PJ3800
Low Voltage Switching Regulator Controller
T
he PJ3800 is a single-channel switching regulator
control IC for low voltage applications incorporating a
soft start function and short circuit detection function.
SOP-8
TSSOP-8
The device has a low minimum operating voltage of 1.8 V and
is ideal for the power supply of battery-operated electronic
equipment.
.
FEATURES
Wide supply voltage operating range: 1.8 to 15 V
Low current consumption: Typically 5.5 mA in
operation, 1 mA or less in stand-by
High speed operation is possible: Maximum 1 MHz
The error amplifier gain is set inside the IC, so
peripheral components are minimized.
Incorporates a soft start circuit.
Incorporates a timer-latch type short circuit detection
circuit (SCP).
Totem-pole type output with adjustable on/off current
(for NPN transistors)
Incorporates a stand-by function.
Pin 1. Error amplifier inverting input
2. Soft Star & SCP
3. Power supply
4. Output current setting and control
5. Output
6. Ground
7. Oscillation frequency
8. Error amplifier output
ORDER INFORMATION
Device
PJ3800CS
PJ3800CA
Operation Temperature
-20 ~ +85℃
Package
SOP-8
TSSOP-8
BLOCK DIAGRAM
1-8
2003/04.rev.A
PJ3800
Low Voltage Switching Regulator Controller
ABSOLUTE MAXIMUM RATINGS
Parameter
Power supply voltage
Output source current
Output sink current
Allowable dissipation
Operating temperature
Storage temperature
Symbol
V
CC
I
O+
I
O-
P
D
T
op
T
stg
Rated Value
Min.
—
—
—
—
-30
-55
Max.
16
-50
50
570*
+85
+125
Unit
V
mA
mA
mW
℃
℃
*
: When mounted on a 10 cm square double-sided epoxy board
WARNING: Semiconductor devices can be permanently damaged by application of stress (voltage, current, temperature, etc.)
in excess of absolute maximum ratings. Do not exceed these ratings.
RECOMMENDED OPERATING CONDITIONS
Values
Min.
1.8
–0.2
–0.2
–40
—
—
—
150
1
100
10
–30
Typ.
—
—
—
—
—
0.1
0.1
390
3
270
500
+25
Max.
15
1
VCC
—
40
—
—
5000
10
10000
1000
+85
Parameter
Power supply voltage
Error amplifier input voltage
BR/CTL pin input voltage
Output source current
Output sink current
SCP pin capacitance
Phase compensation capacitance
Output current setting resistance
Timing resistance
Timing capacitance
Oscillation frequency
Operating temperature
Symbol
V
CC
V
I
V
BR
I
O+
I
O–
C
PE
C
P
R
B
R
T
C
T
f
OSC
T
OP
Unit
V
V
V
mA
mA
μF
μF
Ω
kΩ
pF
kHz
℃
WARNING: Recommended operating conditions are normal operating ranges for the semiconductor device. All the device’s
electrical characteristics are warranted when operated within these ranges.
Always use semiconductor devices within the recommended operating conditions. Operation outside
these ranges may adversely affect reliability and could result in device failure.
No warranty is made with respect to uses, operating conditions, or combinations not represented on the data sheet.
Users considering application outside the listed conditions are advised to contact their Promax Johnton
representative beforehand.
2-8
2003/04.rev.A
PJ3800
Low Voltage Switching Regulator Controller
ELECTRICAL CHARACTERISTICS
(
VCC = +2 V, Ta = +25 °C)
Parameter
Circuit to prevent
Reset voltage
malfunction at low
input voltage (U.V.L.O.) Threshold voltage
Charging current
Soft start
Voltage at soft start completion
Short circuit
detection (S.C.P.)
Saw tooth wave
oscillator (OSC)
Charging current
Threshold voltage
Oscillation frequency
Frequency input stability
Frequency variation with
temperature
Input threshold voltage
VT input stability
VT variation with temperature
Input bias current
Error amplifier
Voltage gain
Frequency bandwidth
Maximum output
voltage range
Output source current
Output sink current
Idle period
adjustment section
Maximum duty cycle
Symbol
V
V
TH
I
CS
V
tS
I
CPC
V
tPC
f
OCS
f
dV
f
dT
V
T
V
TdV
V
TdT
I
B
A
V
BW
V
OM+
V
OM-
I
OM+
I
OM
-
t
DUTY
V
OH1
V
OH2
Output voltage
Output section
Output source current
Output sink current
Pull down resistance
Pin voltage
Output current
setting section/
Control section
Input off condition
Input on condition
Pin current range
Entire device
Stand-by current
Average supply current
t
V
OL1
V
OL2
I
O+
I
O-
R
O
V
BR
I
OFF
I
ON
I
BR
I
CCS
I
CC
BR/CTL pin open or V
CC
R
B
= 390Ω
—
Condition
—
VSCP = 0 V
—
VSCP = 0 V
—
R
T
=3.0kΩ, C
T
= 270 pF
VCC = 2 V to 15 V
Ta =-20℃ to +85℃
V
FB
= 450 mV
V
CC
= 2 V to 15 V
Ta =-20℃ to +85℃
V
IN
= 0 V
—
AV = 0 dB
—
VFB = 0.45 V
R
T
=3.0kΩ,C
T
=270pF
VFB =0.8V
R
B
= 390ΩI
O
=-15mA
R
B
=750Ω,V
CC
=1.8V
I
O
= -10mA
R
B
= 390Ω,I
O
=15mA
R
B
= 750Ω V
CC
=1.8V
I
O
= 10mA
R
B
= 390Ω V
O
= 0.9V
R
B
= 390Ω V
O
= 0.3V
—
R
B
= 390Ω
Value
Min.
—
1.1
-0.5
0.7
-1.5
0.7
400
—
—
480
—
—
-1.0
70
—
0.78
—
—
24
65
1.0
0.8
—
—
—
30
20
0.2
-20
—
-1.8
—
—
Typ.
—
1.3
-1.0
0.8
-1.0
0.8
500
2
5
500
5
1
-0.2
100
6
0.87
0.05
-40
40
75
1.2
1
0.1
0.1
-30
60
30
0.3
—
—
—
—
5.5
Max.
0.9
1.5
-0.7
0.9
-0.7
0.9
600
10
—
520
20
—
1.0
145
—
—
0.2
-24
—
85
—
—
0.2
0.2
-20
—
40
0.4
0
-45
-0.1
1
9.3
Unit
V
V
μA
V
μA
V
kHz
%
%
mV
mV
%
μA
V/V
MHz
V
V
μA
μA
%
V
V
V
V
mA
mA
k
V
μA
μA
mA
μA
mA
3-8
2003/04.rev.A
PJ3800
Low Voltage Switching Regulator Controller
DIAGRAM
HOW TO SET THE TIME CONSTANT FOR SOFT START AND SHORT CIRCUIT DETECTION
1. Soft Start
At power on, the capacitor
CPE
connected to the SCP pin starts charging. The PWM comparator compares the soft start setting
voltage as a proportion of the voltage at the SCP pin with the saw tooth waveform. The comparison controls the ON duty of the
OUT pin, causing the soft start operation. On completion of soft start operation, the voltage at the SCP pin stays low, the soft
start setting voltage stays high, and the circuit enters the output short circuit detection wait state.
Soft start time (The time until the output ON duty reaches approximately 50%)
tS [s]
≅
0.35
×
C
PE
[μF]
2. Short Circuit Protection
If
the switching regulator output suddenly drops due to load effect, the error amplifier output (FB pin) is fixed at VOM + and
capacitor CPE starts charging. When the voltage at the SCP pin reaches approximately 0.8V, the output pin is set low and the
SCP pin stays low.
Once the protection circuit operates, the circuit can be restored by resetting the power supply.
• Short circuit detection time
t
PE
[s]
≅
0.8
×
C
PE
[μF]
4-8
2003/04.rev.A
PJ3800
Low Voltage Switching Regulator Controller
TYPICAL CHARACTERISTICS
5-8
2003/04.rev.A
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