ADDtek AMC3202 1.5a 280khz boost regulator Datasheet

AMC3202
1.5A 280kHz BOOST REGULATORS
www.addmtek.com
DESCRIPTION
FEATURES
The AMC3202 is a 280kHz switching regulator with a
high efficiency, 1.5A integrated switch. The part operates over
a wide input voltage range, from 2.7V to 30V. The AMC3202
utilizes current mode architecture, which allows excellent load
and line regulation, as well as a practical means for limiting
current. Combining high frequency operation with a highly
integrated regulator circuit results in an extremely compact
power supply solution.
Build-in thermal protection to prevent the chip over heat
damage.
„
„
„
„
„
„
Integrated Power Switch: 1.5A Guaranteed.
Wide Input Range: 2.7V to 30V.
43V Build-in Power Switch Input Voltage.
High Frequency Allows for Small
Components.
Minimum External Components.
Built in Over Current Protection.
TYPICAL APPLICATION CIRCUIT
2.7 ~ 30VDC
L
APPLICATIONS
DF
VOUT
VIN
CIN
„
TFT-LCD Power Management
LED Backlight
COUT
VCC
EN
Enable
„
VSW
AMC3202
DSS
R2
PACKAGE PIN OUT
FB
SS
COMP
CSS
CP2
AGND
PGND
R1
CP1
RP
COMP
1
8
VSW
FB
2
7
PGND
SS
3
6
AGND
EN
4
5
VCC
SO-8
(Top View)
ORDER INFORMATION
SO
DM
8 pin
AMC3202DMF (Lead Free)
Note:
All surface-mount packages are available in Tape & Reel. Append the letter “T” to part number (i.e. AMC3202DMFT). The letter ”F” is
marked for Lead Free process.
Copyright © 2006 ADDtek Corp.
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AMC3202
ABSOLUTE MAXIMUM RATINGS
(Note)
30V
43V
150°C
-65°C to 150°C
260°C
Input Voltage, VCC
Switch Input Voltage, VSW
Maximum Operating Junction Temperature, TJ
Storage Temperature Range
Lead Temperature (Soldering, 10 seconds)
Note:
Exceeding these ratings could cause damage to the device. All voltages are with respect to Ground.
Currents are positive into, negative out of the specified terminal.
BLOCK DIAGRAM
VCC
5
Shutdown
Thermal
Shutdown
2.0V
Regulator
8 VSW
Delay
Timer
EN
S
Oscillator
Sync
4
PWM
Latch
Q
Switch
Driver
R
0.4V Detector
Frequency Shift
5:1
4uA
SS
3
FB
2
X5
-
1.276V
AGND
63mΩ
+
+
-
Error
Amp
PWM
Comparator
Slope
Compensation
∑
6
7
Ramp
Summer
PGND
1
COMP
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AMC3202
PIN DESCRIPTION
Pin
Number
Pin Name
1
COMP
Loop compensation pin. This pin is the output of the error amplifier and is used for loop
compensation. Loop compensation can be implemented by a simple RC network.
2
FB
Feedback pin. Sense the output voltage and referenced to 1.276V. When the voltage at this
pin falls below 0.4V, chip switching-frequency reduces to a much lower frequency.
3
SS
Soft Start pin. Left this pin floating if soft start function is not used.
4
EN
Enable pin. A TTL low will shut down the chip and high enable the chip. This pin may
also be used to synchronize the part to nearly twice the base frequency. If synchronization
is not used, this pin should be either tied high or left floating for normal operation.
5
VCC
Input power supply pin. Supply power to the IC and should have a bypass capacitor
connected to AGND.
6
AGND
Analog ground. Provide a clean ground for the controller circuitry and should not be in
the path of large currents. This pin is connected to the IC substrate.
7
PGND
Power ground. This pin is the ground connection for the emitter of the power switching
transistor. Connection to a good ground plane is essential.
8
VSW
High current switch pin. Connect to the collector of the internal power switch. The open
voltage across the power switch can be as high as 40V. To minimize radiation, use a trace
as short as practical.
Exposed
Pad
Heat Pad
(PGND)
Pin Function
Heat pad. Connect to power ground. Must be soldered to electrical ground on PCB.
THERMAL DATA
Thermal Resistance from Junction to Ambient, θ JA
165°C /W
Junction Temperature Calculation: TJ = TA + (PD × θ JA).
The θJA numbers are guidelines for the thermal performance of the device/pc-board system.
Connect the ground pin to ground using a large pad or ground plane for better heat dissipation.
All of the above assume no ambient airflow.
Maximum Power Calculation:
PD(MAX)=
TJ(MAX) – TA(MAX)
θJA
TJ (°C):
Maximum recommended junction temperature
TA (°C):
Ambient temperature of the application
θJA (° C /W):
O
Junction-to-Ambient thermal resistance of the package, and other heat dissipating materials.
The maximum power dissipation for a single-output regulator is:
PD(MAX) = [(VIN(MAX) - VOUT(NOM))] × IOUT(NOM) + VIN(MAX) × IQ
Where: VOUT(NOM) = the nominal output voltage
IOUT(NOM) = the nominal output current, and
IQ = the quiescent current the regulator consumes at IOUT(MAX)
VIN(MAX) = the maximum input voltage
Then θJA = (+150 OC – TA)/PD
Copyright © 2006 ADDtek Corp.
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AMC3202
RECOMMENDED OPERATING CONDITIONS
Parameter
Symbol
Min
Supply Voltage
VIN
2.7
Average Supply Current
Output Voltage
Typ
Max
Unit
30
V
IIN
1.3
A
VOUT
42
V
TA
85°C
°C
Operating Free-air Temperature Range
DC ELECTRICAL CHARACTERISTICS
VCC = 3.3V, TA = 25°C, (Unless otherwise noted)
Parameter
FB Reference Voltage
Conditions
COMP tied to FB; Measure at FB;
2.7V≦VCC≦30V
Min
Typ
Max
Unit
1.246
1.276
1.300
V
-1.0
0.1
1.0
uA
-
0.01
0.03
%/V
FB Input Current
FB=VREF
FB Reference Voltage Line
Regulation
COMP=FB, 2.7V≦VCC≦30V
Error Amp Transconductance
ICOMP=±25uA (Note)
300
550
800
uMh
o
Error Amp Gain
(Note)
200
500
-
V/V
COMP Source Current
FB=1.0V, COMP=1.25V
25
50
90
uA
COMP Sink Current
FB=1.5V, COMP=1.25V
200
625
1500
uA
COMP High Clamp Voltage
FB=1.0V, COMP sources 25uA
1.5
1.7
1.9
V
COMP Low Clamp Voltage
FB=1.5V, COMP sinks 25uA
0.25
0.50
0.65
V
COMP Threshold
Reduce COMP from 1.5V until switching
stops
0.75
1.05
1.30
V
Base Operating Frequency
FB=1V
230
280
310
kHz
Reduced Operating Frequency
FB=0V
30
52
120
kHz
Maximum Duty Cycle
FB=1V
90
94
-
%
FB Frequency Shift Threshold
Frequency drops to reduced operating
frequency
0.36
0.40
0.44
V
320
-
500
kHz
Synchronization Range
Synchronization Pulse
Transition Threshold
Rise time=20ns
2.5
-
-
V
EN Bias Current
EN=0V
EN=3.0V
-15
-
-3.0
3.0
8.0
uA
0.50
0.85
1.20
V
12
12
80
36
350
200
uS
Shutdown Threshold
Shutdown Delay
Copyright © 2006 ADDtek Corp.
2.7V≦VCC≦12V
12V≦VCC≦30V
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AMC3202
ISWITCH=1.5A
Switch Saturation Voltage
ISWITCH=1.0A, 0°C≦TJ≦85°C (Note)
ISWITCH=1.0A, -40°C≦TJ≦0°C (Note)
ISWITCH=10mA
-
0.8
0.55
0.75
0.09
1.4
0.45
V
Switch Current Limit
50% duty cycle (Note)
80% duty cycle (Note)
1.6
1.5
1.9
1.7
2.4
2.2
A
Minimum Pulse Width
COMP=1.4V, ISW = 1.0A
100
250
300
nS
Switch Leakage
VSW=43V, VCC=0V
-
2.0
10
uA
2.7V≦VCC≦12V, 10mA≦ISW≦1.0A
10
17
-
30
100
30
100
mA/A
12V≦VCC≦30V, 10mA≦ISW≦1.5A
-
ISW=0; 2.7V≦VCC≦30V
-
5.5
8.0
mA
COMP<0.8V, EN=0V, 2.7V≦VCC≦12V
COMP<0.8V, EN=0V, 12V≦VCC≦30V
-
12
-
60
100
uA
VSW switching, maximum ISW=10mA
-
2.45
2.70
V
Thermal Shutdown
150
-
-
°C
Thermal Hysteresis
-
25
-
°C
∆ICC/∆Isw
Operating Current
Shutdown Mode Current
Minimum Operation Input
Voltage
12V≦VCC≦30V, 10mA≦ISW≦1.0A
2.7V≦VCC≦12V, 10mA≦ISW≦1.5A
Note: Guaranteed by design, not 100% tested in production.
Copyright © 2006 ADDtek Corp.
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AMC3202
CHARACTERIZATION CURVES
Icc vs. VCC During Shutdowm
Switch Frequency vs. FB
25
300
VCC=3.3V
TA=25°C
Frequency(kHz)
250
20
200
Icc(uA)
15
150
10
100
VCC=2.7V~30V
5
50
TA=25°C
0
0
0.36
0.38
0.4
0. 42
0. 44
0
10
20
IEN vs. VEN
Reference Voltage vs. Temperature
1
1. 280
VCC=3.3V
0. 75
1. 276
0.5
1. 274
0. 25
I EN(uA)
Voltage(V)
1. 278
1. 272
1. 270
0
VCC=3.3V
TA=25°C
-0. 25
1. 268
-0.5
1. 266
-0. 75
1. 264
-1
-40
0
40
Temperature(°C)
80
120
0
3
6
9
VEN(V)
VCE (SAT) vs. ISW
COMP Threshold vs. Temperature
1. 2
0.7
VCC=3.3V
TA=25°C
0.6
VCC=3.3V
TA=25°C
1. 1
0.5
1
Voltage(V)
VCE (SAT) (mV)
30
VCC(V)
FB(V)
0.4
0.3
0. 9
0.2
0. 8
0.1
0. 7
0
0. 6
0
500
1000
1500
-40
Isw(mA)
Copyright © 2006 ADDtek Corp.
0
40
80
120
Temperature(°C)
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AMC3202
Shutdown Delay vs. Temperature
280
120
275
Fosc(kHz)
285
140
100
Delay(ns)
Switching FOSC vs. Temperature
160
VCC=2.7V
80
VCC=12V
VCC=30V
60
270
265
260
40
255
20
250
245
0
-40
0
40
80
-40
120
0
40
80
120
Temperature(°C)
Temperature(°C)
Minimum VCC vs. Temperature
Switch Leakage vs. Temperature
1.85
0.35
1. 825
0. 3
VCC=0V
TA=25°C
0.25
Current(mA)
VCC,MIN(V)
1. 8
1. 775
1.75
0. 2
0.15
0. 1
0.05
1. 725
0
1. 7
-40
0
40
80
-40
120
0
40
80
120
Temperature(°C)
Temperature(°C)
Max Duty Cycle vs. Temperature
99.5
VCC=30V
99.3
Duty Cycle(%)
VCC=2.7V
99.1
98.9
VCC=3.3V
VCC=12V
98.7
VCC=2.7V ~30V
TA=25°C
98.5
-40
0
40
80
120
Temperature(°C)
Copyright © 2006 ADDtek Corp.
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AMC3202
APPLICATION INFORMATION
Operation:
The AMC3202 incorporates a current mode control scheme, in which the duty cycle of the switch is directly
controlled by switch current rather than by output voltage. The output of the oscillator turns on the power switch at a
frequency of 280kHz as shown in the block diagram. The power switch is turned off by the output of the PWM
comparator.
A TTL low voltage will shut down the chip and high voltage enable the chip through EN pin. This pin may also be
used to synchronize the part to nearly twice the base oscillator frequency. In order to synchronize to a higher frequency,
a positive transition turns on the power switch before the output of the oscillator goes high, thereby resetting the
oscillator. The synchronization operation allows multiple power supplies to operate at the same frequency. If
synchronization is not used, this pin should be either tied high or left floating for normal operation.
Component Selection:
2 .7 V D C ~ 3 0 V D C
L
V IN
DF
V OUT
22uH
C IN
C OUT
10uF
VCC
EN
E n a b le
D SS
SS
COMP
C SS
22uF
VSW
R2
FB
A M C 3202
AGND
PGND
R1
C P1
C P2
200pF
0 .1 u F
RP
5K
The AMC3202 develops a 1.276V reference from the FB pin to ground. Output voltage is set by connecting the
FB pin to an output resistor divider and the maximum output voltage is determined by the VSW pin maximum voltage
minus the output diode forward voltage. Referring to typical application circuit, the output voltage is set by the below
formula (1):
R2 ⎞
⎛
V OUT = 1 .276V ⎜ 1 +
⎟
R1 ⎠
⎝
2.7V≦VOUT≦43V-VF
(1)
where, VF is the output diode DF forward voltage.
When choosing the inductor, one must consider factors such as peak current, core and ferrite material, output
voltage ripple, EMI, temperature range, physical size, and cost. Lower values are chosen to reduce physical size of the
inductor, and higher values reduce ripple voltage and core loss. In continuous conduction mode, the peak inductor
current is equal to average current plus half of the ripple current, which should not cause inductor saturation. Based on
the tolerance of the ripple current in the circuits, the following formula (2) can be referenced:
I Ripple =
V IN (VOUT − V IN )
fLV OUT
where, f = 280kHz.
(2)
In Boost circuits, the inductor becomes part of the input filter. In continuous mode, the input current waveform is
triangular and does not contain a large pulsed current. This reduces the requirements imposed on the input capacitor
selection. Capacitors in the range of 10uF to 100uF with an ESR less than 0.3Ω work well up to full 1.5A switch
current.
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AMC3202
The VIN ripple is determined by the product of the inductor current ripple and the ESR of input capacitor, and the
VOUT ripple comes from two major sources, namely ESR of output capacitor and the charging/discharging of the output
capacitor. Ceramic capacitors have the lowest ESR, but too low ESR may cause loop stability problems. Aluminum
Electrolytic capacitors exhibit the highest ESR, resulting in the poorest AC response. One option is to parallel a ceramic
capacitor with an Aluminum Electrolytic capacitor.
Frequency Compensation
The goal of frequency compensation is to achieve desirable transient response and DC regulation while ensuring
the stability of the system. A typical compensation network, as shown in the typical application circuit, provides a
frequency response of two poles and one zero. The loop frequency compensation is performed on the output of the error
amplifier (COMP pin) with a series RC network. The main pole is formed by the series capacitor and the output
impedance of the error amplifier. The series resistor creates a zero, which improves loop stability and transient response.
A second capacitor is sometimes used to reduce the switching frequency ripple on the COMP pin.
f P1 =
1
2πC P1 RO
f Z1 =
1
2πC P1 R P
f P2 =
1
2πC P 2 R P
where, RO= error amplifier output resistance;
Soft Start
Through the addition of an external circuit, a soft-start function can be added to the AMC3202. Soft-start circuitry
prevents the COMP pin from slamming high during startup, thereby inhibiting the inductor current from rising at a high
slope. Referring to the figure shown in the following, the soft-start circuitry requires a minimum number of components
and allows the soft-start circuitry to be activated any time when the EN pin is used to restart the converter.
V IN
5
EN
V EN
V CC
4
D SS
4uA
Q
3
SS
C
SS
1
C
COMP
C P1
P2
RP
Resistor RP and capacitors CP1 and CP2 form the compensation network. At turn on, the voltage at the COMP pin
starts to come up, charging capacitor CSS through internal transistor Q, clamping the voltage at the COMP pin such that
switching begins when COMP reaches the COMP threshold, typically 1.05V. Therefore, CSS slows down the startup of
the circuit by limiting the voltage on the COMP pin. The soft-start time increases with the size of CSS.
Diode DSS discharges CSS when the voltage on the EN pin is low. If the shutdown function is not used with this
part, the cathode of DSS should be connected to VIN.
Copyright © 2006 ADDtek Corp.
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AMC3202
PACKAGE
8-Pin Plastic S.O.I.C.
SYMBOLS
A
A1
A2
D
E
H
L
θ°
MIN.
0.053
0.002
0.189
0.150
0.228
0.016
0
MAX.
0.069
0.006
0.059
0.196
0.157
0.244
0.050
8
UNIT: INCH
THERMALLY ENHANCED DIMENSIONS
PAD SIZE
E1
D1
90X90E
0.081 REF
0.081 REF
95X13E
0.086 REF
0.117 REF
UNIT: INCH
NOTES:
1. JEDEC OUTLINE. N/A
2. DIMENSIONS “D” DOES NOT INCLUDE MOLD
FLASH, PROTRUSIONS OR GATE BURRS.
MOLD FLASH, PROTRUSIONS AND GATE
BURRS SHALL NOT EXCEED 15mm (.005in) PER
SIDE.
3. DIMENSIONS “E” DOES NOT INCLUDE
INTER-LEAD FLASH, OR PROTRUSIONS.
INTER-LEAD FLASH AND PROTRUSIONS
SHALL NOT EXCEED .25mm (.010in) PER SIDE.
Copyright © 2006 ADDtek Corp.
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AMC3202
IMPORTANT NOTICE
ADDtek reserves the right to make changes to its products or to discontinue any integrated circuit product or service
without notice, and advises its customers to obtain the latest version of relevant information to verify, before placing
orders, that the information being relied on is current.
A few applications using integrated circuit products may involve potential risks of death, personal injury, or severe
property or environmental damage. ADDtek integrated circuit products are not designed, intended, authorized, or
warranted to be suitable for use in life-support applications, devices or systems or other critical applications. Use of
ADDtek products in such applications is understood to be fully at the risk of the customer. In order to minimize risks
associated with the customer’s applications, the customer should provide adequate design and operating safeguards.
ADDtek assumes to no liability to customer product design or application support. ADDtek warrants the performance of
its products to the specifications applicable at the time of sale.
ADDtek Corp.
9F, No. 20, Sec. 3, Bade Rd., Taipei, Taiwan, 105
TEL: 2-25700299
FAX: 2-25700196
Copyright © 2006 ADDtek Corp.
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