EM5812.pdf 데이터시트 (총 10 페이지) - 파일 다운로드 EM5812 데이타시트 다운로드

No Preview Available !

12A 5V/12V Step-Down Converter
EM5812/A
General Description
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.
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
Features
Package
SOP-8 EP
SOP-8 EP
Frequency
200kHz
300kHz
Applications
Notebook & Netbook
Graphic Cards & MB
Low Voltage Logic Supplies
Pin Configuration
Typical Application Circuit
Operate from 5V to 12V Voltage Supply
15mInternal 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
2012/10/04
A.3
1

No Preview Available !

Pin Assignment
EM5812/A
Pin Name Pin No.
Pin Function
LGATE
VCC
FB
EN
PHASE
VIN
BOOT
GND
Lower Gate Driver Output. Connect this pin to the gate of lower MOSFET. This pin
1 is monitored by the adaptive shoot-through protection circuitry to determine when
the lower MOSFET has turn off.
Bias Supply Voltage. This pin provides the bias supply for the EM5812/A and the
2
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.
3
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.
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
5,6 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.
EP 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.
7 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.
Signal and Power Ground for the IC. All voltages levels are measured with respect
8 to this pin. Tie this pin to the ground island/plane through the lowest impedance
connection available.
2012/10/04
A.3
2

No Preview Available !

Function Block Diagram
VCC
2
Soft Start
Internal
regulator
POR
FB 3
Vref
-
- EA
+
OTP
Ramp
PWM
E4
0.3V
Oscillator
VCC
17V
Enable
65% Vref
FB
FB
130% Vref
EM5812/A
7 BOOT
EP VI
Gate
control
logic
VCC
5,6 PHASE
VOCP
1 LGATE
8 GD
2012/10/04
A.3
3

No Preview Available !

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------------------------------------------------------------------------------- -0.3V to VCC + 0.3V
<200ns------------------------------------------------------------------------- -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
2012/10/04
A.3
4

No Preview Available !

Electrical Characteristics
VCC=12V, TA=25, unless otherwise specified
Parameter
Symbol
Test Conditions
EM5812/A
Min Typ Max Units
VCC Supply Section
VCC Supply Voltage
Supply Current
Quiescent Supply Current
VCC Power on Reset Threshold
VCC Power on Reset Hysteresis
VIN Supply Section
VIN Power on Reset Threshold
Internal Oscillator
VCC
ICC
ICCQ
VCCRTH
VCCHYS
LGATE open, Switching.
No Switching.
VINTH
4.5 13.2 V
10 mA
2 mA
4 4.2 4.4 V
0.2 V
1.5 V
Free Running Frequency
Ramp Amplitude
Error Amplifier
FSW
VOSC
EM5812
EM5812A
170 200 230 KHz
255 300 345 KHz
1 Vp-p
Open Loop DC Gain
Gain-Bandwidth Product
AO
GBW
Guaranteed by Design
Guaranteed by Design
55 70
10
dB
MHz
Slew Rate
SR Guaranteed by Design
36
V/us
Trans-conductance
PWM Controller Gate Drivers
gm
Guaranteed by Design
0.2 0.7 mS
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
VLGATE = 6V
VLGATE = 0.1V
VCC = 12V; VPHASE < 1.2V to VLGATE >
1.2V
-1
1.5
24
30 90
A
A
Ω
ns
LGATE Falling to PHASE Rising
Delay
VCC = 12V; VLGATE < 1.2V to VPHASE >
1.2V
30 90 ns
High-Side MOSFET
Switch ON Resistance
Reference Voltage
RDS(ON)
VCC = 12V
18 mΩ
Nominal Feedback Voltage
Enable Voltage
VFB
0.591 0.6 0.609 V
EN Enable Threshold
Protection section
VEN
0.3 0.35 V
FB Under Voltage Protection
VFB_UVP FB falling
55 65 75 %
FB Over Voltage Protection
VFB_OVP FB rising
115 130 145 %
VCC Over Voltage Protection
VCC_OVP
16 17 18 V
Over Current Threshold
VOCP
-425 -375 -325 mV
Soft-Start Interval
Temperature Shutdown
TSS
TSD Guaranteed by Design
2.4 3.6 5.4 ms
150 165
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.
2012/10/04
A.3
5