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RC5036
PRODUCT SPECIFICATION
9
Table1. Bill of Materials for a RC5036 RAMBUS Application
Qty.
4
1
1
1
3
Reference
C1-2, C5-6 Any
C3
C4
C7
C
IN
Manufacturer
Part Order #
Description
Requirements
and Comments
100nF, 25V Capacitor
1μF, 25V Capacitor
180pF, 50V Capacitor
10nF, 25V Capacitor
1200μF, 10V Aluminum Capacitor
Any
Any
Any
Sanyo
10MV1200GX
Rubycon
6.3ZL1500M
Any
N/A
C0G
I
RMS
= 2A , See Equation
(2) in Applications
ESR = 23m
1
C
OUT
1500μF, 6.3V Aluminum Capacitor
1
1
R1
R2
47.5
300m
PCB Trace Resistor, see
Applications
1
1
R3
R4
Any
N/A
4.75
5m
PCB Trace Resistor, 1W
PCB Trace Resistor, see
Applications
2
2
1
R5, R7
R6, R8
D1
Any
Any
Motorola
MBRB1545CT
Fairchild
FDB6030L
Fairchild
MMBT2222A
Any
Any
Fairchild
RC5036M
10K
6.65K
15A, 45V Schottky
1
Q1
30V, 14m
Logic Level MOSFET
3
Q2-4
40V, 1A NPN
Optional
1
1
L1
L2
U1
2.5μH Inductor
4.7μH Inductor
PWM Controller
I
SAT
> 8A
I
SAT
> 13A
Application Information
The RC5036 contains a precision trimmed zero TC voltage
reference, a constant-on-time architecture controller, a high
current switcher output driver, a low offset op-amp, and
switches for selecting various output modes. The block dia-
gram in Figure 2 shows how the RC5036 in combination
with the external components achieves a switchable dual
power supply.
Switch-Mode Control Loop
The main control loop for the switch-mode converter consists
of a current conditioning amplifier and one of the two voltage
conditioning amplifiers that take the raw voltage and current
information from the regulator output, compare them against
the precision reference and present the error signal to the
input of the constant-on-time oscillator. The two voltage
conditioning amplifiers act as an analog switch to select
between the internal resistor divider network (set for 3.5V)
or an external resistor divider network (adjustable for 1.5V
to 3.6V.) The switch-mode select pin determines which of
the two amplifiers is selected. The current feedback signals
come across the Iout sense resistor to the IFBH and IFBL
inputs of the RC5036. The error signals from both the cur-
rent feedback loop and the voltage feedback loop are
summed together and used to control the off-time duration of
the oscillator. The current feedback error signal is also used
as part of the RC5036 short-circuit protection.
Linear Control Loop
The low-offset op-amp is configured to be the controlling
element in a precision low-drop-out linear regulator. As can
be seen from Figure 2, the op-amp is used to compare the
divided down output of the linear regulator to the precision
reference. The error signal is used to control either an
N-channel MOSFET or a power NPN transistor.