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Voltage Regulators
AN8016NSH
Single-channel 1.8-volt step-up DC-DC converter control IC
Overview
The AN8016NSH is a single-channel PWM DC-DC converter control IC that supports low-voltage operation. This IC allows a stepped-up voltage output to be provided with a minimal number of external components. It features a low minimum operating voltage of 1.8 V, and due to being provided in a 10-pin surface mount package with a 0.5 mm lead pitch, is optimal for use in miniature high-efficiency power supplies for portable equipment.
1 10
Unit: mm
0.5
5
6
Overall height 1.7 max.
Features
0.50.2 4.30.30 6.30.30
* Wide operating supply voltage range: 1.8 V to 14 V * High-precision reference voltage circuit: 1.27 V (allowance: 3%) SSOP010-P-0225 * Supports control over a wide output frequency range: 20 kHz to 1 MHz Note) The package of this product will be changed * Provides a fixed output current with minimal supply voltto lead-free type (SSOP010-P-0225A). See the age fluctuations by using an external resistor to set the new package dimensions section later of this output current with a totem pole structure in the output datasheet. block. * Large maximum output current of 50 mA * Timer latch short-circuit protection circuit (charge current: 1.3 A typical) * Low input voltage malfunction prevention circuit (U.V.L.O.) (circuit operation start voltage: 1.6 V typical) * On/off control function (active-high, standby current: 5 A maximum) * Fixed maximum duty ratio with small sample-to-sample variations (80% 5%) * Adjustable soft start time provided by using separate DTC and S.C.P. pins. * Adopts techniques for reducing noise, increasing the light load efficiency, and suppressing the maximum base current when turning on the npn transistor used as the external switching element.
Applications
* LCD displays, digital still cameras, PDAs
0.6250.10
0.15-0.05
+0.1
0.6250.1
3.00.30
0.20.1
Publication date: October 2002
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AN8016NSH
Block Diagram
OSC 9 VCC
Active-high
5
Off FB IN-
4 10 1
On/off control
Reference voltage supply 1.27 V
Triangular wave generator
0.7 V 0.2 V VCC 8 RB
SS pin
U.V.L.O. Error amp. 1.27 V VCC 1 A
Latch
PWM 6 0.6 V 30 k Out
Low level detector comp. Low level clamp
R S 1.27 V
Q VCC Unlatch comp. 0.23 V
High level detector comp.
0.23 V
5 A
Low level clamp
7
GND
1.27 V
S.C.P. comp.
2 SS Description Error amplifier inverting input Time constant capacitor connection for short-circuit protection Soft-start time-constant capacitor connection On/off control Supply voltage Push-pull output Ground Output-current setting resistor connection pin Oscillator circuit timing resistor/capacitor connection pin Error amplifier output
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Pin Descriptions
Pin No. 1 2 3 4 5 6 7 8 9 10 Symbol IN- S.C.P. SS Off VCC Out GND RB OSC FB
2
S.C.P.
3
AN8016NSH
Absolute Maximum Ratings
Parameter Supply voltage Off pin allowable application voltage IN- pin allowable application voltage Out pin allowable application voltage Supply current Output source current Output sink current Power dissipation
*
Symbol VCC VOFF VIN- VOUT ICC ISO(OUT) ISI(OUT) PD Topr Tstg
Rating 15 15 VCC 15 -50 +50 115 -30 to +85 -55 to +150
Unit V V V V mA mA mA mW C C
Operating temperature Storage temperature
Note) 1. Do not apply external currents or voltages to any pins not specifically mentioned. For circuit currents, '+' denotes current flowing into the IC, and '-' denotes current flowing out of the IC. 2. Except for the power dissipation, operating temperature and storage temperature, all ratings are for Ta = 25C. 3. * : Ta = 85C. For the independent IC without a heat sink. Note that the relationship between IC power dissipation and the ambient temperature must follow the derating curve.
Recommended Operating Range
Parameter Supply voltage Off control pin voltage Output source current Output sink current Timing resistance Timing capacitance Oscillator frequency Short-circuit protection time constant setting capacitance Output current setting resistance RB 0 to 10k Symbol VCC VOFF ISO(OUT) ISI(OUT) RT CT fOUT CSCP Conditions 1.8 to 14 0 to 14 -40 (min.) 40 (max.) 3 to 30 100 to 10 000 20 to 1 000 1 000 (min.) Unit V V mA mA k pF kHz pF
Electrical Characteristics at VCC = 2.4 V, Ta = 25C
Parameter U.V.L.O. block Circuit operation start voltage Error amplifier block Input threshold voltage Line regulation with input fluctuation Input bias current High-level output voltage Low-level output voltage VTH VdV IB VEH VEL
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Symbol
Conditions
Min
Typ
Max
Unit
VUON
1.45
1.6
1.75
V
Voltage follower VCC = 1.8 V to 14 V
1.23 1.85
1.27 1.0 0.2 2.0
1.31 10 1.0 2.15 0.2
V mV A V V 3
AN8016NSH
Electrical Characteristics at VCC = 2.4 V, Ta = 25C (continued)
Parameter PWM comparator block Output source current Output block Oscillator frequency Maximum duty High-level output voltage Low-level output voltage Output source current Output sink current Pull-down resistor Unlatch circuit block Input threshold voltage VTHUL 0.13 0.20 0.27 V fOUT Dumax VOH VOL ISO(OUT) ISI(OUT) RO IO = -15 mA, RB = 390 IO = 10 mA, RB = 390 VO = 0.9 V, RB = 390 VO = 0.3 V, RB = 390 RT = 12 k, CT = 330 pF 170 75 1.4 -45 20 20 190 80 -32 30 210 85 0.2 -20 40 kHz % V V mA mA k ISS VSS = 0.5 V -3.5 -5 -6.5 A Symbol Conditions Min Typ Max Unit
Short-circuit protection circuit block Input threshold voltage Input standby voltage Input latch voltage Charge current On/off control block Input threshold voltage Off mode SS pin voltage Off mode S.C.P. pin voltage Whole device Average consumption current Latch mode consumption current Standby mode current * Design reference data
Note) The characteristics listed below are theoretical values based on the IC design and are not guaranteed.
VTHPC VSTBY VIN ICHG VSCP = 0.5 V
1.17 -1.65
1.27 60 40
1.37 120 120
V mV mV A
-1.3 - 0.95
VON(TH) VOFF(SS) VOFF(SCP) RB = 390 , Duty = 50% RB = 390
0.8 0.13 0.13
1.0
1.3 0.27 0.27
V V V
ICC(AV) ICC(LA) ICC(SB)
3.4 1.8
5.0 2.4 5
mA mA A
Parameter U.V.L.O. block Reset voltage Error amplifier block VTH temperature characteristics Output source current Output sink current Open-loop gain PWM comparator block SS pin voltage 4
Symbol
Conditions
Min
Typ
Max
Unit
VR Ta = -30C to +85C VFB = 0.5 V VFB = 0.5 V - 0.5
0.8 + 0.5 -40 2 80
V
VTHdT ISO(FB) ISI(FB) AV
% A mA dB
VSS
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1.22
V
AN8016NSH
Electrical Characteristics at VCC = 2.4 V, Ta = 25C (continued)
* Design reference data (continued)
Note) The characteristics listed below are theoretical values based on the IC design and are not guaranteed.
Parameter Output block RB pin voltage Oscillator frequency supply voltage characteristics Oscillator frequency temperature characteristics
Symbol
Conditions RB = 390 VCC = 1.8 V to 14 V Ta = -30C to 85C
Min
Typ
Max
Unit
VB fdV fdT
0.13 -1 -3 +1 +3
V % %
Short-circuit protection circuit block Comparator threshold voltage On/off control block On/Off pin current IOFF VOFF = 1.5 V 23 A VTHL 1.27 V
Terminal Equivalent Circuits
Pin No. 1
VCC
Equivalent Circuit
Description IN-: Error amplifier inverting input.
I/O I
1
300
1.26 V
2 0.23 V 3 k 3 k 2 3
VCC
Latch
Output cutoff To the on/off control circuit 0.23 V Low level detection comp.
1.27 V
S R
Q
S.C.P.: Connection for the capacitor that sets the timer latch short-circuit protection circuit time constant. Use a capacitor with a value of 1 000 pF or higher. The charge current ICHG is 1.3 A (typical). However, the capacitor is charged with a time constant determined by 0.23 V and a resistor of 6 k until the pin voltage reaches 0.23 V. SS: Connection pin for the capacitor that determines the PWM output soft start period. Note that the short-circuit protection circuit does not supply charge current to S.C.P. pin until this pin voltage reaches about 0.2 V. The source current ISS is 5 A (typical). However, the capacitor is charged with a time constant determined by 0.23 V and a resistor of 6 k until the pin voltage reaches 0.23 V.
O
VCC CT PWM Unlatch comp.
To the on/off control circuit
I
0.23 V 3 k 3 k 3
0.23 V
S.C.P. pin
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AN8016NSH
Terminal Equivalent Circuits (continued)
Pin No. 4
Internal circuit start/stop
Equivalent Circuit
Description Off: This pin controls the on/off for the IC. High-level input: normal operation (VOFF > 1.3 V) Low-level input: standby mode (VOFF < 0.8 V) In the standby state, the total IC current consumption is decreased to 5 mA or under. VCC: Power supply connection. Provide an operating supply voltage of 1.8 V to 14 V.
I/O I
30 k 4 60 k
5 5
6
VCC RB IO(SO) 6 30 k
Out: This is a push-pull output. The absolute maximum rating for the output current is 50 mA. A constant-current output with excellent line regulation and minimal sample-tosample variations can be acquired by connected an external resistor to the RB pin.
O
7
7
GND: IC ground. RB: Connection for the resistor that sets the output current. Use a resistor in the range 0 to 10 k. Note that the internal resistor R1 has a value of 1.0 k. Thus the pin voltage will be 0.13 V when RB is 390 . OSC: Connection for the capacitor and resistor that determines the oscillator frequency. Use a capacitor in the range 100 pF to 10 000 pF and a resistor in the range 3 k to 30 k. Use an oscillator frequency in the range 20 kHz to 1 MHz.
8
VCC
I
Out R1 8
9
VCC
Latch
O
S R 0.23 V 9
Q
6
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Terminal Equivalent Circuits (continued)
Pin No. 10 Equivalent Circuit Description FB: Error amplifier output. A source current is about -40 A and a sink current is about 2 mA. Correct the gain and the phase frequency characteristics by inserting a capacitor and a resistor between this pin and IN- pin. I/O O
VCC 40 A C 2 mA 10 PWM
Usage Notes
* Notes on IC power dissipation Since the power dissipation in this IC increases proportionally with the supply voltage, applications must be careful to operate so that the actual power dissipation does not exceed the power dissipation. Since the output current set by the application circuit flows in the IC during the period corresponding to the output on duty factor (Du, where Dumax is 0.85), the IC power dissipation P is given by the following formula. P = (VCC - VBEQ1) x IOUT x Du + VCC x ICC < PD
Application Notes
[1] PD Ta curves of SSOP010-P-0225 PD Ta
400 386 Glass epoxy printed circuit board (50 x 50 x t0.8 mm3) Rth(j-a) = 259C/W
Power dissipation PD (mW)
300 287
Independent IC without a heat sink
Rth(j-a) = 348C/W 200
154 115 100
0 0 25 50 75 85 100 125 150
Ambient temperature Ta (C)
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Application Notes (continued)
[2] Main characteristics Timing capacitance Oscillator frequency
1 000
Maximum output duty Oscillator frequency
95
RT = 3 k
90
Oscillator frequency (kHz)
RT = 3 k RT = 6.2 k
RT = 6.2 k
Maximum duty (%)
85 RT = 12 k 80 RT = 30 k 75
100
RT = 12 k RT = 30 k 10 100 1 000 10 000
70 10 100 1 000
Timing capacitance (pF)
Oscillator frequency (kHz)
Error amplifier VTH temperature characteristics
1.28
Oscillator frequency temperature characteristics
192
190
Oscillator frequency (kHz)
-30 -10
1.278
188
Voltage (V)
1.276
186
184
1.274
182
1.272
180 10 30 50 70 90
-30
-10
10
30
50
70
90
Ambient temperature Ta (C)
Ambient temperature Ta (C)
Maximum duty temperature characteristics
81
80
Maximum duty (%)
79
78
77
76
-30
-10
10
30
50
70
90
Ambient temperature Ta (C)
8
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Application Notes (continued)
[3] Timing charts (internal waveforms)
High Off pin voltage Low 2.4 V Supply voltage (VCC) Error amplifier output (FB) S.C.P. pin voltage Power on SS pin voltage Triangular wave (CT) 2.0 V 1.27 V 1.22 V 0.7 V 0.6 V 0.4 V 0.2 V High Out pin waveform Low Soft start operation Maximum duty: 80%
Figure 1. PWM comparator operating waveforms
2.0 V Short-circuit protection comparator threshold level Dead time voltage (VDT) Error amplifier output (FB) Triangular wave (CT) Out pin waveform Low 1.27 V S.C.P. pin voltage Short-circuit protection comparator output tPE 0.06 V High Low Figure 2. Short-circuit protection operating waveforms High 1.27 V
0.6 V
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Application Notes (continued)
[4] Functional descriptions 1. Reference voltage block This circuit is composed of a band gap circuit, and outputs a 1.27 V temperature compensated reference voltage. This reference voltage is stabilized when the supply voltage is 1.8 V or higher. 2. Triangular wave generator This circuit generates a triangular wave like sawtooth with a peak of 0.75 V and a trough of 0.2 V using a capacitor (for the time constant) and resistor connected to the OSC pin (pin 9). The oscillator frequency can be set to any value by selecting appropriate values for the external capacitor and resistor, CT and RT. This oscillator can provide a frequency in the range 20 kHz to 1 MHz. The triangular wave signal is provided to the inverting input of the PWM comparator internally to the IC. Use the formulas below for rough calculation of the oscillator frequency. 1 1 fOSC - 0.75 x [Hz] VOSCL CT x R T CT x RT x ln VOSCH
VOSCH 0.75 V
VOSCL 0.2 V t1 Rapid charge t2 Discharge T
Figure 1. Triangular oscillator waveform
Note, however, that the above formulas do not take the rapid charge time, overshoot, and undershoot into account. See the experimentally determined graph of the oscillator frequency vs. timing capacitance value provided in the main characteristics section. 3. Error amplifier This circuit is an npn-transistor input error amplifier that detects and amplifies the DC-DC converter output voltage, and inputs that signal to a PWM comparator. The 1.27 V internal reference voltage is applied to the noninverting input. Arbitrary gain and phase compensation can be set up by inserting a resistor and capacitor in series between the error amplifier output pin (pin 10) and the inverting input pin (pin 1). The output voltage VOUT can be set by resistor-dividing the output as shown in figure 2. R1 + R2 VOUT =1.27 x R2
VOUT R1 R2
FB 10 Error amplifier 1.27 V To the PWM comparator input
IN- 1
Figure 2. Connection method of error amplifier
4. Timer latch short-circuit protection circuit This circuit protects the external main switching element, flywheel diode, choke coil, and other components against degradation or destruction if an excessive load or a short circuit of the power supply output continues for longer than a certain fixed period. The timer latch short-circuit protection circuit detects the output of the error amplifiers. If the DC-DC converter output voltage drops and an error amplifier output level exceeds 1.27 V, this circuit outputs a low level and the timer circuit starts. This starts charging the external protection circuit delay time capacitor. If the error amplifier output does not return to the normal voltage range before that capacitor reaches 1.27 V, the latch circuit latches, the output drive transistors are turned off, and the off-period is set to 10
10
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Application Notes (continued)
[4] Function descriptions (continued) 5. Low input voltage malfunction prevention circuit (U.V.L.O.) This circuit protects the system against degradation or destruction due to incorrect control operation when the power supply voltage falls during power on or power off. The low input voltage malfunction prevention circuit detects the internal reference voltage that changes with the supply voltage level. While the supply voltage is rising, this circuit cuts off the output drive transistor until the reference voltage reaches 1.6 V. It also sets the off-period to 100%, and at the same time holds the S.C.P. pin (pin 2) and the SS pin (pin 3) at the low level. 6. PWM comparator The PWM comparator controls the on-period of the output pulse according to its input voltage. The output transistors are turned on during periods when the OSC pin (pin 9) triangular waveform is lower than the error amplifier output pin (pin 10), the SS pin (pin 3), and the IC internally fixed dead-time voltage (about 0.6 V). The maximum duty is fixed at 80% (typical). The SS pin provides a constant-current source output of 5 A (typical), and can be used to implement soft start operation in which the output pulse on period is gradually increased by connecting an external capacitor to that pin. Note that the SS pin charge operation completes when the SS pin voltage reaches 1.22 V (typical). 7. Unlatch block The unlatch circuit holds the S.C.P. fixed at the low level while the SS pin voltage reaches the soft start operation start-level (about 0.23 V) when power is first applied. This suppresses increases in the short-circuit protection detection time associated with longer startup times. 8. Output block The output circuit has a totem pole structure. A constant-current source output with good line regulation can be set up at an arbitrary voltage by connecting a current setting resistor to the RB pin. This circuit can provide an output current of up to 50 mA. The output pin has a breakdown voltage of 15 V. 9. On/off control block The IC can be turned on or off externally. When the Off pin (pin 4) voltage is set by the application of about 1.3 V or higher, the internal reference voltage is turned on, and control operation starts. If the Off pin voltage is dropped to about 0.8 V or lower, after the S.C.P. pin and SS pin external capacitors discharge, the internal reference voltage is turned off and IC control operation is stopped. This reduces IC current consumption to 5 A or under.
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Application Notes (continued)
[5] Time constant setup for the timer latch short-circuit protection circuit Figure 4 shows the structure of the timer latch short-circuit protection circuit. The short-circuit protection comparator continuously compares a 1.27 V reference voltage with the error amplifier output VFB. When the DC-DC converter output load conditions are stable, the short-circuit protection comparator holds its average value, since there are no fluctuations in the error amplifier outputs. At this time, the output transistor Q1 will be in the conducting state, and the S.C.P. pin will be held at about 60 mV. If the output load conditions change rapidly and a high-level signal (1.27 V or higher) is input to the shortcircuit protection comparator's noninverting input from the error amplifier, the short-circuit protection comparator will output a low level and the output transistor Q1 will shut off. Then, the external capacitor CS connected to the S.C.P. pin will start to charge. When the external capacitor CS is charged to about 1.27 V, the latch circuit will latch and the off-period will be set to 100% with the output held fixed at the low level. Once the latch circuit has latched, the S.C.P. pin capacitor will be discharged to about 40 mV, but the latch circuit will not reset unless either power is turned off or the power supply is restarted using on/off control. The capacitor CS is charged from 60 mV to about 230 mV with a time constant determined by a resistor of 6 k, and is charged from 230 mV to 1.26 V by a constant current of about 1.3 A. 1) 0.06 VSCP [V] 0.23 tPE1 VSCP = (0.23 - 0.06) x {1 - exp( - )} [V] 6k * CS tPE1 [s] 0.017 x CS [mF] 2) 0.23 VSCP [V] 1.26 1.27 V = 0.23 V + ICHG x tPE2 [s] 0.80 x CS [F] tPE [s] tPE1 + tPE2 0.817 x CS [F] tPE2 CS
VSCP [V] 1.27 Short-circuit detection time tPE
0.23 0.06 tPE1 tPE2 t [s]
Figure 3. S.C.P. pin charging waveform
On/off control Internal reference VCC 1 A 0.23 V 3 k FB 10 IN- 1 3 k Error amp. S.C.P. comp. 1.27 V 1.27 V Latch R S Q Output shutoff U.V.L.O.
High level detection comparator 1.27 V
Q1
S.C.P. 2 12
CS
Figure 4. Short-circuit protection circuit
At power supply startup, the output appears to be in the shorted state, the error amplifier output goes to the high level, and the IC starts to charge the S.C.P. pin capacitor. Therefore, users must select an external capacitor that allows the DC-DC converter output voltage to rise before the latch circuit in the later stage latches. In particular, care is required if the soft start function is used, since that function makes the startup time longer.
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Application Notes (continued)
[6] Setting the soft start time A soft start function, which gradually increases the width of the output pulses at power on, will be applied if a capacitor is connected to the SS pin. This can prevent rush currents and overshoot when the power supply is turned on. The capacitor CSS is charged from 60 mV to about 230 mV with a time constant determined by a resistor of 6 k, and is charged from 230 mV to 1.22 V by a constant current of about 5 A. The following formulas express the soft start time for the duty of up to 50%. 1) 0.06 VSCP [V] 0.23 VSCP = (0.23 - 0.06) x {1 - exp( - tPE1 [s] 0.017 x CS [mF] 2) 0.23 VSCP [V] 1.26 0.52 V = 0.23 V + ICHG x tPE2 [s] 0.058 x CS [F] tSS [s] tSS1 + tSS2 0.075 x CS [F] tSS2 CS tSS1 )} [V] 6k * CS
FB (V) 1.22 0.75 0.52 0.23 0.06 tSS1 tSS2 t (s) Duty: 50% OSC SS
Soft start time DC-DC converter output voltage
Figure 5. Soft start operating waveforms
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Application Notes (continued)
[7] Parallel synchronous operation of multiple ICs Multiple instances of this IC can be operated in parallel. All the ICs will operate at the same frequency if the master and slave IC OSC pins (pin 9) are connected directly. 1. Notes on S.C.P. operation during parallel operation In the circuit in figure 6, if either the IC operating in master mode or the IC in slave mode detects a short circuit, the IC that detected the short circuit will enter latched mode. The latched mode state is a state in which the output is shut off and both the RB pin and the SS pin are set to the low level. However in this mode, this IC has an added function that holds the OSC pin at the high level (about 0.8 V). When OSC pin of the IC that did not enter latched mode goes to the high level, the internally fixed deadtime voltage (about 0.6 V) will then be lower than the OSC pin voltage, and internal PWM circuit output will stop. That will cause this IC to go to the output shorted state, and then, this IC will also switch to latched mode. Therefore, applications that require parallel synchronous operation should adopt the basic circuit structure shown in figure 6. 2. Usage notes 1) If capacitors are shared as shown in figure 7 to reduce the number of external components: * The charge current will be doubled. * The short-circuit protection circuit will not operate if the S.C.P. pin capacitor is shared. In this circuit, even if the master IC detects a short circuit, the slave IC will not detect that state, so the S.C.P. pin will remain fixed at the low level state. Note that as a result, the short-circuit protection circuit will not operate and the IC will continue to operate at the maximum duty drive.
OSC
10 10 9 8 7 6 9 8 7 6
OSC
10 10 9 8 7 6 9 8 3 7 4 6 5
AN8016NSH Master
1 2 3 4 5
AN8016NSH Slave
1 2 3 4 5
AN8016NSH Master
1 2 3 4 5
AN8016NSH Slave
1 2
S.C.P.
SS
S.C.P.
SS
S.C.P. NG
SS
Figure 6. Slave operation circuit example
Figure 7. Slave operation circuit example
2)
Note that it is not possible to operate this IC (the AN8016NSH) with the two-channel AN8017SA/AN8018SA together in parallel synchronous mode.
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Application Circuit Examples
[1] Application circuit (Step-up circuit) VIN 3V SBD 47 H MA2Q738 (MA738) VOUT 5V 200 mA
330 pF 0.1 F
12 k 390
Q1 7 GND 9 OSC 6 Out 8 RB
10 F
1 k 10 FB
2SD2408
AN8016NSH
S.C.P. 2
IN- 1
SS 3
Off 4
0.033 F 0.01 F 1.5 V
VCC 5 1 F
6.8 k 20 k Note) : Former part number The figure shows a step-up circuit that converts a 3 V input to a 5 V output. The AN8016NSH output stage has a totem pole circuit configuration, and can directly drive an n-channel MOSFET while minimizes switching loss and increasing efficiency. In this case, replace the npn transistor with an n-channel MOSFET in above circuit. [2] Notes on direct n-channel MOSFET drive 1. Select an n-channel MOSFET with a low input capacitance. The AN8016NSH was designed to drive bipolar transistors, and adopts a circuit structure that can provide a constant-current (50 mA maximum) output source current. Furthermore, it has a sink current capacity of about 50 mA. This means that designs must be concerned about increased power dissipation due to increased rise and fall times. If problems occur, an inverter may be inserted as shown in figure 1 to provide amplification. 2. Use an n-channel MOSFET of a low gate threshold voltage. Since the AN8016NSH Out pin high-level output voltage is VCC - 1.0 V (minimum), a low VT MOSFET with an adequately low on-resistance must be used. Also, if a large VGS is required, one solution is to use a transformer as shown in figure 2, and apply a voltage of twice the input voltage to the IC's VCC pin.
VIN 6 Out
SBD
VOUT
Figure 1. Output bootstrap circuit SBD
VIN
VOUT
VCC 5 6 Out
SBD
VCC 2 x VIN - VD Figure 2. Gate drive voltage bootstrap technique
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Application Circuit Examples (continued)
[2] Notes on direct n-channel MOSFET drive (continued) 3. Notes on printed circuit board pattern layout Observe the following recommendations on printed circuit board pattern layout to achieve low noise and high efficiency. 1) Use extremely wide lines for the ground lines, and isolate the IC ground from the power system ground. 2) Make the lines in the high-current system as wide as possible. 3) Position the input filter capacitor C3 as close as possible to the VCC and ground pins, and assure that there are no other paths for switching noise to enter the IC. 4) Keep the length of the line between the Out pin and the switching device (either a MOSFET or other transistor) as short as possible to provide a clean switching waveform to the switching device. 5) Use a relatively long line for the low-impedance side of the output voltage detection resistor R2.
(2) VIN SBD VOUT
Q1
7 GND 9 OSC 10 FB 6 Out 8 RB
(4)
GND (1)
AN8016NSH
IN- 1
SS 3
S.C.P. 2
24 k R2
C3
VCC 5
Off 4
(3)
(5)
[3] Evaluation board
Off
VIN
SBD
VOUT +
L1
Q1 BCE
C6
C3
+
GND R6
R4 C2 C1 R1 R2 R3
C4 C5 R5
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New Package Dimensions (Unit: mm)
* SSOP010-P-0225A (Lead-free package) 3.000.20 10 6 (1.00) 4.300.20 6.300.30
0.15-0.05
+0.10
0 to 10 0.500.20 1 (0.50) 0.50 5 0.20+0.10 -0.05 1.500.20 0.100.10
Seating plane
Seating plane
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Request for your special attention and precautions in using the technical information and semiconductors described in this material
(1) An export permit needs to be obtained from the competent authorities of the Japanese Government if any of the products or technologies described in this material and controlled under the "Foreign Exchange and Foreign Trade Law" is to be exported or taken out of Japan. (2) The technical information described in this material is limited to showing representative characteristics and applied circuits examples of the products. It neither warrants non-infringement of intellectual property right or any other rights owned by our company or a third party, nor grants any license. (3) We are not liable for the infringement of rights owned by a third party arising out of the use of the product or technologies as described in this material. (4) The products described in this material are intended to be used for standard applications or general electronic equipment (such as office equipment, communications equipment, measuring instruments and household appliances). Consult our sales staff in advance for information on the following applications: * Special applications (such as for airplanes, aerospace, automobiles, traffic control equipment, combustion equipment, life support systems and safety devices) in which exceptional quality and reliability are required, or if the failure or malfunction of the products may directly jeopardize life or harm the human body. * Any applications other than the standard applications intended. (5) The products and product specifications described in this material are subject to change without notice for modification and/or improvement. At the final stage of your design, purchasing, or use of the products, therefore, ask for the most up-to-date Product Standards in advance to make sure that the latest specifications satisfy your requirements. (6) When designing your equipment, comply with the guaranteed values, in particular those of maximum rating, the range of operating power supply voltage, and heat radiation characteristics. Otherwise, we will not be liable for any defect which may arise later in your equipment. Even when the products are used within the guaranteed values, take into the consideration of incidence of break down and failure mode, possible to occur to semiconductor products. Measures on the systems such as redundant design, arresting the spread of fire or preventing glitch are recommended in order to prevent physical injury, fire, social damages, for example, by using the products. (7) When using products for which damp-proof packing is required, observe the conditions (including shelf life and amount of time let standing of unsealed items) agreed upon when specification sheets are individually exchanged. (8) This material may be not reprinted or reproduced whether wholly or partially, without the prior written permission of Matsushita Electric Industrial Co., Ltd.
2002 JUL

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