EM5812AGE [EXCELLIANCE]
12A 5V/12V Step-Down Converter;型号: | EM5812AGE |
厂家: | Excelliance MOS |
描述: | 12A 5V/12V Step-Down Converter |
文件: | 总10页 (文件大小:365K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
EM5812/A
12A 5V/12V Step-Down Converter
General Description
Applications
EM5812/A is a synchronous rectified PWM
controller with a built in high-side power MOSFET
operating with 5V or 12V supply voltage. It
achieves 10A continuous output current with
excellent load and line regulation. This device
operates at 200/300kHz and provides an optimal
level of integration to reduce size and cost of the
power supply.
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Notebook & Netbook
Graphic Cards & MB
Low Voltage Logic Supplies
Pin Configuration
This part includes internal soft start, internal
compensation networks, over current protection,
under voltage protection, and shutdown function.
This part is available in SOP-8 package.
Ordering Information
Part Number
EM5812GE
EM5812AGE
Package
SOP-8 EP
SOP-8 EP
Frequency
200kHz
300kHz
Typical Application Circuit
Features
ꢀ
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ꢀ
ꢀ
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ꢀ
ꢀ
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Operate from 5V to 12V Voltage Supply
15mΩ Internal Power MOSFET Switch
0.6V VREF with 1.5% Accuracy
Voltage Mode PWM Control
200/300kHz Fixed Frequency Oscillator
0% to 80% Duty Cycle
Internal Soft Start
Over Current Protection
Integrated Bootstrap Diode
Adaptive Non-Overlapping Gate Driver
Under Voltage Protection
Over Voltage Protection
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EM5812/A
Pin Assignment
Pin Name Pin No.
Pin Function
Lower Gate Driver Output. Connect this pin to the gate of lower MOSFET. This pin
is monitored by the adaptive shoot-through protection circuitry to determine when
the lower MOSFET has turn off.
LGATE
VCC
1
2
Bias Supply Voltage. This pin provides the bias supply for the EM5812/A and the
lower gate driver. The supply voltage is internally regulated to 5VDD for internal
control circuit. Connect a well-decoupled 4.5V to 13.2V supply voltage to this pin.
Ensure that a decoupling capacitor is placed near the IC.
Feedback Voltage. This pin is the inverting input to the error amplifier. A resistor
divider from the output to GND is used to set the regulation voltage.
FB
EN
3
4
Enable Pin. Pulling this pin lower than 0.3V disables the controller and causes the
oscillator to stop.
PHASE Switch Node. Connect this pin to the drain of the low-side MOSFET. This pin
is used as the source for the high-side MOSFET, and to monitor the voltage drop
across the low-side MOSFET for over current protection. This pin is also monitored
by the adaptive shoot-through protection circuitry to determine when the high-side
MOSFET has turned off. A Schottky diode between this pin and ground is
recommended to reduce negative transient voltage which is common in a power
supply system.
PHASE
5,6
VIN
EP
7
Input Supply Voltage. This supplies power to the high-side MOSFET.
Bootstrap Supply for the floating upper gate driver. Connect the bootstrap
capacitor C BOOT between BOOT pin and the PHASE pin to form a bootstrap circuit.
The bootstrap capacitor provides the charge to turn on the upper MOSFET. Typical
values for C BOOT range from 0.1uF to 0.47uF. Ensure that C BOOT is placed near the
IC.
BOOT
Signal and Power Ground for the IC. All voltages levels are measured with respect
to this pin. Tie this pin to the ground island/plane through the lowest impedance
connection available.
GND
8
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EM5812/A
Function Block Diagram
VCC
2
7
BOOT
Internal
regulator
EP
VIꢀ
Soft Start
POR
5,6
PHASE
OTP
-
-
Gate
control
logic
PWM
3
FB
EA
VOCP
+
Vref
Ramp
VCC
VCC
17V
Oscillator
1
8
LGATE
GꢀD
65% Vref
FB
Eꢀ
4
Enable
0.3V
FB
130% Vref
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EM5812/A
Absolute Maximum Ratings (Note 1)
ꢀ Supply voltage, VCC---------------------------------------------------------------- -0.3V to 16V
ꢀ Supply voltage, VIN---------------------------------------------------------------- -0.3V to 16V
ꢀ PHASE to GND
DC-------------------------------------------------------------------------------------- -5V to 16V
<200ns-------------------------------------------------------------------------------- -10V to 32V
ꢀ BOOT to PHASE--------------------------------------------------------------------- 16V
ꢀ BOOT to GND
DC-------------------------------------------------------------------------------------- -0.3V to PHASE+16V
<200ns-------------------------------------------------------------------------------- -0.3V to 42V
ꢀ LGATE
DC-------------------------------------------------------------------------------
<200ns-------------------------------------------------------------------------
-0.3V to VCC + 0.3V
-5V to VCC+5V
ꢀ EN & FB------------------------------------------------------------------------------- -0.3V to 6V
ꢀ Power Dissipation, PD @ TA = 25°C,
PSOP-8 ------------------------------------------------------------------------------- 1.33W
ꢀ Package Thermal Resistance, ΘJA,
PSOP-8 (Note 2) ------------------------------------------------------------------------------- 75°C/W
ꢀ Junction Temperature------------------------------------------------------------- 150°C
ꢀ Lead Temperature (Soldering, 10 sec.)---------------------------------------- 260°C
ꢀ Storage Temperature Range----------------------------------------------------- -65°C to 150°C
ꢀ ESD susceptibility (Note3)
HBM (Human Body Mode)------------------------------------------------------- 2KV
MM (Machine Mode)-------------------------------------------------------------- 200V
Recommended Operating Conditions (Note4)
ꢀ Supply Voltage, VCC ------------------------------------------------------------ 4.5V to 13.2V
ꢀ Supply Voltage, VIN ------------------------------------------------------------ 2.5V to 13.2V
ꢀ Junction Temperature ------------------------------------------------------- -40°C to 125°C
ꢀ Ambient Temperature ------------------------------------------------------ -40°C to 85°C
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EM5812/A
Electrical Characteristics
VCC=12V, TA=25℃, unless otherwise specified
Parameter Symbol
VCC Supply Section
Test Conditions
Min Typ
Max Units
VCC Supply Voltage
VCC
4.5
4
13.2
4.4
V
mA
mA
V
Supply Current
ICC
ICCQ
LGATE open, Switching.
No Switching.
10
2
Quiescent Supply Current
VCC Power on Reset Threshold
VCC Power on Reset Hysteresis
VIN Supply Section
VCCRTH
VCCHYS
4.2
0.2
V
VIN Power on Reset Threshold
VINTH
1.5
V
Internal Oscillator
EM5812
170 200 230
255 300 345
1
KHz
KHz
Vp-p
Free Running Frequency
FSW
EM5812A
Ramp Amplitude
△VOSC
Error Amplifier
Open Loop DC Gain
Gain-Bandwidth Product
Slew Rate
AO
Guaranteed by Design
Guaranteed by Design
Guaranteed by Design
Guaranteed by Design
55
3
70
10
6
dB
GBW
SR
MHz
V/us
mS
Trans-conductance
gm
0.2
0.7
PWM Controller Gate Drivers
Lower Gate Sourcing Current
Lower Gate Sinking Current
Lower Gate RDS(ON) Sinking
PHASE Falling to LGATE Rising
Delay
ILG_SRC
ILG_SNK
RLG_SNK
VCC – VLGATE = 6V
-1
1.5
2
A
A
Ω
VLGATE = 6V
VLGATE = 0.1V
4
VCC = 12V; VPHASE < 1.2V to VLGATE
1.2V
>
>
30
30
90
ns
ns
LGATE Falling to PHASE Rising
Delay
VCC = 12V; VLGATE < 1.2V to VPHASE
1.2V
90
18
High-Side MOSFET
RDS(ON)
VFB
Switch ON Resistance
Reference Voltage
VCC = 12V
mΩ
V
Nominal Feedback Voltage
Enable Voltage
0.591 0.6 0.609
0.3 0.35
EN Enable Threshold
Protection section
VEN
V
FB Under Voltage Protection
FB Over Voltage Protection
VCC Over Voltage Protection
Over Current Threshold
Soft-Start Interval
VFB_UVP FB falling
55
115 130 145
16 17 18
-425 -375 -325
2.4 3.6 5.4
150 165
65
75
%
%
VFB_OVP FB rising
VCC_OVP
VOCP
TSS
V
mV
ms
℃
Temperature Shutdown
TSD
Guaranteed by Design
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.
θJA is measured in the natural convection at TA = 25°C on a low effective thermal conductivity test board of
JEDEC 51-3 thermal measurement standard.
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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EM5812/A
Typical Operating Characteristics
Power On Waveform
Turn On from EN
VIN
VEN
VOUT
VOUT
LGATE
ILx
LGATE
ILx
VIN=12V,VOUT=1.5V,COUT=1000uF,No Load. VIN=12V,VOUT=1.5V,COUT=1000uF,No Load.
Turn Off from EN
Load Transient Response (Turn on)
IOUT
VEN
VOUT
VOUT
PHASE
LGATE
ILx
VIN=12V,VOUT=1.5V,COUT=1000uF,IOUT=8A. VIN=12V,VOUT=1.5V,COUT=1000uF,Load=0~9A
Load Transient Response (Turn off)
Over Current Protection
PHASE
VOUT
IOUT
VOUT
PHASE
IOUT
VIN=12V,VOUT=1.5V,COUT=1000uF,
Load=0~9A
VIN=12V, VOUT=1.5, COUT=1000uF.
Output Short Ground
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EM5812/A
Over Current Protection
PHASE
VOUT
IOUT
VIN=12V, VOUT=1.5, COUT=1000uF.
Turn On to Short Circuit
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EM5812/A
Functional Description
EM5812/A is a voltage mode synchronous buck
PWM controller. The compensation circuit is
implemented internally to minimize the external
component count. This device provides complete
protection function such as over current protection,
under voltage protection and over voltage
protection.
UVP, Under Voltage Protection
The FB voltage is monitored for under voltage
protection. The UVP threshold is typical 0.4V.
When UVP is triggered, EM5812/A will shut down
the converter and cycles the soft start function in a
hiccup mode.
Supply Voltage
OVP, Over Voltage Protection
The VCC pin provides the bias supply of EM5812/A
control circuit, as well as lower MOSFET’s gate and
the BOOT voltage for the upper MOSFET’s gate. A
minimum 0.1uF ceramic capacitor is recommended
to bypass the supply voltage.
The FB voltage is monitored for over voltage
protection. The OVP threshold is typical 0.8V.
When OVP is triggered, EM5812/A will turn off
upper MOSFET and turn on lower MOSFET.
Power ON Reset
Output Inductor Selection
To let EM5812/A start to operation, VCC voltage
must be higher than its POR voltage even when EN
voltage is pulled higher than enable high voltage.
Typical POR voltage is 4.2V.
The output inductor is selected to meet the output
voltage ripple requirements and minimize the
response time to the load transient. The inductor
value determines the current ripple and voltage
ripple. The ripple current is approximately the
following equation:
Enable
To let EM5812/A start to operation, EN voltage
must be higher than its enable voltage. Typical
enable voltage is 0.3V.
V − VOUT
VOUT
IN
ΔIL =
∗
L
V *F
IN
SW
Soft Start
EM5812/A provides soft start function internally.
The FB voltage will track the internal soft start
signal, which ramps up from zero during soft start
period.
Output Capacitor Selection
An output capacitor is required to filter the output
and supply the load transient. The selection of
output capacitor depends on the output ripple
voltage. The output ripple voltage is approximately
bounded by the following equation:
OCP, Over Current Protection
The over current function protects the converter
from a shorted output by using lower MOSFET’s
on-resistance to monitor the current. The OCP level
can be calculated as the following equation:
1
ΔVOUT = ΔIL *(ESR +
)
8*F * COUT
SW
VOCP
IOCP = −
RDS(ON)
When OCP is triggered, EM5812/A will shut down
the converter and cycles the soft start function in a
hiccup mode. If over current condition still exist
after 3 times of hiccup, EM5812/A will shut down
the controller and latch.
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EM5812/A
Input Capacitor Selection
Power MOSFET Selection
Use a mix of input bypass capacitors to control the
voltage overshoot across the MOSFET. Use small
ceramic capacitors for high frequency decoupling
and bulk capacitors to supply the current needed
each time the upper MOSFET turn on. Place the
small ceramic capacitors physically close to the
MOSFETs and between the drain of the upper
MOSFET and the source of the lower MOSFET. The
important parameters of the input capacitor are
the voltage rating and the RMS current rating.
The capacitor voltage rating should be at least 1.25
times greater than the maximum input voltage and
a voltage rating of 1.5 times is a conservative
guideline. The RMS current rating requirement can
be expressed as the following equation:
The EM5812/A requires a low-side N-Channel
power MOSFETs. These should be selected based
upon on-resistance, breakdown voltage, gate
supply requirement, and thermal management
requirements.
In high current applications, the MOSFET power
dissipation, package selection and heat sink are the
dominate design factor. The power dissipation
includes two loss components: conduction loss and
switching loss. The conduction losses are the
largest component of power dissipation for both
the upper and lower MOSFETs. These losses are
distributed between the two MOSFETs according
to duty factor.
The power dissipations in the two MOSFETs are
approximately the following equation:
IRMS = IOUT D(1 -D)
PDUPPER = I2OUT *RDS(ON) *D + 0.5*IOUT *V *F *tSW
IN
SW
For a through hole design, several electrolytic
capacitors may be needed. For surface mount
designs, solid tantalum capacitors can also be used
but caution must be exercised with regard to the
capacitor surge current rating. These capacitors
must be capable of handling the surge current at
power-up. Some capacitor series available from
reputable manufacturers are surge current tested.
PDLOWER = I2OUT *RDS(ON) *(1 - D)
Where D is the duty cycle, tSW is the combined
switch ON and OFF time.
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EM5812/A
Ordering & Marking Information
Device Name: EM5812GE for SOP-8 EP
EM
5812
ABCDEFG
EM5812GE Device Name
ABCDEFG: Date Code
Device Name: EM5812AGE for SOP-8 EP
EM
5812A
EM5812AGE Device Name
ABCDEFG: Date Code
ABCDEFG
Outline Drawing
SOP-8 EP
J
F
I
I
K
G
H
D
E
M
N
B
C
A
Dimension in mm
Dimension
Min.
A
B
C
D
E
F
G
H
I
J
K
M
N
4.70 3.70
5.80
0.33
1.20 0.08 0.40 0.19 0.25
3.2
2.21
0∘
Typ.
1.27
Max.
5.10 4.10
6.20
0.51
1.62 0.28 0.83 0.26 0.50
3.6
2.61
8∘
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