AT1380A AIMTRON | Alldatasheet

Document overview

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Technical content

Features

  • 2.5 to 15 V supply voltage operating range.
  • Low current consumption: 6 mA in operation, 1 µA or less in stand-by.
  • 20 kHz to 1 MHz operation frequency range.
  • Provides a fixed output current with minimal supply voltage fluctuations by using an external resistor to set the output current.
  • Totem-pole output.
  • Built-in soft start circuit.
  • Built-in timer-latch short circuit detection and protection circuit (SCP).

Applications

  • LCD Displays
  • PDAs
  • Digital Still Cameras General Description The AT1380A is a single-channel PWM control IC for DC/DC conversion with soft start function and short circuit detection. Adjustable soft start is programmed with an exte rnal capacitor on SCP pin. The AT1380A is ideal for up, down and fly- back conversion. Block Diagram Aimtron reserves the right without notice to change this circuitry and specifications.

Preliminary Product Information S w i t c h i n g R e g u l a t o r C o n t r o l l e r f o r L C D B i a s Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw Pin Configuration

Ordering Information

Part number Package Marking AT1380AS SOP8 AT1380AS AT1380AS_PBF SOP8, Pb-Free AT1380AS, Date Code with one bottom line AT1380AS_GRE SOP8, Green AT1380AS, Date Code with two bottom line AT1380AP TSSOP8 AT1380AP AT1380AP_PBF TSSOP8, Pb-Free AT1380AP, Date Code with one bottom line AT1380AP_GRE TSSOP8, Green AT1380AP, Date Code with two bottom line Pin Description Pin No. Symbol I/O Description

1 IN- I Error amplifier inverting input

2 SCP — Soft start and SCP setting capacitor connection

3 VCC — Power supply

4 BR/CTL I Output current setting

5 OUT O Totem-pole type output

6G N D — G r o u n d

7 OSC — Capacitor and resistor connection pin for setting the oscillation

8 FB O Error amplifier output

Preliminary Product Information S w i t c h i n g R e g u l a t o r C o n t r o l l e r f o r L C D B i a s Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw Absolute Maximum Ratings (Ta=+250C) Rated ValueParameter Symbol Condition Min. Max. Unit Power supply voltage V CC —— 1 5 V Output source current I O + —— - 5 0 m A Output sink current I O - —— 5 0 m A PD SOP-8, Ta ≦+25°C —5 7 0 m W Allowable dissipation PD TSSOP-8, Ta ≦+25°C —4 3 0 m W Operating temperature T OP —- 3 0 + 8 5 0C Storage temperature T stg — -55 +125 0C ESD Classification MIL-STD-883 Class 2 * : When mounted on a 10 cm square double-sided epoxy board WARNING: Do not exceed these ratings. IC devices can be permanently damaged by stress (voltage, current, temperature, etc.) in excess of absolute maximum ratings. Recommended Operating Conditions (Ta=+250C) ValuesParameter Symbol Min. Typ. Max. Unit Power supply voltage V CC 2.5 -- 13.5 Ｖ Error amplifier input voltage V I -0.2 -- 1.0 Ｖ BR/CTL pin input voltage V BR -0.2 -- V CC Ｖ Output source current I O + -20 -- -- ｍＡ Output sink current I O - -- -- 40 ｍＡ SCP pin capacitance C PE -- 0.1 -- μＦ Phase compensation capacitance C P -- 0.1 -- μＦ Output current setting resistance R B 150 390 5000 Ω Timing resistance R T 1.0 3.0 10.0 ｋΩ Timing capacitance C T 100 270 10000 pF Oscillation frequency f OSC 10 500 1000 kHz Operating temperature T OP -30 +25 +85 °C WARNING: Recommended operating conditions are normal operating ranges for the IC device. All the device’s electrical characteristics are warranted for operation within these ranges. Use IC devices only within the recommended operating conditions. Operation outside these ranges may adversely affect the reliability and can result in device failure.

Preliminary Product Information S w i t c h i n g R e g u l a t o r C o n t r o l l e r f o r L C D B i a s Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw

Electrical Characteristics

(V CC=+3.0V , Ta=+250C) ValuesParameter Symbol Condition Min. Typ. Max. Unit Reset voltage for falling Vcc. OUT remains off if Vcc is below this level. VR -- 1.8 1.9 VVCC Under voltage Lockout (U.V .L.O.) Startup voltage for rising Vcc. VTH 2.4 2.5 2.6 V Charging current I CS VSCP=0V -1.5 -1.0 -0.7 μA Soft start V oltage at soft start completion Vts -- 0.7 0.8 0.9 V Charging current I CPC VSCP=0V -1.5 -1.0 -0.7 μAShort circuit Oscillation frequency f OSC RT=3kΩ, CT=270pF 400 500 600 kHz Frequency input Stability f∆V VCC=2.5V to 13.5V -- 2 10 %Sawtooth waveform oscillator (OSC) Frequency variation with temperature f∆T Ta =-300C to 850C- - 5 - - % Input threshold V oltage VT VFB = 450mV 480 500 520 mV VT input stability V T∆V VCC=2V to 13.5V -- 5 20 mV VT variation with Temperature VT∆T Ta = -300C to 850C- - 1 - - % Input bias current I B VIN = 0V -1.0 -0.2 1.0 μA V oltage gain A V -- 70 100 145 V/V Frequency bandwidth BW A V = 0 dB -- 6 -- MHz VOM + 0.78 0.87 -- VMaximum output voltage range VOM -- 0.05 0.2 V Output source current I OM + -- -40 -24 μA Error amplifier Output sink current I OM VFB = 450mV 24 40 -- μA Idle period adjustment section Maximum duty cycle T DUTY RT=3.3kΩ, CT=270pF fOSC = 500KHz 75 -- 85 % VOH1 RB= 390Ω, IO= -15 mA 1.0 1.2 -- V VOH2 RB= 750Ω, VCC = 3.0V IO= -10 mA 0.8 1.0 -- V VOL1 RB= 390Ω, IO= -15 mA -- 0.1 0.2 V Output voltage VOL2 RB= 750Ω, VCC = 3.0V IO= -10 mA -- 0.1 0.2 V Output source current I O Output sink current I O - RB= 390Ω, VO = 0.3V 40 70 -- mA Output section Pull down resistance R O -- 20 30 40 ｋΩ

Preliminary Product Information S w i t c h i n g R e g u l a t o r C o n t r o l l e r f o r L C D B i a s Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw Pin voltage V BR RB= 390Ω 0.10 0.19 0.25 V Input off condition I OFF -20 -- 0 μA Input on condition I ON -- -- -45 μA Output current Setting section/ Control section Pin current range I BR -1.8 -- -0.1 ｍＡ Stand-by current I CCS BR/CTL pin open or VCC -- -- 1 μA Entire device Average supply current I CC RB= 390, VCC =2.5~13.5V -- 6 10.0 ｍＡ Timing Chart

Preliminary Product Information S w i t c h i n g R e g u l a t o r C o n t r o l l e r f o r L C D B i a s Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw Typical Application Schematic

Preliminary Product Information S w i t c h i n g R e g u l a t o r C o n t r o l l e r f o r L C D B i a s Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw

Figure 1. Soft-Start SCP circuit capacitor CS is charged from 0V at a constant current of 1µA. external capacitor CS will start to charge because the error amplifier output (FB pin) is fixed at V OM+. turned off or the power supply is restarted.

Preliminary Product Information S w i t c h i n g R e g u l a t o r C o n t r o l l e r f o r L C D B i a s Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw Setting Oscillating Frequency The oscillator circuit generates a triangular sawtooth wave with a peak of 0.8V and a trough of 0.1V using the timing capacitor (CT) and the timing resist or (RT) that are connected to the OSC pin. This oscillator can provide oscillating frequency in the ra nge from 20KHz to 1MHz. The waveform of the OSC pin is shown as Figure 2. Figure 2 Oscillator Waveform The cycle (T) can be determined as follows: Switching Regulator Function (1) Reference voltage circuit A temperature-compensated reference voltage (~1.25V) is generated by the reference voltage circuit from the voltage supplied by the power supply pin (pin 3). The circuit also sets the idle period besides providing the reference voltage for the switching regulator. (2) Error amplifier The error amplifier detects the output voltage of the switching regulator and sets the PWM control signal. The voltage gain is fixed. The system is made stable by connecting a phase compensation capacitor to the FB pin (pin 8). (3) PWM comparator The voltage comparator includes one inverting and three non-inverting inputs. The comparator is RTCT t VHeVX ×− = )(log VH VXRTCTt e××−= [ ]sRTCTRTCTT e ××=××−= 1.2)8.0/1.0(log

Preliminary Product Information S w i t c h i n g R e g u l a t o r C o n t r o l l e r f o r L C D B i a s Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw a voltage to pulse width converter that controls the ON time of the output pulse depending on the level of input voltage. The output level remains high when the sawtooth wave is lower than the error amplifier output voltage, the soft start setting voltage, and the idle period setting voltage. (4) Output circuit The output circuit can drive an external NPN transistor directly and has a totem pole configuration. The value of the ON/OFF current can be set by a resistor connected to the BR/CTL pin (pin 4). Stand-by mode (supply current 1µA or less) can be set by connecting the BR/CTL pin (pin4) to VCC or by making the pin open. (5) Under-Voltage Lockout (UVLO) Transients during powering on or instantaneous glitches in the supply voltage can cause the control IC to malfunction and damage the system. To prevent malfunction at low input voltage, the circuit compares the supply voltage to the internal reference voltage to detect a low input voltage. Once detected, the circuit sets the output pin low. To cancel the status, set V CC below the reset voltage V R (0.9V) and then set V CC up to the recommended operation range and the latch will be restored to operate normally.

Preliminary Product Information S w i t c h i n g R e g u l a t o r C o n t r o l l e r f o r L C D B i a s Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw Small Outline 8-pin Plastic SOL INCHES MILLIMETERSSYMBOL MIN MAX MIN MAX NOTES A 0.188 0.197 4.80 5.00 - B 0.149 0.158 3.80 4.00 - C 0.228 0.244 5.80 6.20 - D 0.050 BSC 1.27 BSC - E 0.013 0.020 0.33 0.51 - F 0.004 0.010 0.10 0.25 - H 0.053 0.069 1.35 1.75 - J 0.011 0.019 0.28 0.48 K 0.007 0.010 0.19 0.25 - M 0.016 0.050 0.40 1.27 L 0.150 REF 3.81 REF - e1 45 0 450 - α 00 80 00 80 -

Preliminary Product Information S w i t c h i n g R e g u l a t o r C o n t r o l l e r f o r L C D B i a s Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw Small Outline 8-pin TSSOP INCHES MILLIMETERSSYMBOL MIN MAX MIN MAX NOTES A 0.114 0.122 2.90 3.10 - B 0.169 0.177 4.30 4.50 - C 0.244 0.260 6.20 6.60 - D 0.026 BSC 0.65 BSC - E 0.010 0.012 0.25 0.30 - F 0.002 0.006 0.05 0.15 - H 0.041 0.047 1.05 1.20 - K 0.005 BSC 0.127 BSC - M 0.020 0.028 0.50 0.70 α 00 80 00 80 -