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MC33341D

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P19
MC33341
http://onsemi.com
4
0
0
0
0
−50
1.0
0
280
0
1.6
−50
4.0
V
Pin
2
, CURRENT THRESHOLD ADJUST (mV)
V
Pin
2
, CURRENT THRESHOLD ADJUST (V)
T
A
, AMBIENT TEMPERATURE (°C)
V
Pin
2
, CURRENT THRESHOLD ADJUST (mV)
V
Pin
6
, VOLTAGE THRESHOLD ADJUST (V)
Figure 2. Voltage Sensing
Threshold Change versus Temperature
T
A
, AMBIENT TEMPERATURE (°C)
Figure 3. Current Sensing
Threshold Change versus Temperature
V
CC
= 6.0 V
Figure 4. Closed−Loop Voltage Sensing Input
versus Voltage Threshold Adjust
Figure 5. Closed−Loop Current Sense Input B
versus Current Threshold Adjust
Figure 6. Closed−Loop Current Sensing Input A
versus Current Threshold Adjust
Figure 7. Closed−Loop Current Sensing Input A
versus Current Threshold Adjust
−25 0 25 50 75 100 125
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 40 80 120 160 200 240 280
−25 0 25 50 75 100 125
40 80 120 160 200 240 280 40 80 120 160 200 240 280
0
−4.0
−8.0
−12
0
−1.0
−2.0
−3.0
−40
−80
−120
−160
−200
−240
−280
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
240
200
160
120
80
40
0
−40
−80
−120
−160
−200
−240
−260
16
14
12
10
8.0
6.0
4.0
2.0
0
0
2.0
4.0
6.0
8.0
10
12
14
14
12
10
8.0
6.0
4.0
2.0
0
14
12
10
8.0
6.0
4.0
2.0
0
V
CC
= 6.0 V
1 − Source High−Side and Load High−Side
2 − Source Return Low−Side
3 − Load Low−Side
V
CC
V
CC
= 6.0 V
V
O
= 1.0 V
I
O
= 1.0 mA
T
A
= 25°C
1
2
3
V
Pin
5
V
Pin
6
−V
Pin
5
V
Pin
6
V
Pin
1
−V
Pin
6
V
CC
= 6.0 V
V
O
= 1.0 V
I
O
= 1.0 mA
Pin 1 = V
CC
T
A
= 25°C
GND
V
Pin
5
V
Pin
2
−V
Pin
1
V
CC
= 6.0 V
V
O
= 1.0 V
I
O
= 1.0 mA
T
A
= 25°C
V
Pin
2
−|V
Pin
1
|
V
Pin
5
V
CC
= 6.0 V
V
O
= 1.0 V
I
O
= 1.0 mA
T
A
= 25°C
Noninverting input path is active
for load low−side current sensing.
Inverting Amplifier is
active for source return
low−side current sensing.
GND
V
V
Pin 5
, VOLTAGE SENSING INPUT (V)
th(I HS)
, CURRENT SENSINGΔ
VΔ
th(v)
, VOLTAGE SENSING THRESHOLD CHANGE (mV)
THRESHOLD CHANGE (mV)
V
Pin 6
, CURRENT SENSE INPUT B (mV)
V
Pin 1
, CURRENT SENSE INPUT A (mV)
V
Pin 2
−V
Pin 1
, INPUT DIFFERENCE VOLTAGE (mV)
V
Pin 1
, CURRENT SENSE INPUT A (mV)
V
Pin 6
−V
Pin 5
, INPUT DIFFERENCE VOLTAGE (mV)
V
Pin 1
−V
Pin 6
, INPUT DIFFERENCE VOLTAGE (mV)
V
Pin 2
−|V
Pin 1
|, INPUT DIFFERENCE VOLTAGE (mV)
Differential Amplifier is active for
source high−side and load high−side
current sensing. Both vertical axis are
expressed in millivolts down to V
CC
.
MC33341
http://onsemi.com
5
0
1.0
0.1
8.0
1.0 k
60
0
0
0.1
8.0
1.0 k
60
V
CC
, SUPPLY VOLTAGE (V)
I
O
, DRIVE OUTPUT LOAD CURRENT (mA)
f, FREQUENCY (Hz)
I
L
, OUTPUT LOAD CURRENT (mA)
I
O
, DRIVE OUTPUT LOAD CURRENT (mA)
Figure 8. Bode Plot
Voltage Sensing Inputs to Drive Output
f, FREQUENCY (Hz)
Figure 9. Bode Plot
Current Sensing Inputs to Drive Output
Figure 10. Transconductance
Voltage Sensing Inputs to Drive Output
Figure 11. Transconductance
Current Sensing Inputs to Drive Output
Figure 12. Drive Output High State
Source Saturation versus Load Current
Figure 13. Supply Current
versus Supply Voltage
V
CC
= 6.0 V
V
O
= 1.0 V
R
L
= 1.0 k
Pin 3 = 1.0 nF
T
A
= 25°C
V
CC
= 6.0 V
V
O
= 1.0 V
R
L
= 1.0 k
Pin 3 = 1.8 nF
T
A
= 25°C
V
CC
= 6.0 V
V
O
= 1.0 V
T
A
= 25°C
V
CC
= 6.0 V
V
O
= 1.0 V
T
A
= 25°C
V
CC
= 6.0 V
T
A
= 25°C
I
O
= 0 mA
T
A
= 25°C
Gain
Phase
Gain
Phase
High−Side Sensing
Phase
Low−Side Sensing
Drive Output Low State
10 k10 k 100 k 1.0 M 100 k 1.0 M
0.2 0.3 0.5 1.0 2.0 3.0 5.0 10 0.2 0.3 0.5 1.0 2.0 3.0 5.0 10
4.0 8.0 12 16 20 4.0 8.0 12 16
50
40
30
20
10
0
50
40
30
20
10
0
6.0
4.0
2.0
0
6.0
4.0
2.0
0
−0.4
−0.8
−1.2
−1.6
−2.0
0.8
0.6
0.4
0.2
0
180
160
140
120
100
80
180
160
140
120
100
80
A
VOL(I)
, CURRENT SENSING OPEN−LOOP
φ, EXCESS PHASE (°)
VOLTAGE GAIN (dB)
A
VOL(V)
, VOLTAGE SENSING OPEN−LOOP
VOLTAGE GAIN (dB)
g
m(v)
, VOLTAGE SENSING TRANSCONDUCTANCE (mhos)
g
m(I)
, CURRENT SENSING TRANSCONDUCTANCE (mhos)
V
OH
, OUTPUT SOURCE SATURATION VOLTAGE (V)
φ, EXCESS PHASE (°)
I
CC
, SUPPLY CURRENT, DRIVE OUTPUT LOW STATE (mA)
V
CC
Drive Output High State
MC33341
http://onsemi.com
6
INTRODUCTION
Power supplies and battery chargers require precise
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
The MC33341 is an analog regulation control circuit that
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
A quad input transconductance amplifier is used to control
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.
A high impedance node within the transconductance
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 voltage that appears across the load is monitored by
the noninverting V
sen
input of the transconductance
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
th
input of the transconductance amplifier. This level is
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
S
. Under these
conditions, the voltage regulation threshold is internally
fixed at 1.2 V. In source return low−side and load low−side
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
Current sensing is accomplished by monitoring the
voltage that appears across sense resistor R
S,
level shifting
it with respect to Pin 4 if required, and applying it to the
noninverting I
sen
input of the transconductance amplifier. In
order to allow for maximum circuit flexibility, there are
three methods of current sensing, each with different
internal paths.
In source high−side (Figures 14 and 15) and load
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
S
while Pin 6 connects to the low side. Logic circuitry is
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
sen
input of the Transconductance
Amplifier. This happens if Pin 1 is less than 1.2 V or if Pin 1
is less than Pin 6.
With source return low−side current sensing (Figures 16
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
S
while Pin 4 connects to the high side. Note that
a negative voltage appears across R
S
with respect to Pin 4.
In load low−side current sensing (Figures 20 and 21) a
Noninverting input path is active with a gain of 1.0. Pin 1
connects to the high potential side of current sense resistor
R
S
while Pin 4 connects to the low side. The Noninverting
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.
The regulation threshold in all of the current sensing
modes is internally fixed at 200 mV with Pin 2 connected to
V
CC
. Pin 2 can be used to externally adjust the threshold
over a range of 0 to 200 mV with respect to the IC ground
at Pin 4.
Reference
An internal band gap reference is used to set the 1.2 V
voltage threshold and 200 mV current threshold. The
reference is initially trimmed to a ±1.0% tolerance at
T
A
= 25°C and is guaranteed to be within ±2.0% over an
ambient operating temperature range of −25° to 85°C.
Applications
Each of the application circuits illustrate the flexibility of
this device. The circuits shown in Figures 14 through 21
contain an optoisolator connected from the Drive Output at
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P19

MC33341D

Mfr. #:
Buy MC33341D
Manufacturer:
ON Semiconductor
Description:
Battery Management 2.3-15V Power Supply
Lifecycle:
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