DATA SHEET
BiCMOS INTEGRATED CIRCUIT
µ
PC1935
DC-DC CONVERTER CONTROL IC
DESCRIPTION
The
µ
PC1935 is a low-voltage input DC-DC converter control IC that can configure a three-output (step-up
×
2, inverted
output
×
1) DC-DC converter at an input voltage of 3, 3.3, or 5 V.
Because of its wide operating voltage range, this IC can also be used to control DC-DC converters using an AC adapter
for input.
FEATURES
•
Low supply voltage: 2.5 V (MIN.)
•
Operating voltage range: 2.5 to 20 V (breakdown voltage: 30 V)
•
Can control three output channels.
•
Timer latch circuit for short-circuit protection.
•
Ceramic capacitor with low capacitance (0.1
µ
F) can be used for short-circuit protection.
•
Dead times of channels 2 (step-up) and 3 (inverted output) can be set from external resistors. Dead time of channel 1
(step-up) is internally fixed to 85 %.
•
Soft start of each channel can be set independently.
•
Each channel can be turned ON/OFF independently.
ORDERING INFORMATION
Part Number
Package
16-pin plastic TSSOP (5.72 mm (225))
µ
PC1935GR
The information in this document is subject to change without notice. Before using this document, please
confirm that this is the latest version.
Not all devices/types available in every country. Please check with local NEC representative for
availability and additional information.
Document No. G13418EJ3V0DS00 (3rd edition)
Date Published March 2000 NS CP (K)
Printed in Japan
The mark
5
shows major revised points.
1998
µ
PC1935
BLOCK DIAGRAM
Channel 3: for inversion
DTC
3
16
I
l3
15
FB
3
14
OUT
3
13
DTC
2
12
I
l2
11
Channel 2: for step-up
FB
2
10
OUT
2
9
–
+
–
–
+
–
+
+
+
–
Internal
fixed
voltage
Internal
fixed
voltage
Soft start select switch
+
–
+
Internal
fixed
voltage
–
Reference
voltage
section
Oscillation
section
Timer latch for
short-circuit
protection section
+
Internal
fixed
voltage
6
7
FB
1
Channel 1: for step-up
8
OUT
1
1
V
CC
2
V
REF
3
R
T
4
GND
5
DLY
I
I1
2
Data Sheet G13418EJ3V0DS00
µ
PC1935
PIN CONFIGURATION (Top view)
16-pin plastic TSSOP (5.72 mm (225))
•
µ
PC1935GR
V
CC
V
REF
R
T
GND
DLY
I
I1
FB
1
OUT
1
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
DTC
3
I
I3
FB
3
OUT
3
DTC
2
I
I2
FB
2
OUT
2
PIN FUNCTIONS
Pin No.
1
2
3
4
5
Symbol
V
CC
V
REF
R
T
GND
DLY
Power supply
Reference voltage output
Frequency setting resistor connection
Ground
Short-circuit protection/channel 1 soft
start capacitor connection
6
7
8
I
I1
FB
1
OUT
1
Channel 1 error amplifier inverted input
Channel 1 error amplifier output
Channel 1 open-drain output
14
15
16
FB
3
I
I3
DTC
3
Channel 3 error amplifier output
Channel 3 error amplifier inverted input
Channel 3 dead time setting
Function
Pin No.
9
10
11
12
13
Symbol
OUT
2
FB
2
I
I2
DTC
2
OUT
3
Function
Channel 2 open-drain output
Channel 2 error amplifier output
Channel 2 error amplifier inverted input
Channel 2 dead time setting
Channel 3 open-drain output
Data Sheet G13418EJ3V0DS00
3
µ
PC1935
CONTENTS
1. ELECTRICAL SPECIFICATIONS ................................................................................................................ 5
2. CONFIGURATION AND OPERATION OF EACH BLOCK.................................................................... 11
2.1 Reference Voltage Generator ...........................................................................................................................12
2.2 Oscillator ...........................................................................................................................................................12
2.3 Under Voltage Lock-out Circuit ........................................................................................................................12
2.4 Error Amplifiers.................................................................................................................................................12
2.5 PWM Comparators............................................................................................................................................12
2.6 Timer Latch-Method Short Circuit Protection Circuit ....................................................................................13
2.7 Output Circuit....................................................................................................................................................13
3. NOTES ON USE........................................................................................................................................ 14
3.1 Setting the Output Voltage ...............................................................................................................................14
3.2 Setting the Oscillation Frequency ...................................................................................................................15
3.3 Preventing Malfunction of the Timer Latch-Method Short Circuit Protection Circuit..................................15
3.4 Connecting Unused Error Amplifiers ..............................................................................................................16
3.5 ON/OFF Control.................................................................................................................................................17
3.5.1 Channel 1 (for step-up) ............................................................................................................................17
3.5.2 Channel 2 (for step-up) ............................................................................................................................18
3.5.3 Channel 3 (for inverted output) ................................................................................................................19
3.6 Maximum Duty Limit .........................................................................................................................................20
3.7 Notes on Actual Pattern Wiring........................................................................................................................20
4. APPLICATION EXAMPLE ......................................................................................................................... 21
4.1 Application Example.........................................................................................................................................21
4.2 List of External Parts ........................................................................................................................................22
5. PACKAGE DRAWING ................................................................................................................................ 23
6. RECOMMENDED SOLDERING CONDITIONS ....................................................................................... 24
4
Data Sheet G13418EJ3V0DS00
µ
PC1935
1.
ELECTRICAL SPECIFICATIONS
Absolute Maximum Ratings (unless otherwise specified, T
A
=
25
°
C)
Parameter
Supply voltage
Output voltage
Output current (open drain output)
Total power dissipation
Operating ambient temperature
Storage temperature
Symbol
V
CC
V
O
I
O
P
T
T
A
T
stg
Ratings
30
30
21
400
–20 to + 85
–55 to + 150
Unit
V
V
mA
mW
°C
°C
Caution
Product quality may suffer if the absolute maximum rating is exceeded even momentarily for any
parameter. That is, the absolute maximum ratings are rated values at which the product is on the verge
of suffering physical damage, and therefore the product must be used under conditions that ensure
that the absolute maximum ratings are not exceeded.
Recommended Operating Conditions
Parameter
Supply voltage
Output voltage
Output current
Operating temperature
Oscillation frequency
Symbol
V
CC
V
O
I
O
T
A
f
OSC
−20
20
MIN.
2.5
0
TYP.
MAX.
20
20
20
+85
800
Unit
V
V
mA
°C
kHz
Caution
The recommended operating range may be exceeded without causing any problems provided that the
absolute maximum ratings are not exceeded. However, if the device is operated in a way that exceeds
the recommended operating conditions, the margin between the actual conditions of use and the
absolute maximum ratings is small, and therefore thorough evaluation is necessary. The recommended
operating conditions do not imply that the device can be used with all values at their maximum values.
Data Sheet G13418EJ3V0DS00
5
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