GM38C42S8R

GM38C42 GAMMA | Alldatasheet

Document overview

• Manufacturer or author: Provided By ALLDATASHEET.COM(FREE DATASHEET DOWNLOAD SITE)
• PDF pages: 11

Technical content

Features

40ns output rise and 30ns output fall times -40° to +85°C temp. range same as standard UC284x Low-power BiCMOS Process Very low start-up current (50µA typical) Low operating current (4mA typical) CMOS outputs with rail-to-rail swing 500kHz current-mode operation Pin-for-pin compatible with UC3842/ 3843 / 3844/ 3845(A) Trimmed oscillator discharge current UVLO with hysteresis Low cross-conduction currents GM38C42, GM38C43, GM38C44, GM38C45 www.gammamicro.com 1 Step-up "boost" regulators Flyback, isolated regulators Forward converters Synchronous FET converters V0.1

MARKING INFORMATION & PIN CONFIGURATIONS (TOP VIEW) A = Assembly Location Y = Year W W = Weekly Ordering Number Package Shipping GM38C42S8T GM38C43S8T GM38C44S8T GM38C45S8T GM38C42S8R GM38C43S8R GM38C44S8R GM38C45S8R GM38C42D8T GM38C43D8T GM38C44D8T GM38C45D8T SOP - 8 SOP - 8 SOP - 8 SOP - 8 SOP - 8 SOP - 8 SOP - 8 SOP - 8 DIP-8 DIP-8 DIP-8 DIP-8

100 Units/ Tube

2,500 Units/ Tape & Reel 2,500 Units/ Tape & Reel 2,500 Units/ Tape & Reel 2,500 Units/ Tape & Reel

60 Units/ Tube

GM38C42, GM38C43, GM38C44, GM38C45

ORDERING INFORMATION

• For detail Ordering Number identification, please see last page. DIP - 8 2 3 4 5678 COMP FB GM38CXX AYWW SOP - 8 2 3 4 5678 COMP FB GM38CXX AYWW VDD VREF OUT GND R / CTT ISNS

COMP Compensation: Connect external Compensation network to modify the error amplifier output. PIN LEAD FB Feedback (Input): Error amplifier input .Feedback is 2.5Vat desired output voltage.2 ISNS Current Sense (Input): Current sense comparator input. Connect to current sensing resistor or current transformer.3 R / CTT Timing Resistor / Timing Capacitor: Connect external RC network to select switching frequency.4

5 GND

Ground: Combined analog and power ground. Power Output: Totem - pole output.6 VDD Analog Supply (Input): Controller circuitry supply input. Return to analog ground (AGND). 5V Reference (Output): Connect external RC network.VREF BLOCK DIAGRAM GM38C42, GM38C43, GM38C44, GM38C45 PARAMETER SYMBOL VALUE UNIT 30 mAIDD ABSOLUTE MAXIMUM RATINGS Supply Voltage(Note 6) Switch Supply Voltage Current Sense Voltage Feedback Voltage Output Current Storage Temperature - 0.3 to + 5.5 0.5 V V V V A VDD VD VISNS VFB IOUT TA - 0.3 to + 5.5 - 50 to + 150 Zener Current Operation at 16V may require special precautions(Note6) V DD V REF R / CTT FB 35V OUTPUT Reference UVLO Oscillator 2.5V R S R Q QT COMP GND* ISNS * 8 - lead versions only PARAMETER SYMBOL VALUE UNIT 150TJ OPERATING RATINGS Junction Temperature °C

GM38C42, GM38C43, GM38C44, GM38C45

ELECTRICAL CHARACTERISTICS

(T = -40°C to 85 , Note 4, V = 15V, C =3.3 nF, R =10kW, unless otherwise noted )A DD T T°C CHARACTERISTICS TEST CONDITIONS MIN TYP MAX UNIT Output Voltage Line Regulation Reference Section T = 25°C, I = 1mAAO 4.9 5.0 V mV 5.1 2012V V 16V, I = 5µA, (Note 6)DD O Load Regulation 1 mV251 I 20mAO Temp. Stability 0.2 mV / °C(Note 1) Total Output Variation Line, Load, Temp.,Note 1 4.82 5.18 V Output Noise Voltage 50 µV10Hz f 10kHz, T = 25°C, (Note 1)A Long Term Stability 5 mVT = 125°C, 1000hrs., (Note 1)A 25 Output Short Circuit -80 mA-180-30 Oscillator Section Initial Accuracy 52 KHz5549T = 25°C, (Note 5)A Voltage Stability 0.2 %1.012 V 16V, (Note 6)DD Temp. Stability 0.04 % / °CT T T , (Note 1)MIN A MAX Clock Ramp Reset Current T T TMIN A MAX T = 25°C, V = 2V,A RT/CT 7.7 7.2 8.4 8.4 9.0 9.5 mA Amplitude 1.9 Vp-pV (Peak to Peak)RT/CT Error Amplifier Section Input Current -0.1 µAV = 5VFB -2 Input Voltage 2.5 VV = 2.5VCOMP 2.582.42 Open Loop Voltage Gain dB652V V 4VO Power Supply Rejection Ratio 6012V V 16VDD dB Output Sink Current 142V = 2.7V, V = 1.1VFB COMP mA Output Source Current -1-0.5V = 2.3V, V = 5VFB COMP mA High Output Voltage 6.65.0V = 2.3V, R = 15k to GNDFB L V Low Output Voltage 0.1V = 2.7V, R = 15k to VFB L REF V1.1 1.0(Note 1) MHz Current Sense Section Gain Note 2 and 3 Maximum Threshold 1.0 VV = 5V, (Note 2)COMP 1.1 2.85 PSRR 70 dB 0.9 Input Bias Current -1.0 12V V 16V, (Note 2)DD Delay to Output 120 µA-2 250 ns 0.7 3.0 3.15 V / V Unity Gain Bandwidth

GM38C42, GM38C43, GM38C44, GM38C45 (T = -40°C to 85°C, Note 4, V = 15V, C =3.3 nF, R =11kW, unless otherwise noted )A DD T T TEST CONDITIONS TYP MAX UNIT CHARACTERISTICS TEST CONDITIONS MIN Output Section Undervoltage Lockout Section PWM Section Total Standby Current R HighDS(ON) R LowDS(ON) Start Threshold Maximum Duty Cycle Start - Up Current Minimum Operating Voltage Rise Time Fall Time I = 200mASOURCE GM38C42, GM38C44 V = 13V for GM38C42, GM38C44DD V = 7.5V for GM38C43, GM38C45DD I = 200mASINK T = 25°C, C = 1nFAL T = 25°C, C = 1nFAL 14.5 8.4 7.6 W µA ns ns Minimum Duty Cycle Operating Supply Current Zener Voltage (V )DD V = V = 0VFB ISNS I = 25 mA, Note 6DD mA V GM38C43, GM38C45 GM38C42, GM38C44 GM38C43, GM38C45 13.5 7.8 7.0 15.5 9.0 8.2 V V GM38C42, GM38C43 GM38C44, GM38C45 200 Note 1: These parameters, although guaranteed, are not 100% tested in production. Note 2: Parameter measured at trip point of latch with V = 0.EA Note 3: Gain defined as: A = ; 0 V (I ) 0.8VTH SNS Note 4: Adjust V above the start threshold before setting at 15V.DD Note 5: Output frequency equals oscillator frequency for the GM38C42 and GM38C43. Output frequency for the GM38C44, and GM38C45 equals one half the oscillator frequency. Note 6: On 8-pin version, 18V is maximum input on pin 7, as this is also the supply pin for the output stage. DVPIN1 V (I ) TH SNS

GM38C42, GM38C43, GM38C44, GM38C45

Application Information

Familiarity with 384x converter designs is assumed. GM38C4x has been designed to be compatible with 384xA series controllers. GM38C4x Advantages Start-up Current Start-up current has been reduced to an ultra-low 50µA(typical) permitting higher-valued, lower-wattage, and start-up resistors (power controller during power supply start-up). The reduced resistor wattage reduces cost and printed circuit space. Operating Current Operating current has been reduced to 4mA compared to 11mA for a typical bipolar controller. The controller runs cooler and the V hold-up capacitance required during start-up may be reduced.DD Output Driver Complementary internal P-and N-channel MOSFET s produce rail-to-rail output voltages for better performance driving external power MOSFETs. The driver transistor's low on resistance and high peak current capability can drive gate capacitances of greater than 1000pF . The value of output capacitance which can be driven is determined only by the rise/fall time requirements. Within the restrictions of output capacity and controller power dissipation, maximum switching frequency can approach 500kHz. Design Precautions When operating near 20V, circuit transients can easily exceed 20V absolute maximum rating and permanently damaging the controller's CMOS construction. T o reduce transients, use a 0.1µF low-ESR capacitor to next to the controller's supply V (or V for '-1' versions)and ground connections. DD D Film type capacitors, such as Wima MKS2, are recommended. When designing high -frequency converters, avoid capacitive and inductive coupling of the switching waveform into high impedance circuitry such as the error amplifier, oscillator , and current sense amplifier. Avoid long printed-circuit traces and component leads. Locate oscillator and compensation circuitry neat the IC. Use high frequency decoupling capacitors on V , and if necessary, on V . Return high di/dt currents directly to their ERF DD source and use large ground planes. Buck Converter Refer to Figure 7. When at lest 26V is applied to the input, C5 is charged through R2 until the voltage V is DD greater than 14.5V(the undervoltage lockout value of the GM38C42), output switching begins when Q1is turned on by the gate drive transformer T1 and charging the output filter capacitor C3 through L1. D5 supplies a regulated +12V to V once the circuit is running. DD Current sense transformer CT1 provides current feedback to ISNS for current-mode operation and cycle-by-cycle current limiting. This is more efficient than a high- power sense resistor and provides the required ground- referenced level shift. When Q1 turns off, current flow continues from ground through D1 and L1 until Q1 is turned on again. The 100V Schottky diode D1 reduces the forward voltage drop in the main current path, resulting in higher efficiency than could be accomplished by using an ultra-fast recovery diode. R1 and C2 suppress parasitic oscillations from D1. Using a high-value inductance for L1 and a low-ESR capacitor for C3 permits small capacitance with minimum output ripple. This inductance value also improves circuit efficiency by reducing the flux swing in L1. Magnetic components are carefully chosen for minimal loss at 500kHz.

Figure 7. 500kHz, 25W, Buck Converter

GM38C42, GM38C43, GM38C44, GM38C45 0.275 7.0 0.155 4.0 0.060 1.52 0.050 1.270 0.024 0.6 Inches mm( ) Pad Layout SOP-8 P ACKAGE OUTLINE DIMENSIONS 0.236 ± 0.008

0.050 NOM

1.270 NOM

+0.21 -0.205.990 3.91 ± 0.1 +0.003 -0.0040.154 PIN INDENT 1.600 ± 0.130 0.063 ± 0.005

0.057 NOM

1.450 NOM

0.175 ± 0.075 0.007 ± 0.003 +0.004 -0.0030.016 +0.10 -0.080.410 +0.0018 -0.00050.008 +0.05 -0.010.200 +0.013 -0.0220.028 +0.33 -0.560.710 +0.002 -0.0040.191 +0.05 -0.104.850 Inches mm( ) 0 ~ 8°° DIP-8 P ACKAGE OUTLINE DIMENSIONS

0.015 MIN

0.380 MIN

0.26 ± 0.006 +0.15 -0.166.60 0.36 ± 0.01 +0.25 -0.269.14

0.180 MAX

4.570 MAX

0.125 MIN

3.180 MIN

+0.002 -0.0060.13 +0.05 -0.153.30 0.018 ± 0.004 0.46 ± 0.10 0.039 ± 0.07 0.99 ± 0.18 0.06 ± 0.01 +0.26 -0.251.52

0.100 NOM

2.540 NOM

0.021 ± 0.005 +0.12 -0.130.53 +0.010 -0.0150.30 +0.25 -0.387.62 +0.002 -0.0030.01 +0.05 -0.080.25 0.365 ± 0.02 9.27 ± 0.51 Inches mm( )

GM38C42, GM38C43, GM38C44, GM38C45 ORDERING NUMBER GM 38 4X C S8 R Gamma Micro. Circuit Type BiCOMS Process Package S8: SOP-8 D8: DIP-8 Shipping T: Tube R: Tape & Reel

GM38C42, GM38C43, GM38C44, GM38C45