L2800

L2800 UTC | Alldatasheet

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UTC L2800 LINEAR INTEGRATED CIRCUIT UTC UNISONIC TECHNOLOGIES CO., LTD. 1 QW-R121-010,A SWITCHING REGULATOR CONTROLLER(LOW VOLTAGE)

DESCRIPTION

The UTC L2800 is a single-channel switching regulator control IC for low voltage applications incorporating a soft start function and short circuit detection function. The device has a low minimum operating voltage of 1.8V and is ideal for the power supply of battery-operated electronic equipment.

FEATURES

*Wide supply voltage operating range: 1.8V~15V *Low current consumption: Typically 5.5mA in operation,1µA or less in stand-by *High speed operation is possible: Maximum 1MHz *The error amplifier gain is set inside the IC,so peripheral components are minimized. *Incorporates a soft start circuit. *Incorporates a timer-latch type short circuit detection circuit (SCP). *Totem-pole type output with adjustable on/off current (for NPN transistors) *Incorporates a stand-by function. SOP-8 TSSOP-8 PIN CONFIGURATION -IN 1 SCP Vcc 5BR/CTL FB OSC GND OUT

UTC L2800 LINEAR INTEGRATED CIRCUIT UTC UNISONIC TECHNOLOGIES CO., LTD. 2 QW-R121-010,A PIN DESCRIPTION PIN NO. SYMBOL I/O DESCRIPTION 1 -IN I Error amplifier inverting input pin

2 SCP - Soft start and SCP setting capacitor connection pin

3 VCC - Power supply pin

4 BR/CTL I Output current setting and control pin

5 OUT O Totem-pole type output pin

6 GND - Ground pin

7 OSC - Capacitor and resistor connection pin for setting the oscillation frequency

8 FB O Error amplifier output pin

500Ω 36kΩ 3 7 6 2 4 Reference voltage supply Sawtooth wave oscillator Output drive control circuit Soft start SCP 30kΩ BR/CTLSCPGND FB -IN Vcc OSC OUT 0.3VDTC 0.6V PWM Comp. 0.1V 0.5V Error Amp. 1.25V 0.6V 0.1V ABSOLUTE MAXIMUM RATINGS (Ta=25℃) PARAMETER SYMBOL RATINGS UNIT Power Supply Voltage Vcc 16 V Output Source Current I O+ -50 mA Output Sink Current I O- 50 mA Power Dissipation SOP-8 TSSOP-8 P D 570* 580* mW Storage Temperature Tstg -55 ~ +125 °C Operating Temperature Top -30 ~ +85 °C * When mounted on a 10cm square double-sided epoxy board.

UTC L2800 LINEAR INTEGRATED CIRCUIT UTC UNISONIC TECHNOLOGIES CO., LTD. 3 QW-R121-010,A RECOMMENDED OPERATING CONDITIONS (Ta=25°C) PARAMETER SYMBOL MIN TYP MAX UNIT Power Supply Voltage Vcc 1.8 15 V Error Amplifier Input Voltage V I -0.2 1.0 V BR/CTL Pin Input Voltage V BR -0.2 Vcc V Output Source Current I O+ -40 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 fosc 10 500 1000 kHz Operating Temperature Top -30 +25 +85 °C

ELECTRICAL CHARACTERISTICS

(Ta=25°C, VCC=+2V) PARAMETER SYMBOL TEST CONDITIONS MIN TYP MAX UNIT Reset Voltage V R 0.9 V Circuit to prevent malfuncition at low input oltage (U.V.L.O) Threshold Voltage V TH 1.1 1.3 1.5 V Charging Current Ics V SCP=0V -1.5 -1.0 -0.7 µA Soft Start Voltage at soft start completion Vts 0.7 0.8 0.9 V Charging Current Icpc V SCP=0V -1.5 -1.0 -0.7 µA Short Circuit Oscillation Frequency fosc RT=3.0kΩ, CT=270pF 400 500 600 kHz Frequency Input Stability fdV Vcc=2V ~ 15V 2 10 % Sawtooth Wave Oscillator(OSC) Frequency Variation With Temperature fdT Ta=-30°C ~ +85°C 5 % Input Threshold Voltage V T V FB=450mV 480 500 520 mV VT Input Stability V TdV Vcc=2V ~ 15V 5 20 mV VT Variation With Temperature VTdT Ta=-30°C ~ +85°C 1 % Input Bias Current I B V IN=0V -1.0 -0.2 1.0 µA Voltage Gain Av 70 100 145 V/V Frequency Bandwidth BW A V=0dB 6 MHz VOM+ 0.78 0.87 V Maximum 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=0.45V 24 40 µA Idle Period Adjustment Section Maximum Duty Cycle t DUTY RT=3.0kΩ, CT=270pF VFB=0.8V 65 75 85 % VOH1 RB=390Ω, Io=-15mA 1.0 1.2 V VOH2 RB=750Ω, Vcc=1.8V Io= -10mA 0.8 1.0 V VOL1 RB=390Ω, Io=15mA 0.1 0.2 V Output Voltage VOL2 RB=750Ω, Vcc=1.8V Io=10mA 0.1 0.2 V Output Source Current I O+ RB=390Ω, Vo=0.9V -30 -20 mA Output Sink Current I O- RB=390Ω, Vo=0.3V 30 60 mA Output Section Pull Down Resistance R O 20 30 40 kΩ

UTC L2800 LINEAR INTEGRATED CIRCUIT UTC UNISONIC TECHNOLOGIES CO., LTD. 4 QW-R121-010,A PARAMETER SYMBOL TEST CONDITIONS MIN TYP MAX UNIT Pin Voltage V BR RB=390Ω 0.2 0.3 0.4 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=390Ω 5.5 9.3 mA DIAGRAM FB pin voltage Reference input for short circuit detection comparator Idle period setting voltage Soft start setting voltage Sawtooth wave output OUT pin waveforms SCP pin waveforms OFF ON Power supply control SW Soft start ts Output short circuit tPE Output short circuit Short circuit detection HOW TO SET THE TIME CONSTANT FOR SOFT START AND SHORT CIRCUIT DETECTION 1.SOFT START At power on, the capacitor CPE connected to the SCP pin starts charging. The PWM comparator compares the soft start setting voltage as a proportion of the voltage at the SCP pin with the sawtooth waveform. The comparison controls the ON duty of the OUT pin, causing the soft start operation. On completion of soft start operation, the voltage at the SCP pin stays low, the soft start setting voltage stays high, and the circuit enters the output short circuit detection wait state. Soft start time (The time until the output ON duty reaches approximately 50%) ts[S]≒0.35*C PE[µF] 2.SHORT CIRCUIT PROTECTION If the switching regulator output suddenly drops due to load effect, the error amplifier output (FB pin) is fixed at VOM+ and capacitor CPE starts charging. When the voltage at the SCP pin reaches approximately 0.8V,the output pin is set low and the SCP pin stays low. Once the protection circuit operates, the circuit can be restored by resetting the power supply.

• Short circuit detection time tPE[S]≒0.8*CPE[µF]

UTC L2800 LINEAR INTEGRATED CIRCUIT UTC UNISONIC TECHNOLOGIES CO., LTD. 5 QW-R121-010,A TYPICAL CHARACTERISTICS Supply Voltage vs.Supply Current 81 2 16 20 Supply voltage ,Vcc ( V ) Supply current ,Icc (mA) -40 -10 -20 -15 20 40 60 80 100 Supply Voltage vs.Input Threshold Voltage 0.2 0.4 0.6 81 2 1 6 20 0.8 1.0 Supply voltage ,Vcc ( V ) Supply Voltage vs.Input Threshold Voltage 0.2 0.4 0.6 1.0 2.0 3.0 4.0 5.0 0.8 1.0 Supply voltage ,Vcc ( V ) Ambient Temperature vs. Input Threshold Voltage Variation Ratio High Level Output 0.4 0.8 1.2 -100 -20 -30 -40 -50 1.6 2.0 Low Level Output 100 200 300 40 60 80 100 400 500 Low level output voltage ,V OUT (mV) Input threshold Voltage ,V T (V) Input threshold voltage ,V T (V) Ambient temperature ,Ta ( ℃) High level output current ,I OUT(mA) Ta=+25℃ RB=390Ω Ta=+25℃ Ta=+25℃ Vcc=2V Vcc=2V Ta=+25℃ RB=390Ω Vcc=2V Ta=+25℃ RB=390Ω Input threshold voltage variation ration ,ΔVT/VT (%) High level output current ,I OUT(mA) Low level output voltage ,V OUT (V)

UTC L2800 LINEAR INTEGRATED CIRCUIT UTC UNISONIC TECHNOLOGIES CO., LTD. 6 QW-R121-010,A BR/CTL Pin Current vs. Output Source Current -10 -20 -30 -0.4 -40 -50 20k 50k 10k 2k 5k 10k 500k Oscillation frequency ,fosc (Hz) 100 200 300 -0.4 400 500 1.0 2.0 3.0 -20 -40 -60 -80 -100 4.0 5.0 Timing Resistor vs. Oscillation Frequency Supply Voltage vs. Frequency Variation Ratio -15 02 46 8 -10 Supply voltage ,Vcc (V) Frequency variation ratio ,Δf/f (%) BR/CTL Pin Current vs. BR/CTL Pin Voltage BR/CTL Pin Current vs. Supply Current 20k Timing resistor ,R T (Ω) -40 -10 -20 -15 20 40 60 80 Ambient Temperature vs. Frequency Variation Ratio 100 BR/CTL pin Current ,I BR (mA) Output source current ,I OUT (mA) BR/CTL pin current ,I BR (mA) BR/CTL pin voltage ,VBR (mV) Supply current ,I CC (mA) 200k 100k 10 12 14 16 Vcc=2V CT=270pF RT=3.0kΩ Ambient temperature ,Ta (℃) Frequency variation ratio ,Δf/f (%) Vcc=2V VOUT=0.9V Ta=+25℃ Vcc=2V Ta=+25℃ Vcc=2V Ta=+25℃ Vcc=2V Ta=+25℃CT=100pF CT=1000pF CT=10000pF CT=270pF Ta=+25℃ RT=3.0kΩ BR/CTL pin current ,I BR (μA)

UTC L2800 LINEAR INTEGRATED CIRCUIT UTC UNISONIC TECHNOLOGIES CO., LTD. 7 QW-R121-010,A Oscillation Frequency vs.Maximum Duty Cycle 10K 0 100K 1M 100 Oscillation frequency ,fosc (Hz) Maximum duty cycle, tDUTY (%) Vcc=2V CT=270pF Ta=+25℃ -50 Note:The OFF delay time of VOUT depends on the characteristics of the external transistor. Output Pin Voltage and Current Waveforms (Reference Data) (V) VOUT (mA) IOUT 10mV 200ns Vcc=2V CT=270pF RT=1.0kΩ t (μs) Measurement Circuit Diagram -IN Vcc VOUT 390Ω IOUT 18kΩ (5V) UTC L2800 22μH 10μF 2kΩ

UTC L2800 LINEAR INTEGRATED CIRCUIT UTC UNISONIC TECHNOLOGIES CO., LTD. 8 QW-R121-010,A FUNCTIONAL DESCRIPTION 1. SWITCHING REGULATOR FUNCTION (1) REFERENCE VOLTAGE CIRCUIT The reference voltage circuit generates a temperature-compensated reference voltage( ≒1.25V)from voltage supplied from the power supply pin(pin 30).In addition to providing the reference voltage for the switching regulator, the circuit also sets the idle period. (2) SAWTOOTH WAVE OSCILLATOR The sawtooth oscillator generates a sawtooth wave(up to 1 MHz)that is stable with respect to the supply voltage and temperature. The capacitor and resistor t hat set the oscillation frequency are connected to the OSC pin(pin 7). (3) ERROR AMPLIFIER (ERROR AMP.) The error amplifier detects the output voltage of the switching regulator and outputs the PWM control signal. The voltage gain is fixed, and connecting a phase compensat ion capacitor to the FB pin(pin 8)provides stable phase compensation for the system. (4) PWM COMPARATOR (PWM COMP.) The voltage comparator has one inverting and three non-in verting inputs. The comparator is a voltage /pulse width converter that controls the ON time of the output pulse depending on the input voltage. The output level is high(H) when the sawtooth wave is lower than the error amplifier output voltage, soft start setting voltage, and idle period setting voltage. (5) OUTPUT CIRCUIT The output circuit has a totem pole type configuration and can drive an external NPN transistor directly. The value of the ON/OFF current can be set by a resistor connected to the BR/CTL pin(pin 4). 2. POWER SUPPLY CONTROL FUNCTION Stand-by mode(supply current 1µA or less) can be set by connecting the BR/CTL pin(pin 4) to Vcc or by making the pin open circuit. SW MODE OFF Stand-by mode ON Operating mode RB SW BR/CTL UTC L2800 3. OTHER FUNCTIONS (1) SOFT START AND SHORT CIRCUIT DETECTION Soft start operation is set by connecting capacitor CPE to SCP pin(pin 2).Soft start prevents a current spike on start-up. On completion of soft start operation, the SCP pin(pin 2) stays low and enters the short circuit detection wait state. When an output short circuit occurs, the error amplifier output is fixed at V OM+ and capacitor C PE starts charging. After charging to approximately 0.8V,the output pin(pin 5) is set low and the SCP pin(pin 2) stays low. Once the protection circuit operates, the circuit can be restored by resetting the power supply.(See “HOW TO SET THE TIME CONSTANT FOR SOFT START AND SHORT CIRCUIT DETECTION”)

UTC L2800 LINEAR INTEGRATED CIRCUIT UTC UNISONIC TECHNOLOGIES CO., LTD. 9 QW-R121-010,A (2) CIRCUIT TO PREVENT MALFUNCTION AT LOW INPUT VOLTAGE Transients when powering on or instantaneous glitches in the supply voltage can lead to malfunction of the control IC and cause system damage or failure. The circuit to prevent malfunction at low input voltage detects a low input voltage by comparing the supply voltage to the internal reference voltage. On detection, the circuit fixes the output pin to low. The system recovers when the supply voltage rises back above the threshold voltage of the malfunction prevention circuit. APPLICATION EXAMPLE 18kΩ BR/CTL SCP GND FB-IN Vcc OSC OUT VO 22μH 10μF 0.1μF3kΩ270pF 390Ω0.1μF2kΩ 33μF VIN CTL UTC assumes no responsibility for equipment failures that result from using products at values that exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or other parameters) listed in products specifications of any and all UTC products described or contained herein. UTC products are not designed for use in life support appliances, devices or systems where malfunction of these products can be reasonably expected to result in personal injury. Reproduction in whole or in part is prohibited without the prior written consent of the copyright owner. The information presented in this document does not form part of any quotation or contract, is believed to be accurate and reliable and may be changed without notice.