B38C45P中文资料
BiCMOS Current Mode PWM Controller
B38C42/43/44/45
Advance Information
Pin Connection
Ordering Information
Devices Package Temp.
B38C42M SO-8 -40°C to +85°C B38C42P 8-DIP -40°C to +85°C B38C43M SO-8 -40°C to +85°C B38C43P 8-DIP -40°C to +85°C B38C44M SO-8 -40°C to +85°C B38C44P 8-DIP -40°C to +85°C B38C45M SO-8 -40°C to +85°C B38C45P 8-DIP -40°C to +85°C
Description
The Bay Linear B38C42/43/44/45 are fixed frequency and high performance current-mode PWM controller in BiCMOS. They are pin compatible with all bipolar 384X’s controllers are similar to the MIC38C4X family. These devices are designed for DC-to-DC converter applications and feature a trimmed oscillator discharge current and bandgap reference.
The benefit of the BiCMOS process provides significant performance improvement compared to Bipolar 384X devices. At 15V IN the start-up current is reduced to 50μA (typ.) from 0.17 mA with an operating current reduced to 4mA (typ.) from 14mA. Also, quicker output rise and fall times drive larger MOSFET ‘s and rail-to-rail output capability improves efficiency, especially lower supply voltages.
Major differences between members of these series are the UVLO thresholds. Typical UVLO thresholds of 14.5V (on) and 9V (off) for the B38C42 and B38C44 devices make them ideally suited to off-line applications. The corresponding typical thresholds for the B38C43 and B3845 devcies are 8.4V (on) and 7.6V (off).
The B39C4X devices are available in 8 pin DIP and SOIC. Features
?
Low-Power BiCMOS Process
? Ultra Low Start-Up Current of 50μA (typ.) ? Very Lower Operating Current (4mA) ? Current Mode Operation ≥ 500KHz ? CMOS outputs with Rail to Rail outputs ? Under Voltage Lockout with Hysteresis ? 5V Trimmed Bandgap Reference
? Trimmed Oscillator Discharged Current ? Low Cross-Conduction Currents ? Available in 8 pin SOIC and 8PDip ? Similar to MIC38C42/43/44/45
? Pin to Pin compatible with UC3842X Family
Applications
? Switched and Current Mode Power Supplies ? Off-line Power Supply
? Step-Up (Buck), Step-Down (Boost) Regulator ? Flyback, Isolated Regulators ? Synchronous FET converters ?
Forward Converters
Bay Linear
Inspire the Linear Power
B38C4X
Absolute Maximum Rating
Parameter
Symbol
Value
Unit
Supply Voltage V DD 20 V
Switch Supply Voltage V D 20 V
Output Current I OUT 1A A
Zener Current V DD 30 mA Current Sense Voltage V ISENSE -0.3 to 5.5 V Feedback Voltage V FB -0.3 to 5.5 V Power Dissipation P D 1 W Storage Temperature Range T -65 to 150 °C Lead Temperature (Soldering 10 Sec.) T L 300 °C
Electrical Characteristics
V DD = 15V (Note 4), R T = 11k, C T = 3.3nF, T A = -40°C to +85°C , unless otherwise specified Parameter Symbol Conditions MIN TYP MAX UNIT
REFERENCE SECTION
Reference Voltage V REF T J = 25 °C. I REF = 1mA 4.90 5.00 5.10 V Line Regulation REG (LINE) 12V ≤V DD ≤18V, I O = 5μA - 2 20
Load Regulation
REG (LOAD)
1mA ≤I REF ≤20mA - 1 25 mV
Short Circuit Output Current I SC T= 25 °C
-30 -80 -180 mA
OSCILLATOR SECTION Oscillator Frequency
f T= 25 °C
47 52 57 KHz Frequency Change with Voltage ?f/?V CC 12V ≤V CC ≤25V
- 0.05 1 % Oscillator Amplitude
V OSC - 1.6 2.3 V P-P
ERROR AMPLIFIER SECTION Input Bias Current I BIAS -1 -0.1 1 μA Input Voltage
V I(E>A) V 1 = 2.5V 2.42 2.50 2.58 V
Open Loop Voltage Gain G VO 2V ≤V O ≤4V
65 90 - dB Power Supply Rejection Ratio PSRR 12V ≤V CC ≤25V
60 70 - dB Output Sink Current I SINK V 2 =2.7V, V 1 = 1.1V 2 6 - mA Output Source Current I SOURCE V 2=2.3, V 1=
5V -0.5 -1.0 - mA
High Output Voltage V OH V 2=2.3, R L = 15? to GND
5 6 - V Low Output Voltage V OL V 2=2.7, R L = 15? to pin 8 - 0.8 1.1 V OUTPUT SECTION I SINK = 20mA
Low Output Voltage V OL I SINK = 200mA -
0.08 1.4 0.4
2.2
V
S ource = 20mA High Output Voltage V OH S ource = 200mA
13 12 13.5 13.0 -
- V
Rise Time t R T J = 25 °C, C L =1nF (note3) - 40 70 ns Fall Time
t F
T J = 25 °C, C L =1nF (note3)
- 30 50 ns
Note: Output Switch tests are performed under pulsed conditions to minimize power dissipation
B38C4X
Electrical Characteristics
(V CC = 15V;R T = 10?, C T = 3.3nF, T A =0 °C to +70°C , unless otherwise specified) Parameter
Symbol Conditions
MIN
TYP
MAX UNIT
CURRENT SENSE SECTION Gain G V (Note 1 & 2) 2.85 3 3.15 V/V Maximum input Signal V I(MAX) V 1 = 5V (Note 1) 0.9 1 1.1 V Power Supply Rejection
Ratio
PSRR 12V ≤V CC ≤25V
70 - dB Input Bias Current I BIAS -3 -10 μA UNDER-VOLTAGE LOCKOUT SECTION
B3842/B3844 14.5 16 17.5
Start Threshold V TH(ST)
B3843/B3845 7.8 8.4 9 V B3842/B3844 8.5 10 11.5 Min-Operating Voltage
(after Turn On) V OPR(MIN) B3843/B3845 7.0 7.6 8.2 V
PWM SECTION
B3842/B3844 Max Duty Cycle D(MAX) B3843/B3845
95 47 97 48 100
50 %
Min Duty Cycle D (MIN) - - 0 % TOTAL STANDBY CURRENT B3842A/43A/44A/45A - 100 120
Start-Up Current I ST B3842B/43B/44B/45B 100 120 μA
Operating Supply Current I CC(OPR) V 3=V 2=
ON - 14 17 mA Zener Voltage V Z I CC 30 38 - V Start-Up Current
I ST
B3842A/43A/44A/45A - 0.17 0.3 mA
PACKAGE THERMAL RESISTANCE
8-SOIC θJA 170 °C/W 8-PDip θJA 125 °C/W
This is The base
14 Pin versions
B38C4X Startup & Operating Voltage Selection Guide
UVLO Thresholds
Duty Cycle
Star-Up at 8.4V
Operating Min= 7.6V
Star-Up at 14.5V
Operating Min= 9.0V
0% to 96% B38C43 B38C42
0% to 50% B38C45 B38C44
Pin Descriptions
Pin No.# Name Function
1 COMP Output of error amplifier & input to PWM comparator
2 FB Inverting input of error amplifier
3 ISNS Current sense comparator input. It is internally limited to 1V
4 RT/CT Oscilator RC timing component connection. Resistor RT is connected to
V REF and capacitro CT is conencted to ground. Different values of RT
and CT determine the maximum duty cycle..
5 GND/PGND Combined pwoer and analog ground
6 OUT High-power, toten-pole driver output. OUT pin is activly held LOW
when V CC is below the UVLO threshold.
7 V DD Suply votlage input
8 V REF 5Volt reerence votlage output
Application Notes:
The Bay Linear B38C4X devices are compatible with generic 384x PWM devices. The following discussion highlights the differences and advantages of the Bay C design.
Start- up Current
Bau Linear BiCMOS process allows for substantial reduction in the start- up current. Typical start- up current is 95 μ A, with a maximum limit of 120 μ A. Low start- up current allows high resistance, lower- wattage, start- up resistors to supply controller start- up power.
Output Driver
The B38C4x CMOS output stage drives external power MOSFETs to the full supply voltage. Low ON- resistance and high peak current drive combine to give greater than 1000pF gate capacitance drive capability. Rise and fall time requirements may dictate the appropriate value of output capacitance. Within the restrictions of output capacity and controller power dissipation, switching frequencies can exceed 1MHz.
The CMOS output stage “ break- before- make” action is guaranteed by design and insures that no cross- conduction current will flow. This minimizes heat dissipation, increases efficiency and enhances reliability.
Oscilator Operation
Two external components, RT and CT, set the switching frequency.
With VCC = 14V, RT = 10k and CT = 3.3nF, nominal switching frequency is 50kHz.
B38C4X
Advance Information- These data sheets contain descriptions of products that are in development. The specifications are based on the engineering calculations, computer simulations and/ or initial prototype evaluation.
Preliminary Information- These data sheets contain minimum and maximum specifications that are based on the initial device characterizations. These limits are subject to change upon the completion of the full characterization over the specified temperature and supply voltage ranges.
The application circuit examples are only to explain the representative applications of the devices and are not intended to guarantee any circuit design or permit any industrial property right to other rights to execute. Bay Linear takes no responsibility for any problems related to any industrial property right resulting from the use of the contents shown in the data book. Typical parameters can and do vary in different applications. Customer’s technical experts must validate all operating parameters including “ Typical” for each customer application.
LIFE SUPPORT AND NUCLEAR POLICY
Bay Linear products are not authorized for and should not be used within life support systems which are intended for surgical implants into the body to support or sustain life, in aircraft, space equipment, submarine, or nuclear facility applications without the specific written consent of Bay Linear President.