, and GND separately to a large copper area to help cool the IC to further
improve efficiency and long-term reliability.
5) Ensure all feedback connections are short and direct. Place the feedback resistors as close to the IC as
possible.
6) Route high-speed switching nodes away from sensitive analog areas
www.belling.com.cn
5
BL8541
PACKAGE OUTLINE
Package
DFN2x2-6
Devices per reel
Package specification：
www.belling.com.cn
6
3000
Unit
mm