MC33341D ON Semiconductor, MC33341D Datasheet - Page 6

• Manufacturer Part Number: MC33341D
• Description: IC CTRLR BATTERY PS REG 8-SOIC
• Manufacturer: ON Semiconductor

Specifications of MC33341D

• Function: Charge Management
• Battery Type: All Battery Types
• Voltage - Supply: 2.3 V ~ 16 V
• Operating Temperature: -25°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (0.154", 3.90mm Width)
• Output Current: 50 mA
• Operating Supply Voltage: 2.3 V to 15 V
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 25 C
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

INTRODUCTION
control of output voltage and current in order to prevent
catastrophic damage to the system load. Many present day
power sources contain a wide assortment of building blocks
and glue devices to perform the required sensing for proper
regulation. Typical feedback loop circuits may consist of a
voltage and current amplifier, level shifting circuitry,
summing circuitry and a reference. The MC33341 contains
all of these basic functions in a manner that is easily
adaptable to many of the various power source−load
configurations.
OPERATING DESCRIPTION
is specifically designed to simultaneously close the voltage
and current feedback loops in power supply and battery
charger applications. This device can control the feedback
loop in either constant−voltage or constant−current mode
with automatic crossover. A concise description of the
integrated circuit blocks is given below. Refer to the block
diagram in Figure 14.
Transconductance Amplifier
the feedback loop. This amplifier has separate voltage and
current channels, each with a sense and a threshold input.
Within a given channel, if the sense input level exceeds that
of the threshold input, the amplifier output is driven high.
The channel with the largest difference between the sense
and threshold inputs will set the output source current of the
amplifier and thus dominate control of the feedback loop.
The amplifier output appears at Pin 8 and is a source−only
type that is capable of 15 mA.
amplifier is made available at Pin 3 for loop compensation.
This pin can sink and source up to 10 mA of current. System
stability is achieved by connecting a capacitor from Pin 3 to
ground. The Compensation Pin signal is out of phase with
respect to the Drive Output. By actively clamping Pin 3 low,
the Drive Output is forced into a high state. This, in effect,
will shutdown the power supply or battery charger, by
forcing the output voltage and current regulation threshold
down towards zero.
Voltage Sensing
the noninverting V
amplifier. This voltage is resistively scaled down and
connected to Pin 5. The threshold at which voltage
regulation occurs is set by the level present at the inverting
V
controlled by Pin 6. In source high−side and load high−side
current sensing modes, Pin 6 must be connected to the low
potential side of current sense resistor R
conditions, the voltage regulation threshold is internally
fixed at 1.2 V. In source return low−side and load low−side
th
Power supplies and battery chargers require precise
The MC33341 is an analog regulation control circuit that
A quad input transconductance amplifier is used to control
A high impedance node within the transconductance
The voltage that appears across the load is monitored by
input of the transconductance amplifier. This level is
sen
input of the transconductance
S
. Under these
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MC33341
6
current sensing modes, Pin 6 is available, and can be used to
lower the regulation threshold of Pin 5. This threshold can
be externally adjusted over a range of 0 V to 1.2 V with
respect to the IC ground at Pin 4.
Current Sensing
voltage that appears across sense resistor R
it with respect to Pin 4 if required, and applying it to the
noninverting I
order to allow for maximum circuit flexibility, there are
three methods of current sensing, each with different
internal paths.
high−side (Figures 18 and 19) current sensing, the
Differential Amplifier is active with a gain of 1.0. Pin 1
connects to the high potential side of current sense resistor
R
provided to disable the Differential Amplifier output
whenever low−side current sensing is required. This circuit
clamps the Differential Amplifier output high which
disconnects it from the I
Amplifier. This happens if Pin 1 is less than 1.2 V or if Pin 1
is less than Pin 6.
and 17), the Inverting Amplifier is active with a gain of −1.0.
Pin 1 connects to the low potential side of current sense
resistor R
a negative voltage appears across R
Noninverting input path is active with a gain of 1.0. Pin 1
connects to the high potential side of current sense resistor
R
input path lies from Pin 1, through the Inverting Amplifier
input and feedback resistors R, to the cathode of the output
diode. With load low−side current sensing, Pin 1 will be
more positive than Pin 4, forcing the Inverting Amplifier
output low. This causes the diode to be reverse biased, thus
preventing the output stage of the amplifier from loading the
input signal that is flowing through the feedback resistors.
modes is internally fixed at 200 mV with Pin 2 connected to
V
over a range of 0 to 200 mV with respect to the IC ground
at Pin 4.
Reference
voltage threshold and 200 mV current threshold. The
reference is initially trimmed to a ±1.0% tolerance at
T
ambient operating temperature range of −25° to 85°C.
Applications
this device. The circuits shown in Figures 14 through 21
contain an optoisolator connected from the Drive Output at
A
S
S
CC
Current sensing is accomplished by monitoring the
In source high−side (Figures 14 and 15) and load
With source return low−side current sensing (Figures 16
In load low−side current sensing (Figures 20 and 21) a
The regulation threshold in all of the current sensing
An internal band gap reference is used to set the 1.2 V
Each of the application circuits illustrate the flexibility of
while Pin 6 connects to the low side. Logic circuitry is
while Pin 4 connects to the low side. The Noninverting
= 25°C and is guaranteed to be within ±2.0% over an
. Pin 2 can be used to externally adjust the threshold
S
while Pin 4 connects to the high side. Note that
sen
input of the transconductance amplifier. In
sen
input of the Transconductance
S
with respect to Pin 4.
S,
level shifting