AN8014S PANASONIC
Document overview
- Manufacturer or author: Provided By digicamel.com
- PDF pages: 18
Technical content
Step-down, step-up, or inverting DC-DC converter control IC n Overview The AN8014S is a single-channel PWM DC-DC converter control IC. This IC can provide any one output type from among step-down, step-up and inverting output. Allowing n-channel power MOSFET direct driv- ing, the AN8014S is ideal for high-efficiency power supplies. n Features
- Wide operating supply voltage range (3.6 V to 34 V) (The voltage is limited within a range between 3.6 V and 17 V if it is connected to a step-down volt- age circuit.) Totem pole output circuit: output peak current (–1 A)
- On-chip pulse-by-pulse overcurrent detection and protection circuit Threshold voltage VCC - 0.095 V typical
- On-chip bootstrap circuit (allowing n-channel MOSFET direct driving.)
- On-chip under-voltage lock-out circuit (U.V.L.O.)
- On-chip on/off function (active-high control input, standby current of maximum 5 mA)
- On-chip timer latch short-circuit protection circuit
- Maximum oscillator frequency (500 kHz) n Applications
- DC-DC switching power supply n Block Diagram SOP016-P-0225A Unit: mm 0.3 (0° to 10°) (0.15) 10.1±0.3 4.2±0.3 6.5±0.3 16 9 1.27(0.605) Seating plane Seating plane 0.40±0.25 0.1±0.1 1.5±0.2 Error amp. V REF 2.5V R S Q Q R S Q Out CLM10 IN+ IN- OFF 5S.C.P. S.C.P. comp. V CC CB RT CT DTC V REF PGND FB SGND PWM comp. U.V.L.O. Latch Latch Boot strap RQS 1 mA 10 mA On/off active-high Constant current source Triangular wave OSC
AN8014S Voltage regulators n Absolute Maximum Ratings Parameter Symbol Rating Unit Supply voltage V CC 35 V Supply current I CC ¾ mA Power dissipation *2 PD 143 mW Operating ambient temperature *1 Topr -30 to +85 °C Storage temperature *1 Tstg -40 to +125 °C On/off pin allowable application voltage VON/OFF V CC V Error amplifier allowable input voltage VI - 0.3 to VREF V DTC pin allowable application voltage VDTC - 0.3 to VREF V Out pin allowable application voltage VOUT 35 V Out pin constant output current I O –100 mA Out pin peak output current I O(Peak) –1 000 mA CB pin allowable application voltage V CB 35 V CB pin constant output current I CB -100, 150 mA CB pin peak output current I CBP -500, 1 000 mA CLM pin allowable application voltage VCLM V CC V Note) 1.*1: Except for the operating ambient temperature and storage temperature, all ratings are for Ta = 25°C. *2: At Ta = 85°C 2. 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. n Recommended Operating Range Parameter Symbol Range Unit Supply voltage V CC Step-up circuit system 3.6 to 34 V Step-down circuit system 3.6 to 17 n Pin Descriptions Pin No. Description
9 Not connected
10 Overcurrent protection input
11 Signal ground
12 Output stage ground
13 Totem pole type output
14 Bootstrap output
15 Supply voltage
16 On/off control
Pin No. Description
1 Internal reference output
2 Oscillator timing resistor connection
3 Oscillator timing capacitor connection
4 Dead-time control
5 Capacitance connection for short-circuit
6 Error amplifier noninverting input
7 Error amplifier inverting input
8 Error amplifier output
Voltage regulators AN8014S n Electrical Characteristics at VCC = 12 V, Ta = 25°C Parameter Symbol Conditions Min Typ Max Unit Reference voltage block Output voltage V REF IREF = -1 mA 2.522 2.6 2.678 V Line regulation with input fluctuationLine V CC = 3.6 V to 34 V ¾ 16 25 mV Load regulation Load I REF = - 0.1 mA to -1 mA ¾ 11 0 m V U.V.L.O. block Circuit operation start voltage VUON ¾ 2.8 3.1 3.4 V Hysteresis width V HYS ¾ 60 140 180 mV Error amplifier block Input offset voltage V IO ¾- 6 ¾ 6m V Input bias current I B ¾- 500 -25 ¾ nA Common-mode input voltage range VICR ¾- 0.1 ¾ 0.8 V High-level output voltage V EH ¾ V REF V REF ¾ V - 0.3 - 0.1 Low-level output voltage V EL ¾¾ 0.1 0.3 V Dead-time control circuit block Input current I DTC ¾- 15.8 -13.2 -10.6 mA Low-level input threshold voltage VDT-L Duty 0% ¾ 0.45 0.65 V High-level input threshold voltage VDT-H Duty 100% 1.2 1.4 ¾ V Output block Oscillator frequency f OUT C T = 120 pF, RT = 15 kW 196 218 240 kHz Output duty Du R DTC = 75 kW 47 52 57 % Low-level output voltage V OL IO = 70 mA ¾ 1.0 1.3 V High-level output voltage V OH IO = -70 mA V CB V CB ¾ V -2.0 -1.0 Bootstrap circuit block Input standby voltage V INCB ICB = -70 mA V CC V CC V CC V -1.2 -1.0 - 0.8 Short-circuit protection circuit block Input threshold voltage V THPC ¾ 0.70 0.75 0.80 V Input standby voltage V STBY ¾¾ 30 120 mV Input latch voltage V IN ¾¾ 30 120 mV Charge current I CHG ¾- 2.76 -2.30 -1.84 mA On/off control block Threshold voltage V TH ¾ 0.8 ¾ 2.0 V Overcurrent protection block Threshold voltage V CLM ¾ V CC V CC V CC V
AN8014S Voltage regulators
- Design reference data Note) The characteristics listed below are theoretical values based on the IC design and are not guaranteed. Parameter Symbol Conditions Limit Unit Reference voltage block Output voltage temperature V TC1 Ta = -30°C to +25°C –1% characteristics 1 Output voltage temperature V TC2 Ta = 25°C to 85°C –1% characteristics 2 Output short-circuit current I OS ¾- 40 mA Error amplifier block Output sink current I SINK V FB = 0.9 V 8 mA Output source current I SOURCE V FB = 0.9 V -110 mA Open-loop gain A G ¾ 70 dB Output block Frequency supply voltage f dV fOUT = 200 kHz, –3% characteristics V CC = 3.6 V to 34 V Frequency temperature f dT1 fOUT = 200 kHz, –9% characteristics 1 T a = -30°C to +25°C Frequency temperature f dT2 fOUT = 200 kHz, –9% characteristics 2 T a = 25°C to 85°C Oscillator block RT pin voltage V RT ¾ 0.4 V Short-circuit protection circuit block Comparator threshold voltage V THL ¾ 1.87 V Overcurrent protection circuit block Delay time t DLY ¾ 200 ns n Electrical Characteristics at VCC = 12 V, Ta = 25°C (continued) Parameter Symbol Conditions Min Typ Max Unit Whole device Total consumption current I CC ¾¾ 5.0 7.0 mA Standby current I CC(SB) ¾¾ ¾ 5 mA
Voltage regulators AN8014S Pin No. I / O Equivalent circuit Description 1O V REF : Outputs the reference voltage
2.6 V (allowance: 3%)
Incorporating short-circuit protection against ground. 2 ¾ RT: Connection for the timing resistor which decides the oscillator frequency. Use a re- sistor in the range 5.1 kW to 30 kW . The pin voltage is approx. 0.4 V. 3 ¾ CT: Connection for the timing capacitor which decides the oscillator frequency. Use a ca- pacitor in the range 100 pF to 10 000 pF. For the oscillator frequency setting, refer to the "Application Notes, [1] Function descriptions" section. Use an oscillator fre- quency in the range 5 kHz to 500 kHz. 4 ¾ DTC: Connection for a resistor and a capacitor that set the dead-time and soft start period of PWM output. Input current I DTC is decided by the timing resistor RT which controls sample to sample variations and temperature variations. It is approx. -13.2 mA when R T = 15 kW . IDTC = VRT · 1 [A]R T 2 n Terminal Equivalent Circuits V CC V REF 100 W DTC S.C.P. V REF RT(» 0.4 V) OSC comp. To PWM input V REF CT IO 2IO V REF RT C DTC IDTC R DTC DTC 4 PWM comparator input
AN8014S Voltage regulators Pin No. I / O Equivalent circuit Description 5 ¾ S.C.P.: Connection for the capacitor that sets the soft start period and 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 decided by the timing resistor RT which controls sample to sample variations and temperature varia- tions. It is approx. -2.3 mA when R T = 15 kW . ICHG = VRT · 1 [A]R T 11 6I I N +: Noninverting input to the error amplifier. Use the common-mode input in the range - 0.1 V to +0.8 V. 7I I N -: Inverting input to the error amplifier. Use the common-mode input in the range - 0.1 V to +0.8 V.
8 O FB:
Output from the error amplifier. The source current is approx. -110 mA and sink current is approx. 8 mA. Correct the frequency characteristics of the gain and the phase by connecting a re- sistor and a capacitor between this pin and IN- pin. 9 ¾¾ N.C.: Not connected.
10 I CLM:
Detects the overcurrent state in switching transistor. Insert a resistor with a low resistance between this pin and VCC to detect overcurrent states. When this pin falls to a level 95 mV or more lower than VCC , the PWM output is turned off for that period thus narrowing the width of the on-period. (This implements a pulse-by-pulse overcurrent protection technique.) n Terminal Equivalent Circuits (continued) 7 6 V REF IN- IN+ 50 mA 50 mA 10V CC 0.1 V CLM comp. CLM V REF FB Sink current Source current R S Q V REF S.C.P.5 0.75 V U.V .L.O. output ICHG Latch
Voltage regulators AN8014S Pin No. I / O Equivalent circuit Description 11 ¾ SGND: Signal ground. 12 ¾ GND: Output stage ground.
13 O Out:
Totem pole output. A constant output current of –100 mA or a peak output current of –1 A can be ob- tained.
14 O CB:
Bootstrap output. Connect a bootstrap capacitor between this pin and the n-channel MOSFET source- side pin of the switching element when using a step-down voltage circuit. Short-circuit this pin and the V CC pin when using a step-up voltage circuit. 15 I V CC : Power supply.
16 I OFF :
Controls the on/off state. When the input is high: normal operation (VOFF > 2.0 V) When the input is low: standby mode (VOFF < 0.8 V) In standby mode, the total current consu- mption is held to under 10 mA. n Terminal Equivalent Circuits (continued)
11 SGND
12 GND
[1] Function descriptions 1. Reference voltage block This block is composed of the band gap circuit and outputs the temperature compensated reference voltage (2.6 V) to the VREF pin (pin 1). The reference voltage is stabilized when the supply voltage is 3.6 V or more and used as the operating power supply in IC. It is possible to take out a load current of up to -1 mA.
2.0 V or more, the internal reference voltage rises thereby starting the control operation. element (n-channel MOSFET) will be turned on. DTC on the DTC pin (pin 5) as shown in figure 4. connecting the DTC and GND pins through the external resistor RDTC . 100% at VDTC of 1.32 V typical. triangular wave vary with the oscillator frequency. Figure 4. Setting the dead-time V CTH is approximately 1.32 V, VCTH is approximately 0.44 V, and VRT is approximately 0.4 V. Therefore, the following are obtained. values may occur, in which case adjust the values on the mounting substrate. converters can be prevented.
Voltage regulators AN8014S n Application Notes (continued) [1] Function descriptions (continued) 9. Bootstrap circuit of output block (continued) 2) N-channel MOSFET (M1) turn-on time: t2 When the PWM comparator output is inverted, the Out pin (pin 13) output changes into a high level. The Out pin voltage VO rises toward the CB pin voltage. V O = VCB - VCE (sat) Then the voltage between the gate and source of the M1 is obtained from the following. V GS = VO +V F When the Out pin voltage VO is the same as or higher than the gate threshold voltage VTH , the M1 turns on. Then the M1 source-side voltage rises up to the voltage expressed by the following. V S = VCC - VDS(ON) The bootstrap capacitor CB is connected to the source side and CB pin of the M1. Therefore, the CB pin voltage rises according to the M1 source-side voltage due to capacitor coupling. VCB is expressed by the following formula. V CB = VS + VCC - VD1 + VF = 2 · VCC - VD1 + VDS(ON) + VF 3) N-channel MOSFET (M1) turn-off time: t3 The Out pin voltage turns off after rising to the saturation voltage of the AN8014S's internal transistor Q1. The M1 source-side voltage drops to -V F . The CB pin voltage drops to VCC - VD1 or below due to capacitive coupling. Then the M1 will be in the state described in the above 1). [2] Bootstrap circuit usage notes 1. Operating voltage range for step-down circuit Just like what described previously, if a step-down circuit is in DC-DC converter control, the CB pin (pin 14) voltage will be approximately twice as high as VCC when the n-channel MOSFET as a switching element is turned on. The allowable voltage applied to the CB pin is 35 V. Therefore the operating supply voltage must be within a range between 3.6 V and 17 V. V CB = 2 · VCC - VD1 - VDS (ON) + VF < 35 [V] V CC < 35 + VD1 + VDS (ON) - VF [V] < 17 [V]2 2. Value setting of bootstrap capacitor The bootstrap capacitor raises the CB pin voltage to VCC or higher due to capacitor coupling to the source side of the n-channel MOSFET when the n-channel MOSFET is turned on. At that time bootstrap capacitor is dis- charged by n-channel MOSFET gate-drive-current. If the capacitance of the bootstrap capacitor is too low, an increase in switching loss will result, which will reduce the efficiency. Therefore, the capacitance must be large enough in comparison with the gate input capacitance of the n- channel MOSFET. Refer to the following. C B > Ciss Determine the best value by testing on the printed circuit board for mounting. 3. CB pin connection for step-up circuit If a step-up circuit is in DC-DC converter control, no bootstrap circuit is required because the source side of the n-channel MOSFET is grounded. Therefore, short-circuit the CB pin (pin 14) and the VCC pin (pin15). Thus, the operating supply voltage range in the step-up circuit method is between 3.6 V and 34 V.
Turned on in the next cycle. Figure 3. Waveforms of the pulse-by-pulse overcurrent protection operation
AN8014S Voltage regulators n Application Notes (continued) [5] Main characteristics Internal reference voltage temperature characteristics Oscillator frequency temperature characteristics 2.60 2.61 2.62 2.63 -50 100 12550 7502 5-25 Ambient temperature Ta (°C) Internal reference voltage VREF (V) 195 205 215 225 200 210 220 -50 100 12550 7502 5-25 Ambient temperature Ta (°C) Oscillator frequency fOUT (kHz) Output duty ratio ¾ DTC pin voltage Output duty ratio temperature characteristics Oscillator frequency ¾ Timing capacitance Output peak current ¾ COut 100 DTC pin voltage VDTC (V) Output duty ratio Du (%) -50 100 12550 7502 5-25 Ambient temperature Ta (°C) Output duty ratio Du (%) 100 1 000 10 000 10 100 1 000 10 000 Timing capacitance CT (pF) Oscillator frequency fOUT (kHz) R T = 15 kW R T = 5.1 kW 0.2 0.4 0.6 0.1 0.3 0.5 1 000 10 000 V CC = 12 V R OUT = 10 W 5 000 Value of output connection capacitor COUT (pF) Output peak current IPeak (A)
Voltage regulators AN8014S n Application Circuit Examples 1. DC-DC converter control (Example of step-down circuit) 2. DC-DC converter control (Example of step-up circuit) S.C.P. SGND V REF DTC CT RT PGND FB V 1 0.1 mF 100 mF 0.12 mF 0.039 mF f = 200 kHz 47 mF1 000 pF 15 kW 62 kW 11 kW100 kW 0.1 W 33 W 10 W 9.1 kW 75 kW 120 pF 3.9 kW In 12 V Out 5 V CLM V CC CB In Out IN+ IN- V REF 2.5V R S Q Q R S Q S.C.P. comp. PWM comp. U.V.L.O. Latch Latch Boot strap RQS 1 mA 10 mAOFF Error amp. On/off active-high Constant current source Triangular wave OSC S.C.P. SGND V REF DTC CT RT PGND FB V 1 In Out CLM CB V CC In Out IN+ IN- V REF 2.5V R S Q Q R S Q S.C.P. comp. PWM comp. U.V.L.O. Latch Latch Boot strap RQS 1 mA 10 mAOFF Error amp. On/off active-high Constant current source Triangular wave OSC
AN8014S Voltage regulators n Application Circuit Examples (continued) 3. DC-DC converter control (Example of polarity-inverting circuit) OFF S.C.P. SGND V REF DTC CT RT PGND FB V 1 In Out CLM V CC In Out CB IN+ IN- V REF V 1 V REF 2.5V R S Q Q R S Q S.C.P. comp. PWM comp. U.V.L.O. Latch Latch Boot strap RQS 1 mA 10 mA Error amp. On/off active-high Constant current source Triangular wave OSC