AN8016NSH PANASONIC
Document overview
- Manufacturer or author: Provided By digicamel.com
- PDF pages: 17
Technical content
Single-channel 1.8-volt step-up DC-DC converter control IC n 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. n 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 mA typical)
- On/off control function (active-high, standby current: 5 mA 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. n 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 0.2–0.1 0.5 3.0–0.30 1.5–0.2 0.15 +0.1 –0.05
AN8016NSH Voltage Regulators n Pin Descriptions Pin No. Symbol Description 1I N - 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
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
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 QR S Triangular wave generator Latch Reference voltage supply 1.27 V On/off control Active-high Low level clamp 30 kW
0.23 V 5 mA
1.27 V 0.6 V 1.27 V V CC Low level clamp 1 mA V CC PWM 0.7 V 0.2 V 1.27 V 0.23 V
Voltage Regulators AN8016NSH 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. n Absolute Maximum Ratings Parameter Symbol Rating Unit Supply voltage V CC 15 V Off pin allowable application voltage V OFF 15 V IN- pin allowable application voltage V IN- V CC V Out pin allowable application voltage V OUT 15 V Supply current I CC ¾ mA Output source current I SO(OUT) -50 mA Output sink current I SI(OUT) +50 mA Power dissipation * PD 115 mW Operating temperature T opr -30 to +85 °C Storage temperature T stg -55 to +150 °C n Recommended Operating Range Parameter Symbol Conditions Unit Supply voltage V CC 1.8 to 14 V Off control pin voltage V OFF 0 to 14 V Output source current I SO(OUT) -40 (min.) mA Output sink current I SI(OUT) 40 (max.) mA Timing resistance R T 3 to 30 k W Timing capacitance C T 100 to 10 000 pF Oscillator frequency f OUT 20 to 1 000 kHz Short-circuit protection time CSCP 1 000 (min.) pF constant setting capacitance Output current setting resistance RB 0 to 10k W
AN8016NSH Voltage Regulators n 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 V TH Voltage follower 1.23 1.27 1.31 V Line regulation with input fluctuationV dV V CC = 1.8 V to 14 V ¾ 1.0 10 mV Input bias current I B ¾ 0.2 1.0 mA High-level output voltage V EH 1.85 2.0 2.15 V Low-level output voltage V EL ¾¾ 0.2 V PWM comparator block Output source current I SS V SS = 0.5 V -3.5 -5 -6.5 mA Output block Oscillator frequency f OUT R T = 12 kW , CT = 330 pF 170 190 210 kHz Maximum duty Du max 75 80 85 % High-level output voltage V OH IO = -15 mA, RB = 390 W 1.4 ¾¾ V Low-level output voltage V OL IO = 10 mA, RB = 390 W¾ ¾ 0.2 V Output source current I SO(OUT) V O = 0.9 V, RB = 390 W- 45 -32 -20 mA Output sink current I SI(OUT) V O = 0.3 V, RB = 390 W 20 ¾¾ mA Pull-down resistor R O 20 30 40 k W Unlatch circuit block Input threshold voltage V THUL 0.13 0.20 0.27 V Short-circuit protection circuit block Input threshold voltage V THPC 1.17 1.27 1.37 V Input standby voltage V STBY ¾ 60 120 mV Input latch voltage V IN ¾ 40 120 mV Charge current I CHG V SCP = 0.5 V -1.65 -1.3 - 0.95 mA On/off control block Input threshold voltage V ON(TH) 0.8 1.0 1.3 V Off mode SS pin voltage V OFF(SS) 0.13 ¾ 0.27 V Whole device Average consumption current ICC(AV) R B = 390 W , Duty = 50% ¾ 3.4 5.0 mA Latch mode consumption current ICC(LA) R B = 390 W¾ 1.8 2.4 mA Standby mode current I CC(SB) ¾¾ 5 mA
Voltage Regulators AN8016NSH n 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 V R 0.8 V Error amplifier block V TH temperature characteristics VTHdT Ta = -30°C to +85°C - 0.5 + 0.5 % Output source current I SO(FB) V FB = 0.5 V -40 mA Output sink current I SI(FB) V FB = 0.5 V 2 mA Open-loop gain A V 80 dB PWM comparator block SS pin voltage V SS 1.22 V Output block RB pin voltage V B R B = 390 W 0.13 V Oscillator frequency supply f dV V CC = 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 I OFF V OFF = 1.5 V 23 mA
AN8016NSH Voltage Regulators n Terminal Equivalent Circuits Pin No. Equivalent Circuit Description I/O 1I N -: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 I CHG is 1.3 mA (typical). However, the capacitor is charged with a time constant determined by 0.23 V and a resistance of 6 kW 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 I SS is 5 mA (typical). However, the capacitor is charged with a time constant determined by 0.23 V and a resistor of 6 kW 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 mA or under.
5 V CC : ¾
Power supply connection. Provide an operating supply voltage of 1.8 V to 14 V. 300 W V CC 1.26 V QS 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 kW 3 kW 0.23 V Unlatch comp. 0.23 V V CC C T PWM 3 kW 3 kW S.C.P. pin3 To the on/off control circuit 30 kW 60 kW Internal circuit start/stop
Voltage Regulators AN8016NSH n 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: ¾
IC ground.
8 RB: I
Connection for the resistor that sets the output current. Use a resistor in the range 0 to 10 kW . Note that the internal resistor R1 has a value of 1.0 kW . Thus the pin voltage will be 0.13 V when R B is 390 W .
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 kW to 30 kW . Use an oscillator frequency in the range 20 kHz to 1 MHz.
10 FB: O
Error amplifier output. A source current is about -40 mA 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 IO(SO) 30 kW RB V CC Out QS Latch R0.23 V V CC V CC 40 mA PWMC 2 mA
AN8016NSH Voltage Regulators n Application Notes [1] Power dissipation for the SSOP010-P-0225 package PD ¾ Ta 400 386 100 200 154 115 300 287 0 25 50 75 85 100 125 150 Ambient temperature Ta (°C) Power dissipation PD (mW) Independent IC without a heat sink R th(j-a) = 348°C/W Glass epoxy printed circuit board (50 · 50 · t0.8 mm R th(j-a) = 259°C/W n 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 · ICC < PD
Voltage Regulators AN8016NSH n Application Notes (continued) [2] Main characteristics 1 000 100 1 000 10 000 Oscillator frequency (kHz) 100 R T = 3 kW R T = 6.2 kW R T = 30 kW R T = 12 kW Timing capacitance (pF) Timing capacitance ¾ Oscillator frequency Maximum duty ¾ Oscillator frequency 10 100 1 000 Oscillator frequency (kHz) Maximum duty (%)
90 R T = 3 kW
R T = 6.2 kW R T = 30 kW R T = 12 kW Error amplifier VTH temperature characteristics Oscillator frequency temperature characteristics Maximum duty temperature characteristics 1.272 1.28 -30 -10 90 Ambient temperature Ta (°C) V oltage (V) 1.274 1.276 1.278 10 30 50 70 180 192 -30 -10 90 Ambient temperature Ta (°C) Oscillator frequency (kHz) 182 184 186 188 190 10 30 50 70 -30 -10 90 Ambient temperature Ta (°C) Maximum duty (%) 10 30 50 70
voltage. This reference voltage is stabilized when the supply voltage is 1.8 V or higher.
- Triangular wave generator
provided in the main characteristics section. tor-dividing the output as shown in figure 2. Figure 1. Triangular oscillator waveform
1.27 V To the PWM
Figure 2. Connection method of error amplifier
AN8016NSH Voltage Regulators n 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%. 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 (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 mA (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 mA or under.
kW , and is charged from 230 mV to 1.22 V by a constant current of about 5 mA. The following formulas express the soft start time for the duty of up to 50%. Figure 5. Soft start operating waveforms
The figure shows a step-up circuit that converts a 3 V input to a 5 V output. n-channel MOSFET in above circuit.
- Select an n-channel MOSFET with a low input
- Use an n-channel MOSFET of a low gate threshold
with an adequately low on-resistance must be used.
390 W12 kW
Figure 1. Output boosting circuit Figure 2. Gate drive voltage boosting technique
Voltage Regulators AN8016NSH n 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 RB8SS 3 GND7Off 4 FB10IN- 1 OSC9S.C.P. 2 Out6V CC 5 AN8016NSH SBD kW V IN V OUT GND (1) (2) (3) (5) (4) R3C1C2 GND Off V IN V OUT BCE SBD AN8016NSH DC-DC CONVERTER BOARD