Voltage Regulators
1
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 pro-
vided 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.
■Features
•Wide operating supply voltage range: 1.8 V to 14 V
•High-precision reference voltage circuit: 1.27 V (allow-
ance: ± 3%)
•Supports control over a wide output frequency range:
20 kHz to 1 MHz
•Provides a fixed output current with minimal supply voltage fluctuations by using an external resistor to set the output
current with a totem pole structure in the output block.
•Large maximum output current of ± 50 mA
•Timer latch short-circuit protection circuit (charge current: 1.3 µA 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 µA 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 a 0.5 mm lead pitch 10 pin SO flat package (SSONF-10D)
•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
SSOP010-P-0225
Unit: mm
4.3±0.30
6.3±0.30
0.5±0.2
0.1±0.1
1
5
10
6
0.2±0.1
0.5
3.0±0.30
1.5±0.2
0.625±0.100.625±0.10
0.15
+0.1
–0.05
AN8016NSH Voltage Regulators
3
■Pin Descriptions
Pin No. Symbol Description
1IN−Error amplifier inverting input
2 S.C.P. Time constant capacitor connection for short-circuit protection
3 SS Soft-start time-constant capacitor connection
4 Off On/off control
5V
CC Supply voltage
6 Out Push-pull output
7 GND Ground
8 RB Output-current setting resistor connection pin
9 OSC Oscillator circuit timing resistor/capacitor connection pin
10 FB Error amplifier output
■Block Diagram
RB
8
Out
6
GND
7
Off 4
FB 10
IN−1
V
CC
5
OSC
9
SS 3
S.C.P. 2
U.V.L.O.
Error amp.
S.C.P.
comp.
Low level detector
comp.
High level detector comp.
Unlatch comp.
SS pin
Q
R
S
Triangular wave
generator
Latch
Reference
voltage supply
1.27 V
On/off
control
Active-high
Low level
clamp
30 kΩ
0.23 V 5 µA
V
CC
1.27 V 0.6 V
1.27 V
V
CC
Low level
clamp
1 µA
V
CC
PWM
0.7 V
0.2 V
1.27 V
0.23 V
Voltage Regulators AN8016NSH
3
Note) 1. Currents or voltages may not be applied to any pins not stipulated above. For circuit currents, a positive (+) value indicates
current flowing into the IC, and a negative (−) value indicates current flowing out of the IC.
2. Items other than the storage temperature, operating temperature, and power dissipation are all stipulated at Ta = 25°C.
3. *: Ta = 85°C. 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.
■Absolute Maximum Ratings
Parameter Symbol Rating Unit
Supply voltage VCC 15 V
Off pin allowable application voltage
VOFF 15 V
IN− pin allowable application voltage
VIN−VCC V
Out pin allowable application voltage
VOUT 15 V
Supply current ICC mA
Output source current ISO(OUT) −50 mA
Output sink current ISI(OUT) +50 mA
Power dissipation *PD115 mW
Operating temperature Topr −30 to +85 °C
Storage temperature Tstg −55 to +150 °C
■Recommended Operating Range
Parameter Symbol Conditions Unit
Supply voltage VCC 1.8 to 14 V
Off control pin voltage VOFF 0 to 14 V
Output source current ISO(OUT) −40 (min.) mA
Output sink current ISI(OUT) 40 (max.) mA
Timing resistance RT3 to 30 kΩ
Timing capacitance CT100 to 10 000 pF
Oscillator frequency fOUT 20 to 1 000 kHz
Short-circuit protection time CSCP 1 000 (min.) pF
constant setting capacitance
Output current setting resistance RB0 to 10k Ω
AN8016NSH Voltage Regulators
5
■Electrical Characteristics at VCC = 2.4 V, Ta = 25°C
Parameter Symbol Conditions Min Typ Max Unit
U.V.L.O. block
Circuit operation start voltage VUON 1.45 1.6 1.75 V
Error amplifier block
Input threshold voltage VTH Voltage follower 1.23 1.27 1.31 V
Line regulation with input fluctuation
VdV VCC = 1.8 V to 14 V 1.0 10 mV
Input bias current IB0.2 1.0 µA
High-level output voltage VEH 1.85 2.0 2.15 V
Low-level output voltage VEL 0.2 V
PWM comparator block
Output source current ISS VSS = 0.5 V −3.5 −5−6.5 µA
Output block
Oscillator frequency fOUT RT = 12 kΩ, CT = 330 pF 170 19 0 2 1 0 kHz
Maximum duty Dumax 75 80 85 %
High-level output voltage VOH IO = −15 mA, RB = 390 Ω1.4 V
Low-level output voltage VOL IO = 10 mA, RB = 390 Ω0.2 V
Output source current ISO(OUT) VO = 0.9 V, RB = 390 Ω−45 −32 −20 mA
Output sink current ISI(OUT) VO = 0.3 V, RB = 390 Ω20 mA
Pull-down resistor RO20 30 40 kΩ
Unlatch circuit block
Input threshold voltage VTHUL 0.13 0.20 0.27 V
Short-circuit protection circuit block
Input threshold voltage VTHPC 1.17 1.27 1.37 V
Input standby voltage VSTBY 60 120 mV
Input latch voltage VIN 40 120 mV
Charge current ICHG VSCP = 0.5 V −1.65 −1.3 − 0.95 µA
On/off control block
Input threshold voltage VON(TH) 0.8 1.0 1.3 V
Off mode SS pin voltage VOFF(SS) 0.13 0.27 V
Off mode S.C.P. pin voltage VOFF(SCP) 0.13 0.27 V
Whole device
Average consumption current ICC(AV) RB = 390 Ω, Duty = 50% 3.4 5.0 mA
Latch mode consumption current ICC(LA) RB = 390 Ω1.8 2.4 mA
Standby mode current ICC(SB) 5µA
Voltage Regulators AN8016NSH
5
■Electrical Characteristics at VCC = 2.4 V, Ta = 25°C (continued)
•Design reference data
Note) The characteristics listed below are theoretical values based on the IC design and are not guaranteed.
Parameter Symbol Conditions Min Typ Max Unit
U.V.L.O. block
Reset voltage VR0.8 V
Error amplifier block
VTH temperature characteristics VTHdT Ta = −30°C to +85°C− 0.5 + 0.5 %
Output source current ISO(FB) VFB = 0.5 V −40 µA
Output sink current ISI(FB) VFB = 0.5 V 2 mA
Open-loop gain AV80 dB
PWM comparator block
SS pin voltage VSS 1.22 V
Output block
RB pin voltage VBRB = 390 Ω0.13 V
Oscillator frequency supply fdV VCC = 1.8 V to 14 V −1+1%
voltage characteristics
Oscillator frequency temperature fdT Ta = −30°C to 85°C−3+3%
characteristics
Short-circuit protection circuit block
Comparator threshold voltage VTHL 1.27 V
On/off control block
On/Off pin current IOFF VOFF = 1.5 V 23 µA
AN8016NSH Voltage Regulators
7
■Terminal Equivalent Circuits
Pin No. Equivalent Circuit Description I/O
1IN−:I
Error amplifier inverting input.
2 S.C.P.: O
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 µA (typical).
However, the capacitor is charged with a time
constant determined by 0.23 V and a resistance
of 6 kΩ until the pin voltage reaches 0.23 V.
3 SS: I
Connection pin for the capacitor that determines
the PWM output soft start period. Note that the
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 µA (typical).
However, the capacitor is charged with a time
constant determined by 0.23 V and a resistor of
6 kΩ until the pin voltage reaches 0.23 V.
4 Off: I
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 µA or under.
5VCC:
Power supply connection.
Provide an operating supply voltage of 1.8 V
to 14 V.
300 Ω
V
CC
1.26 V
1
Q
S
Latch
1.27 V R
0.23 V
Low level detection comp.
To the
on/off
control
circuit
Output
cutoff
0.23 V
V
CC
3 kΩ
3 kΩ
2
0.23 V
Unlatch comp.
0.23 V
V
CC
C
T
PWM
3 kΩ
3 kΩ
S.C.P. pin
3
To the
on/off
control
circuit
30 kΩ
60 kΩ
4
Internal
circuit
start/stop
5
Voltage Regulators AN8016NSH
7
■Terminal Equivalent Circuits (continued)
Pin No. Equivalent Circuit Description I/O
6 Out: O
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-to-sample variations can be acquired by
connected an external resistor to the RB pin.
7 GND:
IC ground.
8 RB: I
Connection for the resistor that sets the output
current.
Use a resistor in the range 0 to 10 kΩ. Note that
the internal resistor R1 has a value of 1.0 kΩ.
Thus the pin voltage will be 0.13 V when RB is
390 Ω.
9 OSC: O
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 kΩ to 30 kΩ.
Use an oscillator frequency in the range
20 kHz to 1 MHz.
10 FB: O
Error amplifier output.
A source current is about −40 µA 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.
V
CC
I
O(SO)
6
30 kΩ
RB
7
VCC
8
R1 Out
Q
S
Latch
R
0.23 V
V
CC
9
10
V
CC
40 µA
PWM
C
2 mA
AN8016NSH Voltage Regulators
9
■Application Notes
[1] Power dissipation for the SSOP010-P-0225 package
PD Ta
400
386
100
200
154
115
300
287
00 25 50 75 85 100 125 150
Ambient temperature T
a
(°C)
Power dissipation P
D
(mW)
Independent IC
without a heat sink
R
th(j−a)
= 348°C/W
Glass epoxy printed
circuit board
(50 × 50 × t0.8 mm
3
)
R
th(j−a)
= 259°C/W
■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) × IOUT × Du + VCC × I CC < PD
Voltage Regulators AN8016NSH
9
■Application Notes (continued)
[2] Main characteristics
10
1 000
100 1 000 10 000
Oscillator frequency (kHz)
100
R
T
= 3 kΩ
R
T
= 6.2 kΩ
R
T
= 30 kΩ
R
T
= 12 kΩ
Timing capacitance (pF)
Timing capacitance Oscillator frequency Maximum duty Oscillator frequency
70
95
10 100 1 000
Oscillator frequency (kHz)
Maximum duty (%)
75
80
85
90 R
T
= 3 kΩ
R
T
= 6.2 kΩ
R
T
= 30 kΩ
R
T
= 12 kΩ
Error amplifier VTH temperature characteristics Oscillator frequency temperature characteristics
Maximum duty temperature characteristics
1.272
1.28
−30 −10 90
Ambient temperature T
a
(°C)
Voltage (V)
1.274
1.276
1.278
10 30 50 70 180
192
−30 −10 90
Ambient temperature T
a
(°C)
Oscillator frequency (kHz)
182
184
186
188
190
10 30 50 70
76
81
−30 −10 90
Ambient temperature T
a
(°C)
Maximum duty (%)
77
78
79
80
10 30 50 70
AN8016NSH Voltage Regulators
11
■Application Notes (continued)
[3] Timing charts (internal waveforms)
Maximum duty: 80%
Figure 1. PWM comparator operating waveforms
Figure 2. Short-circuit protection operating waveforms
Soft start operation
Low
Out pin waveform
High
0.2 V
0.4 V
0.6 V
0.7 V
1.22 V
1.27 V
2.4 V
2.0 V
Low
High
SS pin voltage
S.C.P. pin voltage
Off pin voltage
Supply voltage (VCC)
tPE
Triangular wave (CT)
Error amplifier output (FB)
Low
1.27 V
S.C.P. pin voltage 0.06 V
High
Low
High
0.6 V
1.27 V
2.0 V
Out pin waveform
Triangular wave (CT)
Error amplifier output (FB)
Dead time voltage (VDT)
Short-circuit protection
comparator threshold level
Short-circuit protection
comparator output
Power on
Voltage Regulators AN8016NSH
11
■Application Notes (continued)
[4] Functional descriptions
1. Reference voltage block
This circuit is composed of a band gap circuit, and outputs a 1.26-volt 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 resis-
tor connected to the OSC pin (pin 9). The oscillator
frequency can be set to any value by selecting appro-
priate 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 sig-
nal is provided to the inverting input of the PWM
comparator internally to the IC. Use the formulas
below for rough calculation of the oscillator fre-
quency.
fOSC ≈ −1≈ 0.75 ×1[Hz]
CT × RT × ln VOSCL CT × RT
VOSCH
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 ampli-
fier that detects and amplifies the DC-DC converter
output voltage, and inputs that signal to a PWM com-
parator. 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 re-
sistor and capacitor in series between the error am-
plifier output pin (pin 10) and the inverting input pin
(pin 1). The output voltage VOUT can be set by resis-
tor-dividing the output as shown in figure 2.
Figure 1. Triangular oscillator waveform
t
1
t
2
DischargeRapid
charge
T
V
OSCH
≈ 0.75 V
V
OSCL
≈ 0.2 V
FB
R1
R2
10
1.27 V To the PWM
comparator input
Error
amplifier
IN−1
V
OUT
V
OUT
= 1.27 ×
Figure 2. Connection method of error amplifier
R1 + R2
R2
AN8016NSH Voltage Regulators
13
■Application Notes (continued)
[4] Function descriptions (continued)
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 100%.
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 µA (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 µA
or under.
Voltage Regulators AN8016NSH
13
■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 short-
circuit protection comparator's non-inverting 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 kΩ,
and is charged from 230 mV to 1.26 V by a constant current of about 1.3 µA.
1) 0.06 ≤ VSCP [V] ≤ 0.23
VSCP = (0.23 − 0.06) × {1 − exp( −tPE1 )} [V]
6k · CS
tPE1 [s] ≈ 0.017 × CS [mF]
2) 0.23 ≤ VSCP [V] ≤ 1.26
1.27 V = 0.23 V + ICHG ×tPE2
CS
tPE2 [s] ≈ 0.80 × CS [µF]
∴ tPE [s] ≈ tPE1 + tPE2 ≈ 0.817 × CS [µF]
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.
Figure 3. S.C.P. pin charging waveform
t
PE1
t
PE2
V
SCP
[V]
t [s]
Short-circuit detection time t
PE
0.06
0.23
1.27
FB 10
1.27 V
Q1
Error amp. S.C.P. comp.
IN−1
S.C.P. 2
Figure 4. Short-circuit protection circuit
1.27 V
High level detection comparator
3 kΩ
3 kΩ
1 µA
0.23 V
Internal reference
Output
shutoff
VCC
CS
U.V.L.O.
Q
R
S
Latch
On/off
control
1.27 V
AN8016NSH Voltage Regulators
15
■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
kΩ, and is charged from 230 mV to 1.22 V by a constant current of about 5 µA.
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) × {1 − exp( −tSS1 )} [V]
6k · CS
tPE1 [s] ≈ 0.017 × CS [mF]
2) 0.23 ≤ VSCP [V] ≤ 1.26
0.52 V = 0.23 V + ICHG ×tSS2
CS
tPE2 [s] ≈ 0.058 × CS [µF]
∴ tSS [s] ≈ tSS1 + tSS2 ≈ 0.075 × CS [µF]
t
SS2
t
SS1
OSC
t (s)
Figure 5. Soft start operating waveforms
Duty: 50%
Soft start time
0.06
0.23
0.52
0.75
1.22
(V)
FB
SS
DC-DC converter output voltage
Voltage Regulators AN8016NSH
15
■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 dead- time
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.
2) Note that it is not possible to operate this IC (the AN8016NSH) with the two-channel AN8017SA/AN8018SA
together in parallel synchronous mode.
65
74
83
92
101
AN8016NSH Master
SS
Figure 6. Slave operation circuit example
S.C.P.
OSC
65
74
83
92
101
AN8016NSH Slave
SSS.C.P.
65
74
83
92
101
AN8016NSH Master
NG
Figure 7. Slave operation circuit example
S.C.P.
OSC
65
74
83
92
101
AN8016NSH Slave
SS
AN8016NSH Voltage Regulators
17
■Application Circuit Examples
[1] Application circuit (Step-up circuit)
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 pro-
vide a constant-current (50 mA maximum) output
source current. Furthermore, it has a sink current ca-
pacity 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 pro-
vide 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 volt-
age of twice the input voltage to the IC's VCC pin.
RB8SS 3
GND7Off 4
FB10IN−1
OSC9S.C.P. 2
Out6VCC 5
AN8016NSH
2SD2408
SBD
MA2Q738 (MA738∗)
1 kΩ
0.1 µF
6.8 kΩ20 kΩ
390 Ω
12 kΩ
333 pF
330 pF
103 pF 1 µF
47 µH
1.5 V
10 µF
Q1
VIN
3 V
VOUT
5 V
200 mA
Note) ∗: Former part number
SBD
V
IN
Figure 1. Output boosting circuit
Figure 2. Gate drive voltage boosting technique
Out
V
OUT
6
SBD
V
IN
V
CC
V
OUT
V
CC
≈ 2 × V
IN
− V
D
SBD
Out
6
5
Voltage Regulators AN8016NSH
17
■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.
[3] Evaluation board
RB8
SS 3
GND7
Off 4
FB10IN−1
OSC9
S.C.P. 2
Out6VCC 5
AN8016NSH
SBD
24
kΩC3
R2
Q1
VIN VOUT
GND
(1)
(2)
(3) (5)
(4)
C3
C4
C5
R6
R5
R4
R3
C1C2
C6
GND
Off V
IN
V
OUT
L1
BCE
Q1
SBD
+
+
R1
R2 AN8016NSH
DC-DC CONVERTER BOARD
