KINGBOR KB3302

Kingbor Technology Co.,Ltd
KB3302
TEL:(86)0755-26508846 FAX:(86)0755-26509052
2Amp, 2MHz Step-up Switching
regulator with Soft-Start
DESCRIPTION
FEATURES
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Up to 95% Efficiency
TDB uA No Load Current
1000mA Output Current
1.5V to 16V Input Voltage Range
Programmable switching frequency up to 2MHz
Output voltage up to 32V
Constant switching frequency current-mode control
1.23V Reference Allows Low Output Voltages
Shutdown Mode Draws ) 10 µA Supply Current
Low saturation voltage switch: 220mV at 2A
Overtemperature Protected,Soft-Start function
8-Pin MSOP Packages
The KB3302 is a high-frequency current-mode step-up
switching regulator with an integrated 2A power transistor. Its high switching frequency (programmable up to
2MHz) allows the use of tiny surface-mount external passive components. Programmable soft-start eliminates high
inrush current during start-up. The internal switch is rated
at 32V making the converter suitable for high voltage applications such as Boost, SEPIC and Flyback.
The operating frequency of the KB3302 can be set with an
external resistor. The ability to set the operating frequency
gives the KB3302 design flexibilities. A dedicated COMP
pin allows optimization of the loop response. The KB3302
is available in thermally enhanced 8-Pin MSOP packages.
APPLICATIONS
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Flat screen LCD bias supplies
TFT bias supplies
XDSL power supplies
Medical equipment
Digital video cameras
Portables devices
White LED power supplies
TYPICAL APPLICATION
KB3302 Efficiency
L1
3.3µH
VIN = 3.3V
TO 4.2V
VOUT
5.0V
1000mA
1N5819
C1
4.7µF
95
VOUT = 5V
90
6
5
7
SHDN
GND
100nF
KB3302
MSOP8
SS
4
R1
300k
SW
FB
COMP
2
85
C3
22 µF
1
ROSC
8
R3
10.7k
R3
17.4k
R2
100k
1nF
Efficiency (%)
VIN
3
1.2MHz
VIN = 4.2V
80
75
70
65
60
VIN = 3.6V
L1: Sumida CR43
Figure 1. 1.2MHzAll Ceramic Capacitor Single Li-ion Cell
to 5V Boost Converter.
VIN = 2.6V
55
50
0.001
0.010
0.100
1.000
Load Current (A)
1
Kingbor Technology Co.,Ltd
KB3302
TEL:(86)0755-26508846 FAX:(86)0755-26509052
ABSOLUTE MAXIMUM RATINGS (Note 1)
Input Supply Voltage .................................. – 0.3V to 18V
SHDN, V FB Voltages .................................. – 0.3V to 5V
SW Voltage ................................................ – 0.3V to 32V
PACkAGE/ORDER INFORMATION
TOP VIEW
10 SS
COMP 1
FB 2
SHDN 3
9 ROSC
GND
8 VIN
GND
4
7 SW
GND
5
6 SW
DD PACKAGE
10-LEAD (3mm × 3mm) PLASTIC DFN
Peak SW Sink and Source Current ........................ 2A
Operating Temperature Range (Note 2) .. – 40°C to 85°C
Junction Temperature (Note 3) ............................ 125°C
Storage Temperature Range ................ – 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
ORDER PART
NUMBER
ORDER PART
NUMBER
TOP VIEW
COMP 1
KB3302DD
8 SS
KB3302EMS
7 ROSC
FB 2
GND
SHDN 3
6 VIN
GND 4
5 SW
3000 Units on Tape and Reel
DD PART MARKING
2500 Units on Tape and Reel
EMS PART MARKING
8-LEAD PLASTIC MSOP
EXPOSED PAD IS PGND
MUST BE CONNECTED TO GND
EXPOSED PAD IS PGND (PIN 11)
MUST BE CONNECTED TO GND
TJMAX = 125°C, θJA = 45°C/W, θJC = 10°C/W
TJMAX = 125°C, θJA = 45°C/W, θJC = 10°C/W
ELECTRICAL CHARACTERISTICS
Unless specified: VIN = 2V, SHDN = 1.5V, ROSC = 7.68kΩ, -40°C < T A = TJ < 85°C
Parameter
Test Conditions
Min
Undervoltage Lockout Threshold
Typ
Max
Unit
1.3
1.4
V
16
V
1.260
V
1.267
V
Maximum Operating Voltage
Feedback Voltage
Feedback Voltage Line
Regulation
FB Pin Bias Current
TA = 25°C
1.224
-40°C < TA < 85°C
1.217
1.5V < VIN < 16V
1.242
0.01
40
%
80
nA
Error Amplifier Transconductance
60
µΩ−1
Error Amplifier Open-Loop Gain
49
dB
COMP Source Current
VFB = 1.1V
5
µA
COMP Sink Current
VFB = 1.4V
5
µA
VSHDN = 1.5V, VCOMP = 0 ( Not Switching )
1.1
1.6
mA
VSHDN = 0
10
18
µA
1.7
MHz
VIN Quiescent Supply Current
VIN Supply Current in Shutdown
Switching Frequency
1.3
1.5
Maximum Duty Cycle
85
90
Minimum Duty Cycle
0
Switch Current Limit
Switch Saturation Voltage
2
%
2
ISW = 2A
2.8
220
%
A
350
mV
Kingbor Technology Co.,Ltd
KB3302
TEL:(86)0755-26508846 FAX:(86)0755-26509052
ELECTRICAL CHARACTERISTICS
Unless specified: VIN = 2V, SHDN = 1.5V, ROSC = 7.68kΩ, -40°C < T A = TJ < 85°C
Parameter
Test Conditions
Switch Leakage Current
Min
VSW = 5V
Shutdown Threshold Voltage
1.02
Typ
Max
Unit
0.01
1
µA
1.1
1.18
V
µA
VSHDN = 1.2V
-4.6
VSHDN = 0
0
VSS = 0.3V
1.5
µA
Thermal Shutdown Temperature
160
°C
Thermal Shutdown Hysteresis
10
°C
Shutdown Pin Current
Soft-Start Charging Current
µA
0.1
TYPICAL PERFORMANCE CHARACTERISTICS
VIN Current vs SHDN Pin Voltage
1.2
-3
0.1
VIN = 2V
VIN = 2V
1
V SHDN = 1.25V
0.08
0.6
0.4
125ºC
-40ºC
0.2
25ºC
Current (µA)
125ºC
0.8
V IN Current (mA)
VIN Current (mA)
Shutdown Pin Current
vs Temperature
VIN Current vs SHDN Pin Voltage
0.06
0.04
-4
VIN = 2V
-5
VIN = 12V
0.02
-40ºC
0
0
0
0.5
1
-6
0
1.5
0.2
0.4
0.6
0.8
1.2
SHDN Voltage (V)
SHDN Voltage (V)
Soft-Start Charging Current
vs Temperature
-50
-25
0
25
50
75
100
125
Temperature (ºC)
Transconductance vs Temperature
80
2
VIN = 2V
Transconductance (µΩ )
V SS = 0.3V
-1
1.8
Current (µA)
1
1.6
1.4
1.2
70
60
50
40
30
1
-50
-25
0
25
50
75
Temperature (ºC)
100
125
-50
-25
0
25
50
75
100
125
Temperature (ºC)
3
Kingbor Technology Co.,Ltd
KB3302
TEL:(86)0755-26508846 FAX:(86)0755-26509052
TYPICAL PERFORMANCE CHARACTERISTICS
Feedback Voltage vs Temperature
Switching Frequency
vs Temperature
ROSC vs Switching Frequency
1.7
100
1.3
25ºC
10
1.2
VIN = 12V
1.5
VIN = 2V
1.4
1.15
1
-50
-25
0
25
50
75
100
1.3
125
0.0
0.5
1.0
Temperature (ºC)
2.0
2.5
3.0
-50
85ºC
200
-40ºC
1.5
2.8
1.4
2.6
2.4
100
2.2
0.5
1
1.5
2
2.5
-25
0
75
125
1.2
25
50
75
100
-50
-25
0
25
50
75
100
125
Temperature (ºC)
VIN Current in Shutdown
vs Input Voltage
VIN Quiescent Current vs Temperature
Shutdown Threshold
vs Temperature
50
1.20
Not Switching
Shutdown Threshold (V)
VIN = 2V
1.2
40
VIN = 16V
VIN Current ( µA)
VIN Current (mA)
100
1.3
Temperature (ºC)
Switch Current (A)
1.3
50
1
-50
3
25
1.1
2
0
0
Minimum VIN vs Temperature
3
Input Voltage (V)
Current Limit (A)
25ºC
0
-25
Temperature (ºC)
Switch Current Limit
vs Temperature
400
300
1.5
Frequency (MHz)
Switch Saturation Voltage
vs Switch Current
VCESAT (mV)
1.6
Frequency (MHz)
VIN = 2V
1.25
ROSC (KΩ )
Feedback Voltage (V)
ROSC = 7.68KΩ
1.1
1
VIN = 2V
0.9
-40ºC
30
125ºC
20
10
1.15
1.10
1.05
VSHDN = 0
0.8
0
-50
-25
0
25
50
75
Temperature (ºC)
4
100
125
1.00
0
5
10
Input Voltage (V)
15
20
-50
-25
0
25
50
75
Temperature (ºC)
100
125
Kingbor Technology Co.,Ltd
KB3302
TEL:(86)0755-26508846 FAX:(86)0755-26509052
PIN FUNCTIONS
Pin
Pin Name
1
COMP
2
FB
Pin Function
The output of the internal transconductance error amplifier. This pin is used for loop compensation.
The inverting input of the error amplifier. Tie to an external resistive divider to set the output voltage.
3
SHDN
Shutdown Pin. The accurate 1.1V shutdown threshold and the 4.6uA shutdown pin current
hysteresis allow the user to set the undervoltage lockout threshold and hysteresis for the switching
regulator. Pulling this pin below 0.1V causes the converter to shut down to low quiescent current.
Tie this pin to IN if the UVLO and the shutdown features are not used. This pin should not be left
floating.
4
GND
Ground. Tie to the ground plane.
5
SW
Collector of the internal power transistor. Connect to the boost inductor and the rectifying diode.
6
IN
7
ROSC
8
SS
Power Supply Pin. Bypassed with capacitors close to the pin.
A resistor from this pin to the ground sets the switching frequency.
Soft-Start Pin. A capacitor from this pin to the ground lengthens the start-up time and reduces startup current.
Exposed Pad
The exposed pad must be soldered to the ground plane on the PCB for good thermal conduction.
SIMPLIFIED BLOC DIAGRAM
IN
6
SW
5
4.6µA
SHDN
3
+
CMP
INTERNAL
SUPPLY
1.1V
2
COMP
1
ENABLE
VOLTAGE
THERMAL
REFERENCE
SHUTDOW N
1.242V
FB
CLK
+
-
REG
-
EA
PWM
REG
+
R
Q
S
1.5µA
SS
+
8
ILIM
I-LIMIT
-
REG_GOOD
R SENSE
ENABLE
Σ
+
+
ROSC
7
CLK
OSCILLATOR
SLOP E COMP
+
ISEN
4
GND
5
Kingbor Technology Co.,Ltd
KB3302
TEL:(86)0755-26508846 FAX:(86)0755-26509052
OPERATION
The KB3302 is a programmable constant-frequency peak
current-mode step-up switching regulator with an
integrated 2A power transistor. Referring to the block
diagrams in Figures 2 and 3, the power transistor is
switched on at the trailing edge of the clock. Switch
current is sensed with an integrated sense resistor. The
sensed current is summed with the slope-compensating
ramp before compared to the output of the error
amplifier EA. The PWM comparator trip point determines
the switch turn-on pulse width. The current-limit
comparator ILIM turns off the power switch when the
switch current exceeds the 2.8A current-limit threshold.
ILIM therefore provides cycle-by-cycle current limit.
Current-limit is not affected by slope compensation
because the current comparator ILIM is not in the PWM
signal path.
Current-mode switching regulators utilize a dual-loop
feedback control system. In the KB3302 the amplifier
output COMP controls the peak inductor current. This is
the inner current loop. The double reactive poles of the
output LC filter are reduced to a single real pole by the
inner current loop, easing loop compensation. Fast
transient response can be obtained with a simple Type-2
compensation network. In the outer loop, the error
amplifier regulates the output voltage.
APPLICATIONS INFORMATION
Setting the Output Voltage
An external resistive divider R1 and R2 with its center tap
tied to the FB pin (Figure 4) sets the output voltage.
V
R1 = R2 ⎛⎜ OUT − 1 ⎞⎟
1
.
⎝ 242V
⎠
(1)
VOUT
KB3302
R1
40nA
2
FB
R2
Figure 4. The Output Voltage is set with a Resistive Divider
The input bias current of the error amplifier will introduce
an error of:
∆VOUT 40nA (R1 // R2 )100
=
%
VOUT
1.242V
(2)
The percentage error of a VOUT = 5V converter with R1 =
The switching frequency of the KB3302 can be programmed 100KΩ and R2 = 301KΩ is
up to 2MHz with an external resistor from the ROSC pin
to the ground. For converters requiring extreme duty
∆VOUT 40nA (100K // 301K )100
=
= 0.24%
cycles, the operating frequency can be lowered to
1.242V
VOUT
maintain the necessary minimum on time or the minimum
off time.
Operating Frequency and Efficiency
The KB3302 requires a minimum input of 1.4V to operate.
A voltage higher than 1.1V at the shutdown pin enables Switching frequency of KB3302 is set with an external
the internal linear regulator REG in the KB3302. After VREG resistor from the ROSC pin to the ground. A graph showing
becomes valid, the soft-start capacitor is charged with a the relationship between ROSC and switching frequency is
1.5µA current source. A PNP transistor clamps the output given in the “Typical Characteristics”.
of the error amplifier as the soft-start capacitor voltage
rises. Since the COMP voltage controls the peak inductor High frequency operation reduces the size of passive
current, the inductor current is ramped gradually during components but switching losses are higher. The efficiencies
soft-start, preventing high input start-up current. Under of 5V to 12V converters operating at 700KHz, 1.35MHz
fault conditions (VIN<1.4V or over temperature) or when and 2MHz are shown in Figure 1(b). The peak efficiency
the shutdown pin is pulled below 1.1V, the soft-start of the KB3302 appears to decrease 0.5% for every
capacitor is discharged to ground. Pulling the shutdown 100KHz increase in frequency.
pin below 0.1V reduces the total supply current to 10µA.
6
Kingbor Technology Co.,Ltd
KB3302
TEL:(86)0755-26508846 FAX:(86)0755-26509052
APPLICATIONS INFORMATION
It is worth noting that IOUTMAX is directly proportional to the
Duty Cycle
VIN
ratio V . Equation (4) over-estimates the maximum
OUT
The duty cycle D of a boost converter is:
output current at high frequencies (>1MHz) since
switching losses are neglected in its derivation.
Nevertheless it is a useful first-order approximation.
VIN
1−
VOUT + VD
D=
V
1 − CESAT
VOUT + VD
(3)
where VCESAT is the switch saturation voltage and VD is
voltage drop across the rectifying diode.
Using VCESAT = 0.3V, VD = 0.5V and ILIM = 2A in (3) and (4),
the maximum output currents for three VIN and VOUT
combinations are shown in Table 1.
Maximum Output Current
In a boost switching regulator the inductor is connected
to the input. The DC inductor current is the input current.
When the power switch is turned on, the inductor current
flows into the switch. When the power switch is off, the
inductor current flows through the rectifying diode to the
output. The output current is the average diode current.
The diode current waveform is trapezoidal with pulse width
(1 – D)T (Figure 5). The output current available from a
boost converter therefore depends on the converter
operating duty cycle. The power switch current in the
KB3302 is internally limited to 2A. This is also the maximum
inductor or the input current. By estimating the conduction
losses in both the switch and the diode, an expression of
the maximum available output current of a boost converter
can be derived:
IOUTMAX =
ILIM VIN ⎡
D VD − D(VD − VCESAT ) ⎤
1−
−
⎢
⎥
VOUT ⎣
45
VIN
⎦
(4)
where ILIM is the switch current limit.
IIN
Inductor Current
ON
OFF
ON
Switch Current
Diode Current
DT
(1-D)T
OFF
ON
VIN ( V )
VOUT ( V )
D
IOUTMAX ( A )
2.5
12
0.820
0.35
3.3
5
0.423
1.14
5
12
0.615
0.76
Table 1. Calculated Maximum Output Current [ Equation (4)]
Considerations for High Frequency Operation
The operating duty cycle of a boost converter decreases as
VIN approaches VOUT. The PWM modulating ramp in a
current-mode switching regulator is the sensed current ramp
of the control switch. This current ramp is absent unless
the switch is turned on. The intersection of this ramp with
the output of the voltage feedback error amplifier
determines the switch pulse width. The propagation delay
time required to immediately turn off the switch after it
is turned on is the minimum switch on time. Regulator
closed-loop measurement shows that the KB3302 has
a minimum on time of about 150ns at room temperature.
The power switch in the KB3302 is either not turned on
at all or for at least 150ns. If the required switch on time
is shorter than the minimum on time, the regulator will
either skip cycles or it will start to jitter.
Example: Determine the maximum operating frequency
of a Li-ion cell to 5V converter using the KB3302.
Assuming that VD=0.5V, VCESAT=0.3V and VIN=2.6 - 4.2V,
the minimum duty ratio can be found using (3).
IOUT
ON
OFF
DMIN
Figure 5. Current Waveforms in a Boost Regulator
4.2
5 + 0.5 = 0.25
=
0.3
1−
5 + 0 .5
1−
ON
7
Kingbor Technology Co.,Ltd
KB3302
TEL:(86)0755-26508846 FAX:(86)0755-26509052
APPLICATIONS INFORMATION
The absolute maximum operating frequency of the
DMIN
0.25
=
= 1.67MHz . The
150ns 150ns
actual operating frequency needs to be lower to allow for
modulating headroom.
converter is therefore
D(VIN − VCESAT )
(5)
fL
where f is the switching frequency and L is the inductance.
∆IL =
Substituting (3) into (5) and neglecting VCESAT ,
V ⎛
VIN ⎞
⎟
∆IL = IN ⎜⎜ 1 −
(6)
The power transistor in the KB3302 is turned off every
fL ⎝
VOUT + VD ⎟⎠
switching period for an interval determined by the
discharge time of the oscillator ramp and the propagation In current-mode control, the slope of the modulating
delay of the power switch. This minimum off time limits (sensed switch current) ramp should be steep enough to
the maximum duty cycle of the regulator at a given lessen jittery tendency but not so steep that large flux swing
decreases efficiency. Inductor ripple current ∆IL between
VOUT
25-40%
of the peak inductor current limit is a good
switching frequency. A boost converter with high V ratio
In
compromise. Inductors so chosen are optimized in size
requires long switch on time and high duty cycle. If the and DCR. Setting ∆IL = 0.3•(2) = 0.6A, VD=0.5V in (6),
required duty cycle is higher than the attainable maximum,
⎞
⎞
V ⎛
VIN
V ⎛
VIN
then the converter will operate in dropout. (Dropout is a
⎟
⎟⎟ = IN ⎜ 1 −
L = IN ⎜⎜ 1 −
(7)
f∆IL ⎝
VOUT + VD ⎠ 0.6 f ⎜⎝
VOUT + 0.5 ⎟⎠
condition in which the regulator cannot attain its set
output voltage below current limit.)
where L is in µH and f is in MHz.
The minimum off times of closed-loop boost converters set
to various output voltages were measured by lowering their Equation (6) shows that for a given VOUT, ∆IL is the highest
input voltages until dropout occurs. It was found that the
(VOUT + VD )
. If VIN varies over a wide range, then
minimum off time of the KB3302 ranged from 80 to 110ns when VIN =
2
at room temperature.
choose L based on the nominal input voltage.
Beware of dropout when operating at very low input voltages
(1.5-2V) and with off times approaching 110ns. Shorten
the PCB trace between the power source and the device
input pin, as line drop may be a significant percentage of
the input voltage. A regulator in dropout may appear as if
it is in current limit. The cycle-by-cycle current limit of the
KB3302 is duty-cycle and input voltage invariant and is
typically 2.8A. If the switch current limit is not at least 2A,
then the converter is likely in dropout. The switching
frequency should then be lowered to improve controllability.
Both the minimum on time and the minimum off time
reduce control range of the PWM regulator. Bench
measurement showed that reduced modulating range
started to be a problem at frequencies over 2MHz. Although
the oscillator is capable of running well above 2MHz,
controllability limits the maximum operating frequency.
Inductor Selection
The inductor ripple current ∆I L of a boost converter
operating in continuous-conduction mode is
8
The saturation current of the inductor should be 20-30%
higher than the peak current limit (2.8A). Low-cost powder
iron cores are not suitable for high-frequency switching
power supplies due to their high core losses. Inductors
with ferrite cores should be used.
Input Capacitor
The input current in a boost converter is the inductor
current, which is continuous with low RMS current ripples.
A 2.2-4.7µF ceramic input capacitor is adequate for most
applications.
Output Capacitor
Both ceramic and low ESR tantalum capacitors can be
used as output filtering capacitors. Multi-layer ceramic
capacitors, due to their extremely low ESR (<5mΩ), are
the best choice. Use ceramic capacitors with stable
temperature and voltage characteristics. One may be
tempted to use Z5U and Y5V ceramic capacitors for
output filtering because of their high capacitance and
Kingbor Technology Co.,Ltd
KB3302
TEL:(86)0755-26508846 FAX:(86)0755-26509052
APPLICATIONS INFORMATION
small sizes. However these types of capacitors have high
temperature and high voltage coefficients. For example,
the capacitance of a Z5U capacitor can drop below 60%
of its room temperature value at –25°C and 90°C. X5R
ceramic capacitors, which have stable temperature and
voltage coefficients, are the preferred type.
The diode current waveform in Figure 5 is discontinuous
with high ripple-content. In a buck converter the inductor
ripple current ∆IL determines the output ripple voltage.
The output ripple voltage of a boost regulator is however
much higher and is determined by the absolute inductor
current. Decreasing the inductor ripple current does not
appreciably reduce the output ripple voltage. The current
flowing in the output filter capacitor is the difference
between the diode current and the output current. This
capacitor current has a RMS value of:
IOUT
VOUT
−1
VIN
(8)
If a tantalum capacitor is used, then its ripple current rating
in addition to its ESR will need to be considered.
When the switch is turned on, the output capacitor supplies
the load current IOUT (Figure 5). The output ripple voltage
due to charging and discharging of the output capacitor is
therefore:
∆VOUT =
IOUTDT
COUT
(9)
For most applications, a 10-22µF ceramic capacitor is
sufficient for output filtering. It is worth noting that the
output ripple voltage due to discharging of a 10µF ceramic
capacitor (9) is higher than that due to its ESR.
Rectifying Diode
For high efficiency, Schottky barrier diodes should be used
as rectifying diodes for the KB3302. These diodes should
have a RMS current rating of at least 1A and a reverse
blocking voltage of at least a few Volts higher than the
output voltage. For switching regulators operating at low
duty cycles (i.e. low output voltage to input voltage
conversion ratios), it is beneficial to use rectifying diodes
with somewhat higher RMS current ratings (thus lower
forward voltages). This is because the diode conduction
interval is much longer than that of the transistor.
Converter efficiency will be improved if the voltage drop
across the diode is lower.
The rectifying diodes should be placed close to the SW
pins of the KB3302 to minimize ringing due to trace
inductance. Surface-mount equivalents of 1N5817,
1N5819, MBRM120 (ON Semi) and 10BQ015 (IRF) are
all suitable.
Soft-Start
Soft-start prevents a DC-DC converter from drawing
excessive current (equal to the switch current limit) from
the power source during start up. If the soft-start time is
made sufficiently long, then the output will enter regulation
without overshoot. An external capacitor from the SS pin
to the ground and an internal 1.5µA charging current
source set the soft-start time. The soft-start voltage ramp
at the SS pin clamps the error amplifier output. During
regulator start-up, COMP voltage follows the SS voltage.
The converter starts to switch when its COMP voltage
exceeds 0.7V. The peak inductor current is gradually
increased until the converter output comes into regulation.
If the shutdown pin is forced below 1.1V or if fault is
detected, then the soft-start capacitor will be discharged
to ground immediately.
The SS pin can be left open if soft-start is not required.
Shutdown
The input voltage and shutdown pin voltage must be greater
than 1.4V and 1.1V respectively to enable the KB3302.
Forcing the shutdown pin below 1.1V stops switching.
Pulling this pin below 0.1V completely shuts off the KB3302.
The total VIN current decreases to 10µA at 2V. Figure 6
shows several ways of interfacing the control logic to the
shutdown pin. Beware that the shutdown pin is a high
impedance pin. It should always be driven from a lowimpedance source or tied to a resistive divider. Floating
the shutdown pin will result in undefined voltage. In Figure
6(c) the shutdown pin is driven from a logic gate whose
VOH is higher than the supply voltage of the KB3302. The
diode clamps the maximum shutdown pin voltage to one
diode voltage above the input power supply.
9
Kingbor Technology Co.,Ltd
KB3302
TEL:(86)0755-26508846 FAX:(86)0755-26509052
APPLICATIONS INFORMATION
IN
IN
KB3302
KB3302
SHDN
SHDN
(b)
(a)
VIN
IN
IN
KB3302
1N4148
KB3302
SHDN
SHDN
(d)
(c)
Figure 6. Methods of Driving the Shutdown Pin
(a) Directly Driven from a Logic Gate
(b) Driven from an Open-drain N-channel MOSFET or an Open-Collector NPN Transistor (VOL < 0.1V)
(c) Driven from a Logic Gate with VOH > VIN
(d) Combining Shutdown with Programmed UVLO (See Section Below).
Programming Undervoltage Lockout
VH and VL are therefore:
The KB3302 has an internal VIN undervoltage lockout
(UVLO) threshold of 1.4V. The transition from idle to
switching is abrupt but there is no hysteresis. If the input
voltage ramp rate is slow and the input bypass is limited,
then sudden turn on of the power transistor will cause a
dip in the line voltage. Switching will stop if VIN falls below
the internal UVLO threshold. The resulting output voltage
rise may be non-monotonic. The 1.1V disable threshold of
the KB3302 can be used in conjunction with a resistive
voltage divider to raise the UVLO threshold and to add an
UVLO hysteresis. Figure 7 shows the scheme. Both VH and
VL (the desired upper and the lower UVLO threshold
voltages) are determined by the 1.1V threshold crossings,
10
⎛
R ⎞
VH = ⎜⎜ 1 + 3 ⎟⎟(1.1 V )
R4 ⎠
⎝
VL = VH − VHYS = VH − IHYSR3
(10)
Re-arranging,
R3 =
VHYS
IHYS
(11)
R4 =
R3
VH
−1
1 .1
(12)
Kingbor Technology Co.,Ltd
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APPLICATIONS INFORMATION
The turn off voltage is:
VL = VH − VHYS = 2.75 − 0.69 = 2.06 V > 1.4 V .
IN
Frequency Compensation
6/8
I HYS
Figure 8 shows the equivalent circuit of a boost converter
using the KB3302. The output filter capacitor and the load
form an output pole at frequency:
4.6µA
R3
SWITCH CLOSED
WHEN Y = “1”
SHDN
3
ωp2 = −
+
Y
1.1V
R4
2IOUT
2
=−
VOUTC2
ROUTC2
COMPARATOR
where C2 is the output capacitor and ROUT =
KB3302
(13)
VOUT
is the
IOUT
equivalent load resistance.
The zero formed by C2 and its equivalent series resistance
(ESR) is neglected due to low ESR of the ceramic output
capacitor.
Figure 7. Programmable Hysteretic UVLO Circuit
with VL > 1.4 V .
There is also a right half plane (RHP) zero at angular
frequency:
Example: Increase the turn on voltage of a VIN = 3.3V boost
converter from 1.4V to 2.75V.
ωZ 2 =
Using VH = 2.75V and R4 = 100KΩ in (12),
ROUT (1 − D )2
L
(14)
ωz2 decreases with increasing duty cycle D and increasing
IOUT. Using the 5V to 12V boost regulator (1.35MHz) in
Figure 1(a) as an example,
R3 = 150KΩ .
The resulting UVLO hysteresis is:
ROUT ≥
VHYS = IHYSR3 = 4.6µA • 150KΩ = 0.69V .
5V
= 6.8Ω
0.74 A
I
V
IN
OUT
POWER
STAGE
VOUT
ESR
C5
R1
R OUT
C2
COMP
Gm
-
FB
+
R3
RO
C6
C4
1.242V
R2
VOLTAGE
REFERENCE
Figure 8. Simplified Block Diagram of a Boost Converter
11
Kingbor Technology Co.,Ltd
KB3302
TEL:(86)0755-26508846 FAX:(86)0755-26509052
APPLICATIONS INFORMATION
ωp1 = −
5
12 + 0.5 = 0.62
D=
0 .3
1−
12 + 0.5
1−
= −260 rads −1 = −41Hz
C4 and R3 also forms a zero with angular frequency:
Therefore
ωp 2 ≤
1
1
=−
RO C 4
4.7MΩ • 820pF
1
1
=−
R 3C 4
30.9KΩ • 820pF
ωZ1 = −
2
= 29.4Krads−1 = 4.68KHz
(6.8Ω ) • (10µF )
= −39.5 Krads −1 = −6.3 KHz
and
ωZ 2 ≥
6.8Ω • (1 − 0.62)2
= 209 Krads −1 = 33.3KHz
4.7µH
The spacing between p2 and z2 is the closest when the
converter is delivering the maximum output current from
the lowest VIN. This represents the worst-case compensation
condition. Ignoring C5 and C6 for the moment, C4 forms a
low frequency pole with the equivalent output resistance
RO of the error amplifier:
Amplifier Open Loop Gain
49dB
RO =
=
= 4.7MΩ
Transconduc tan ce
60µΩ −1
The poles p1, p2 and the RHP zero z2 all increase phase
shift in the loop response. For stable operation, the overall
loop gain should cross 0dB with -20dB/decade slope. Due
to the presence of the RHP zero, the 0dB crossover frequency
z2
. Placing z1 near p2 nulls its
3
effect and maximizes loop bandwidth. Thus
should not be higher than
R 3C 4 ≈
VOUT C2
2IOUT (MAX )
(15)
R3 determines the mid-band loop gain of the converter.
Increasing R3 increases the mid-band gain and the crossover
GND
C3
R4
R3
C4
C6
R2
U1
C1
SHDN
R1
L1
C5
C2
D1
VOUT
VIN
Figure 9. Suggested PCB Layout for the KB3302. Notice that there is no via
directly under the device. All vias are 12mil in diameter.
12
Kingbor Technology Co.,Ltd
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TEL:(86)0755-26508846 FAX:(86)0755-26509052
APPLICATIONS INFORMATION
frequency. However it reduces the phase margin. The
values of R3 and C4 can be determined empirically by
observing the inductor current and the output voltage
during load transient. Compensation is optimized when
the largest R3 and the smallest C4without producing
ringing or excessive overshoot in its inductor current and
output voltage are found.
C5 adds a feedforward zero to the loop response. In some
cases it improves the transient speed of the converter. C6
rolls off the gain at high frequency. This helps to stabilize
the loop. C5 and C6 are often not needed.
Board Layout Considerations
In a step-up switching regulator, the output filter capacitor,
the main power switch and the rectifying diode carry
switched currents with high di/dt. For jitter-free operation,
the size of the loop formed by these components should
be minimized. Since the power switch is integrated inside
the KB3302, grounding the output filter capacitor next to
the KB3302 ground pin minimizes size of the high di/dt
current loop. The input bypass capacitors should also be
placed close to the input pins. Shortening the trace at the
SW node reduces the parasitic trace inductance. This not
only reduces EMI but also decreases the sizes of the
switching voltage spikes and glitches.
Figure 9 shows how various external components are placed
around the KB3302. The frequency-setting resistor should
be placed near the ROSC pin with a short ground trace
on the PC board. These precautions reduce switching
noise pickup at the ROSC pin.
To achieve a junction to ambient thermal resistance (θJA)
of 40°C/W, the exposed pad of the KB3302 should be
properly soldered to a large ground plane. Use only 12mil
diameter vias in the ground plane if necessary. Avoid using
larger vias under the device. Molten solder may seep
through large vias during reflow, resulting in poor adhesion,
poor thermal conductivity and low reliability.
Typical Application Circuits
D1
L1
VIN
5V
VOUT
12V, 0.7A
10BQ015
6
OFF ON 3
C1
2.2µF
R1
174K
5
IN
SHDN
FB
95
2
COMP
GND
C3
47nF
4
1
ROSC
7
C6
R4
85
R2
20K
R3
C4
All Capacitors are Ceramic.
MSOP-8 Pinout
4.7µH, 1.4MHz
90
Efficiency (%)
SS
10.5µH, 700KHz
C2
10µF
KB3302
8
Efficiency
SW
80
3.3µH, 2MHz
75
70
65
60
f / MHz
R3 / KΩ
R4 / KΩ
C4 / pF
C6 / pF
L1 / µH
0.7
22.1
22.1
2200
-
10.5 (Falco D08019)
1.35
30.9
9.31
820
-
4.7 (Falco D08017)
2
63.4
4.75
470
22
3.3 (Coilcraft DO1813P)
55
VIN = 5V
VOUT = 12V
50
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Load Current (A)
Figure 10(a). 1.35 MHz All Ceramic Capacitor 5V to 12V Boost
Converter. Pinout Shown is for MSOP-8
13
Kingbor Technology Co.,Ltd
KB3302
TEL:(86)0755-26508846 FAX:(86)0755-26509052
PACAGE DESCRIPTION
Efficiency
95
1.8µH
1-CELL
LI-ION
C1
2.2µF
IN
5V, 0.8A
85
SW
2
FB
SHDN
C2
10µF
KB3302
8
90
R1
301K
5
1
COMP
SS
GND
C3
47nF
10BQ015
VOUT
Efficiency (%)
6
OFF ON 3
VOUT = 5V
D1
L1
2.6 - 4.2V
4
7
VIN = 4.2V
80
75
70
65
R3
17.4K
ROSC
1.2MHz
R4
10.7K
R2
100K
60
VIN = 3.6V
VIN = 2.6V
55
C4
1nF
50
0.001
0.010
0.100
1.000
Load Current (A)
L1: Sumida CR43
Figure 11(a). 1.2 MHz All Ceramic Capacitor Single Li-ion Cell
to 5V Boost Converter.
4-CELL
3.6 - 6V
Figure 11(b). Efficiency of the Single Li-ion Cell to 5V Boost
Converter in Figure 11(a).
C6
L1
4.9µH
6
OFF ON 3
C1
2.2µF
2.2µF
10BQ015
C5
47pF
5
IN
VOUT
5V
D1
R1
60.4K
SW
SHDN
FB
2
C2
10µF
KB3302
8
COMP
SS
GND
C3
47nF
4
1
ROSC
7
R4
7.68K
R3
20K
L2
4.9µH
R2
20K
C4
560pF
L1 and L2: Coiltronics CTX5-1
Figure 12(a). 1.5 MHz All Ceramic Capacitor 4-Cell to 5V SEPIC Converter. Pinout Shown is for MSOP-8.
14
Kingbor Technology Co.,Ltd
KB3302
TEL:(86)0755-26508846 FAX:(86)0755-26509052
D2
D3
D4
D5
C5
0.1µF
C6
0.1µF
C7
0.1µF
L1
3.3V
D1
2.2µH
R5
150K
6
3
C1
2.2µF
5
SW
FB
2
COMP
SS
R6
100K
R2
49.9K
R3
40.2K
7
4
C2
10µF
C9
0.1µF
1
ROSC
GND
C3
47nF
8V (0.55A)
R1
274K
KB3302
8
23V (10mA)
C8
1µF
OUT1
10BQ015
IN
SHDN
OUT2
R4
7.68K
C4
820pF
D7
L1 : Cooper-Bussmann SD25-2R2
D2 - D7 : BAT54S
OUT3
-8V (10mA)
C10
1µF
D6
Figure 13(a). 1.5MHz Triple-Output TFT Power Supply.
- 3.4V to 3.8V +
0.7A (FLASH)
0.2A (TORCH)
D2
R6
0.1Ω
L1
2.2µH
SUMIDA
CR43
D1
+-
10BQ015
+
2.6 - 4.2V
LXCL-PWF1
R1
698
1/2
LM358
1-CELL
LI-ION
C1
2.2µF
6
OFF ON
3
Q1
MMBT3904T
5
IN
SW
FB
SHDN
2
KB3302
8
SS
COMP
GND
C3
10nF
4
C5
0.1µF
1
ROSC
7
R4
8.06K
C4
10nF
R5
10K
R6
17.4K
C2
4.7µF
R2
43.2K
M1
MMBF2201NT1
TORCH FLASH
Figure 14(a). 1.4MHz LuxeonTM Flash White LED Driver for Camera Phones
15
Kingbor Technology Co.,Ltd
KB3302
TEL:(86)0755-26508846 FAX:(86)0755-26509052
PACAGE DESCRIPTION - MSOP8
e/2
A
DIM
D
N
A
A1
A2
b
c
D
E1
E
e
F
L
L1
N
01
aaa
bbb
ccc
2X E/2
E1
E
PIN 1
INDICATOR
ccc C
2X N/2 TIPS
12
e
B
D
aaa C
A2 A
SEATING
PLANE
DIMENSIONS
INCHES
MILLIMETERS
MIN NOM MAX MIN NOM MAX
.043
.006
.000
.037
.030
.009
.015
.009
.003
.114 .118 .122
.114 .118 .122
.193 BSC
.026 BSC
.068 .076 .080
.016 .024 .032
(.037)
8
0°
8°
.004
.005
.010
A1
bxN
C
1.10
0.00
0.15
0.75
0.95
0.22
0.38
0.08
0.23
2.90 3.00 3.10
2.90 3.00 3.10
4.90 BSC
0.65 BSC
1.73 1.93 2.03
0.40 0.60 0.80
(0.95)
8
8°
0°
0.10
0.13
0.25
H
bbb
C A-B D
c
GAGE
PLANE
F
EXPOSED PAD
L
0.25
01
(L1)
F
DETAIL
A
BOTTOM VIEW
SIDE VIEW
SEE DETAIL
A
NOTES:
1.
CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES).
2. DATUMS -A- AND -B-
TO BE DETERMINED AT DATUM PLANE-H-
3. DIMENSIONS "E1" AND "D" DO NOT INCLUDE MOLD FLASH, PROTRUSIONS
OR GATE BURRS.
4. REFERENCE JEDEC STD MO-187, VARIATION AA-T.
Land Pattern - MSOP-8L-EDP
F
DIM
(C) G
F
P
Z
C
F
G
P
X
Y
Z
DIMENSIONS
INCHES
MILLIMETERS
(.161)
.081
.098
.026
.016
.063
.224
(4.10)
2.08
2.50
0.65
0.40
1.60
5.70
X
NOTES:
1.
THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY.
CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR
COMPANY'S MANUFACTURING GUIDELINES ARE MET.
16
Kingbor Technology Co.,Ltd
KB3511
TEL:(86)0755-26508846 FAX:(86)0755-26509052
PACAGE DESCRIPTION - DFN33
A
E
B
DIM
A
A1
A2
b
C
D
E
e
L
N
aaa
bbb
E
PIN 1
INDICATOR
(LASER MARK)
DIMENSIONS
INCHES
MILLIMETERS
MIN NOM MAX MIN NOM MAX
.031
.039
.000
.002
(.008)
.007 .009 .011
.074 .079 .083
.042 .048 .052
.114 .118 .122
.020 BSC
.012 .016 .020
10
.003
.004
0.80
1.00
0.00
0.05
(0.20)
0.18 0.23 0.30
1.87 2.02 2.12
1.06 1.21 1.31
2.90 3.00 3.10
0.50 BSC
0.30 0.40 0.50
10
0.08
0.10
A
SEATING
PLANE
aaa C
A1
1
C
A2
C
2
LxN
D
N
bxN
bbb
e
C A B
NOTES:
1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES).
2. COPLANARITY APPLIES TO THE EXPOSED PAD AS WELL AS TERMINALS.
Land Pattern - DFN33-10
K
DIM
(C)
H
G
Y
X
Z
C
G
H
K
P
X
Y
Z
DIMENSIONS
INCHES
MILLIMETERS
(.112)
.075
.055
.087
.020
.012
.037
.150
(2.85)
1.90
1.40
2.20
0.50
0.30
0.95
3.80
P
NOTES:
1.
THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY.
CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR
COMPANY'S MANUFACTURING GUIDELINES ARE MET.
Kingbor Technology
TEL:(86)0755-26508846 FAX:(86)0755-26509052 www.kingbor.com
17