rc5037 Fairchild Semiconductor, rc5037 Datasheet - Page 6

• Manufacturer Part Number: rc5037
• Description: Adjustable Switching Regulator Controller
• Manufacturer: Fairchild Semiconductor

RC5037
Table1. Bill of Materials for a RC5037 3.3V, 13A Application
Application Information
The RC5037 contains a precision trimmed zero TC voltage
reference, a constant-on-time architecture controller, a high
current output driver, and a low offset error amp. The
detailed block diagram in Figure 1 shows how the RC5037
works together with external components to achieve a high-
performance switching power supply.
Switch-Mode Control Loop
The main control loop for the switch-mode converter consists
of a current conditioning amplifier and a voltage conditioning
amplifier. The voltage amplifier compares the voltage from the
internal reference with the converter’s output voltage divided
by an external resistor divider. The current amplifier senses the
current by comparing the voltages at the IFBH and IFBL pins,
which are attached to either side of the current sense resistor.
The signals from the voltage and current amplifiers are
summed together, the result being used to control the off-time
of the oscillator. The current feedback signal is also used as
part of the RC5037 short-circuit protection.
6
Optional L1
Qty.
3
3
1
1
6
1
1
1
1
1
1
1
1
1
1
1
Reference
C1, C7-8
C2-4
C5
C6
C9-14
R1
R2
R3
R4
R5
D1
D2
D3
Q1
L2
U1
Sanyo
10MV1200GX
Any
Any
Sanyo
6MV1500GX
Any
Any
N/A
Any
Any
Motorola
MBRB1545CT
Fairchild
MMBD4148
Motorola
1N4735A
Fairchild
FDB6030L
Any
Any
Fairchild
RC5037M
Any
Manufacturer
Part Order #
100nF, 25V Capacitor
1200µF, 10V Aluminum Capacitor
1µF, 25V Capacitor
180pF, 50V Capacitor
1500µF, 6.3V Aluminum Capacitor
47.5
4.75
5.2m , 1W Resistor
2.43K
2K
15A, 45V Schottky
Signal Diode
6.2V Zener
30V, 14m Logic Level MOSFET
2.5µH Inductor
4.7µH Inductor
PWM Controller
Description
High Current Output Drivers
The RC5037 high current output driver (DRV) contains high
speed bipolar power transistors configured in a push-pull
configuration. The output driver is capable of supplying 0.5A
of current in less than 100ns. The driver’s power and ground
are separated from the overall chip power and ground for
added switching noise immunity.
Internal Reference
The reference in the RC5037 is a precision band-gap type
reference. Its temperature coefficient is trimmed to provide a
near zero TC.
Constant-On-Time Oscillator
The RC5037 switch-mode oscillator is designed as a fixed
on-time, variable off-time oscillator. The constant-on-time
oscillator consists of a comparator, an external capacitor, a
fixed current source, a variable current source, and an analog
switch that selects between two threshold voltages for the
comparator. The external timing capacitor is alternately
I
(2) in Applications
C0G
ESR = 44m
PCB Trace Resistor, see
Eauation (3) Applications
I
I
RMS
SAT
SAT
PRODUCT SPECIFICATION
> 8A
> 13A
and Comments
= 2A , See Equation
Requirements