HM1488B [HMSEMI]
High Efficiency Fast Response.5A, 30V Input Synchronous Step Down Regulator;
| 型号： | HM1488B |
| 厂家： | 
H&M Semiconductor |
| 描述： | High Efficiency Fast Response.5A, 30V Input Synchronous Step Down Regulator |
| 文件： | 总13页 (文件大小：1784K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
HM1488B
High Efficiency Fast Response.5A, 30V Input
Synchronous Step Down Regulator
General Description
HM1488B develops a high efficiency synchronous step-
Features
down DC-DC converter capable of delivering 5A
output current. HM1488B operates over a wide input
voltage range from 4.5V to 30V and integrates main
switch and synchronous switch with very low RDS(ON)
to minimize the conduction loss.
•
Low RDS(ON) for internal switches (top/bottom):
70/40 mΩ
•
•
4.5-30V input voltage range
Instant PWM architecture to achieve fast transient
responses
HM1488B adopts the instant PWM architecture to
achieve fast transient responses for high step down
applications and high efficiency at light loads. In
addition, it operates at pseudo-constant frequency of
500kHz under continuous conduction mode to
minimize the size of inductor and capacitor.
•
•
•
•
•
•
External softstart limits the inrush current
Pseudo-constant frequency: 500kHz at heavy loads
5A continuous, 6A peak load current capability
1.5% 0.6V reference
Output over current limit
Output short circuit protection with current fold
back
Ordering Information
□ □□ □
•
•
•
Thermal shutdown and auto recovery
RoHS Compliant and Halogen Free
Compact package: DFN3x4-12/SO8E
(
)
HM1488B
Temperature Code
Package Code
Optional Spec Code
Applications
Orering Number
HM1488BDRC
HM1488BESC
Package type
DFN4x3-12
SO8E
Note
--
--
•
•
•
•
•
•
LCD-TV
SetTop Box
Notebook
Storage
High power AP router
Networking
Typical Applications
Figure 1. Schematic Diagram Figure(HM1488BDRC)
HM1488B
Figure 2. Schematic Diagram Figure(HM1488BESC)
Efficiency vs. Load Current
100
95
90
85
80
75
VIN=12V,VOUT=5V
VIN=18V,VOUT=5V
VIN=30V,VOUT=5V
70
65
60
0.01
0.10
1.00
10.00
Load Current (A)
Figure 3. Efficiency vs. Load Current(HM1488BDRC)
Efficiency vs. Load Current
95
90
85
80
75
70
65
VIN=12V,VOUT=1.8V
60
VIN=18V,VOUT=1.8V
55
50
VIN=30V,VOUT=1.8V
0.01
0.10
1.00
10.00
Load Current (A)
Figure 4. Efficiency vs. Load Current(HM1488BESC)
HM1488B
Pinout (top view)
(DFN4x3-12)
(SO8E)
Top Mark: HM1488Bxyz for HM1488BDRC (Device code: HM1488B, x=year code, y=week code, z= lot number code)
HM1488Bxyz for HM1488BESC (Device code: HM1488B, x=year code, y=week code, z= lot number code)
Pin Name
BS
DFN4x3-12
SO8E
1
Pin Description
Boot-Strap Pin. Supply high side gate driver. Decouple this pin to LX pin
with 0.1uF ceramic cap.
1
Exposed
Paddle
10
Exposed Ground pin.
Paddle
GND
SVIN
PVIN
LX
7
8
2
Analog supply input. Bypass a 1uF capacitor to ground.
Power supply input. Decouple this pin to GND pin with at least 10uF
ceramic cap
Inductor pin. Connect this pin to the switching node of inductor
Enable control. The device has an accurate 1.2V rising threshold that will
allow the user to program the accurate turn-on delay by adding RC before
the EN pin.
11,12
2,3,4
EN
5
3
Internal 3.3V LDO output. Power supply for internal analog circuits and
driving circuit. Add a 1uF bypass capacitor to GND.
Power good Indicator. Low output if the output is within 90% of
regulation voltage; Open drain output otherwise.
VCC
PG
9
6
6
/
Output Feedback Pin. Connect this pin to the center point of the output
resistor divider (as shown in Figure 1) to program the output voltage:
Vout=0.6*(1+R1/R2)
Softstart programming pin. Connect a capacitor from this pin to ground
to program the softstart time. Tss=Css*0.6V/10uA
FB
SS
7
8
5
4
HM1488B
Absolute Maximum Ratings (Note 1)
PVIN, SVIN, LX, BS, EN, PG ----------------------------------------------------------------------------------------------- 33V
VCC,FB, SS, BS-LX ------------------------------------------------------------------------------------------- 4V
Power Dissipation, PD @ TA = 25°C DFN4X3-12/SO8E ------------------------------------------------------------ 2.8/3.3W
Package Thermal Resistance (Note 2)
θ
θ
JA ------------------------------------------------------------------------------------------------------------- 36/30°C/W
JC ------------------------------------------------------------------------------------------------------------ 18°/10°C/W
Junction Temperature Range ------------------------------------------------------------------------------------------------ 150°C
Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------------------ 260°C
Storage Temperature Range -------------------------------------------------------------------------------------- -65°C to 150°C
Dynamic LX voltage in 10ns duration-----------------------------------------------------------------------IN+3V to GND-4V
Recommended Operating Conditions (Note 3)
Supply Input Voltage -------------------------------------------------------------------------------------------------- 4.5V to 30V
Junction Temperature Range ------------------------------------------------------------------------------------- -40°C to 125°C
Ambient Temperature Range -------------------------------------------------------------------------------------- -40°C to 85°C
Function Block
PVIN
SVIN
Internal
Input
LDO 3.3V
UVLO 4V
BS
LX
VCC
EN
PWM Control
& Protect Logic
1.2V
0.6V
FB
PG
Thermal
Protect
Current
Sense
SS
GND
HM1488B
Electrical Characteristics
(VIN = 12V, VOUT = 5V, COUT = 47uF, TA = 25°C, IOUT = 1A unless otherwise specified)
Parameter
Symbol
VIN
IQ
ISHDN
VREF
Test Conditions
Min
4.5
Typ
Max
30
Unit
V
µA
µA
V
Input Voltage Range
Quiescent Current
Shutdown Current
Feedback Reference
Voltage
FB Input Current
Top FET RON
Bottom FET RON
Bottom FET Current
Limit
IOUT=0, VFB=VREF*105%
EN=0
200
5
0.6
10
0.609
0.591
-50
IFB
VFB=VCC
50
nA
mΩ
mΩ
A
Rds(on)1
Rds(on)2
ILIM
70
40
5
EN falling threshold
EN threshold hysteresis
Input UVLO threshold
UVLO hysteresis
Oscillator Frequency
Min ON Time
Min OFF Time
Internal LDO Output
Thermal Shutdown
Temperature
VENL
1.1
1.2
0.1
1.3
4
V
V
V
V
kHz
ns
ns
V
VEN,HYS
VUVLO
VHYS
0.2
500
80
120
3.3
160
FOSC
IOUT=200mA
VIN=4V
VVCC
TSD
3.2
3.4
°C
Thermal Shutdown
Hysteresis
TSD,HYS
20
°C
Note 1: Stresses beyond the “Absolute Maximum Ratings” may cause permanent damage to the device. These are
stress ratings only. Functional operation of the device at these or any other conditions beyond those indicated in the
operational sections of the specification is not implied. Exposure to absolute maximum rating conditions for
extended periods may affect device reliability.
Note 2:
θJA is measured in the natural convection at TA = 25°C on a low effective single layer thermal conductivity
test board of JEDEC 51-3 thermal measurement standard. Paddle of DFN3x3-12/SO8E packages is the case position
for θJC measurement.
Note 3: The device is not guaranteed to function outside its operating conditions.
HM1488B
Typical Performance Characteristics
Efficiency vs. Load Current
95
90
85
80
75
70
65
VIN=5V,VOUT=1.8V
VIN=12V,VOUT=1.8V
VIN=18V,VOUT=1.8V
VIN=30V,VOUT=1.8V
60
55
50
0.01
0.10
1.00
10.00
Load Current (A)
Efficiency vs. Load Current
Efficiency vs. Load Current
100
95
100
95
90
85
90
85
80
75
80
75
VIN=5V,VOUT=3.3V
VIN=12V,VOUT=5V
VIN=18V,VOUT=5V
VIN=30V,VOUT=5V
70
70
65
60
VIN=12V,VOUT=3.3V
VIN=18V,VOUT=3.3V
VIN=30V,VOUT=3.3V
65
60
0.01
0.10
1.00
10.00
0.01
0.10
1.00
10.00
Load Current (A)
Load Current (A)
Load Transient
Output Ripple
(VIN=12V, VOUT=5V, ILOAD=2.5-5A)
(VIN=12V,VOUT=5V, ILOAD=5A)
VOUT(AC)
0.2V/div
2A/div
VOUT(AC)
20mV/div
10V/div
VLX
IL
IL
5A/div
Time (200ꢀs/div)
Time (1ꢀs/div)
HM1488B
Shutdown
(EN=10Hz,VIN=12V, VOUT=5V, ILOAD=5A)
EN
5V/div
VLX
10V/div
VOUT
IL
5V/div
5A/div
Time (400µs/div)
Short Circuit Protection
(VIN=12V, VOUT=5V, Null load to Short)
VOUT
5V/div
2A/div
IL
Time (1ms/div)
HM1488B
Operation
PVIN/GND pins. In this case, a 10uF low ESR ceramic
capacitor is recommended.
HM1488B is a synchronous buck regulator IC that
integrates the PWM control, top and bottom switches
on the same die to minimize the switching transition
loss and conduction loss. With ultra low Rds(on) power
switches and proprietary PWM control, this regulator
IC can achieve the highest efficiency and the highest
switch frequency simultaneously to minimize the
external inductor and capacitor size, and thus achieving
the minimum solution footprint.
The internal analog circuit is powered from SVIN. To
avoid the noise issue, a 1uF ceramic capacitor
connected closely from SVIN to GND is recommended.
An RC filter can also be added from power input to
SVIN.
HM1488B provides protection functions such as cycle by
cycle current limiting and thermal shutdown protection.
HM1488B will sense the output voltage conditions for the
fault protection.
Output capacitor COUT:
The output capacitor is selected to handle the output
ripple noise requirements. Both steady state ripple and
transient requirements must be taken into consideration
when selecting this capacitor. For the best performance,
it is recommended to use X5R or better grade ceramic
capacitor greater than 47uF capacitance.
Applications Information
Because of the high integration in the HM1488B IC, the
application circuit based on this regulator IC is rather
simple. Only input capacitor CIN, output capacitor COUT,
output inductor L and feedback resistors (R1 and R2)
need to be selected for the targeted applications
specifications.
Output inductor L:
There are several considerations in choosing this
inductor.
Feedback resistor dividers R1 and R2:
1) Choose the inductance to provide the desired
ripple current. It is suggested to choose the ripple
current to be about 40% of the maximum output
current. The inductance is calculated as:
Choose R and R2 to program the proper output voltage.
1
To minimize the power consumption under light loads,
it is desirable to choose large resistance values for both
R1 and R2. A value of between 10kΩ and 1MΩ is
highly recommended for both resistors. If Vout is 3.3V,
R1=100k is chosen, then using following equation, R2
VOUT (1− VOUT/VIN,MAX
)
L =
FSW × IOUT,MAX × 40%
can be calculated to be 22.1k:
VOUT
where Fsw is the switching frequency and IOUT,MAX is
the maximum load current.
0.6V
R2 =
R1 .
R1
0.6VFB
GND
The HM1488B regulator IC is quite tolerant of different
ripple current amplitude. Consequently, the final choice
of inductance can be slightly off the calculation value
without significantly impacting the performance.
2) The saturation current rating of the inductor must
be selected to be greater than the peak inductor
current under full load conditions.
VOUT − 0.6V
R2
Input capacitor CIN:
The ripple current through input capacitor is calculated
as：
V
OUT(1-VOUT/VIN
,MAX)
.
ICIN _ RMS = IOUT D(1− D)
ISAT
,
MIN > IOUT
,
MAX
+
2 FSW
L
To minimize the potential noise problem, place a
typical X5R or better grade ceramic capacitor really
close to the PVIN and GND pins. Care should be taken
to minimize the loop area formed by CIN, and
3) The DCR of the inductor and the core loss at the
switching frequency must be low enough to
achieve the desired efficiency requirement. It is
HM1488B
desirable to choose an inductor with DCR<10mΩ
to achieve a good overall efficiency.
may further speed up the load transient responses.
Soft-start
Connect a capacitor from softstart programming pin to
ground to program the softstart time.
Tss=Css*0.6V/10uA
Enable Operation
A 1kΩ RFF is recommended .The selection of CFF is
related to the output capacitance.Refer to the follow
table for proper CFF value.
Pulling the EN pin low (<1.2V) will shut down the
device. During shutdown mode, the HM1488B
shutdown current drops to lower than 5uA, Driving the
EN pin high (>1.3V) will turn on the IC again.
COUT(uF)
47
CFF(nF)
0.1
External Bootstrap Cap
This capacitor provides the gate driver voltage for
internal high side MOSEFET. A 100nF low ESR
ceramic capacitor connected between BS pin and LX
100
0.68
1
220
330
3.3
pin is recommended.
BS
470
6.8
CBS
100nF
680
10
LX
1000
47
Layout Design:
The layout design of HM1488B regulator is relatively
simple. For the best efficiency and minimum noise
problem, we should place the following components
close to the IC: CIN, CVCC L, R1 and R2.
1) It is desirable to maximize the PCB copper area
connecting to GND pin to achieve the best thermal and
noise performance. If the board space allowed, a
ground plane is highly desirable.
VCC LDO
The 3.3V internal reference. This pin should be
bypassed to ground with a 1uf ceramic capacitor. This
pin may be used with an external DC load of 20mA or
less
2) CIN must be close to IN and GND pins. The loop
area formed by CIN and GND must be minimized.
.
Power Good Indication
PG is an open-drain output pin. This pin will pull to
ground if output voltage is lower than 90% of
regulation voltage. Otherwise this pin will go to a high
impedance state.
3) The PCB copper area associated with LX pin must
be minimized to avoid the potential noise problem.
4) The components R1 and R2, and the trace connecting
to the FB pin must NOT be adjacent to the LX net on
the PCB layout to avoid the noise problem.
Feed forward capacitor CFF:
The HM1488B regulator IC adopts the instant PWM
architecture to achieve good stability and fast transient
responses. In applications with high step load current,
adding an RC network RFF and CFF parallel with R1
5) If the system chip interfacing with the EN pin has a
high impedance state at shutdown mode and the IN pin
is connected directly to a power source such as a Li-Ion
battery, it is desirable to add a pull down 1Mohm
resistor between the EN and GND pins to prevent the
noise from falsely turning on the regulator at shutdown
mode.
HM1488B
DFN4x3-12 Package outline & PCB Layout
Top View
Bottom View
Side View
PCB layout (Recommended)
Notes:
All dimension in MM and exclude mold flash & metal burr
SO8E Package outline & PCB layout design
HM1488B
1.27 TYP
3.20
0.30 – 0.50
0.60
Recommended Pad Layout
4
0.25 - 0.50
5
4.80 - 5.00
°
0.60 - 0.85
1.27 (TYP)
Notes: All dimensions are in millimeters.
All dimensions don’t include mold flash & metal burr.
HM1488B
Taping & Reel Specification
1. Taping orientation
SOP8-EP
3.9/4.1
1.45/1.55
Feeding direction
DFN4x3 (DFN4030)
Feeding direction
HM1488B
2.Carrier Tape & Reel specification for packages
Package
types
Tape width
(mm)
Pocket
pitch(mm)
Reel size
(Inch)
Reel
Trailer
Leader length Qty per
width(mm) length(mm)
(mm)
reel
SOP8E
12
12
8
8
13"
13"
12.4
12.4
400
400
400
400
2500
5000
DFN4x3
2. Others: NA
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