BiCMOS
INTEGRATED CIRCUIT
PC1935
µ
µ
µ µ
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.
FEATUR ES
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
•
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
PC1935GR 16-pin plastic TSSOP (5.72 mm (225))
µ
F) can be used for short-circuit protection.
µ
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 ★ shows major revised points.
1998
BLOCK DIAGRAM
µ
µ
µ µ
1935
DTC3I
Channel 3: for inversion
l3
FB
3
OUT
DTC
3
2
Channel 2: for step-up
I
l2
FB
2
OUT
16 15 14 13 12 11 10 9
–
+
Internal
fixed
voltage
–
–+
+
–
+
Internal
fixed
voltage
+
–
Internal
fixed
voltage
+
–
+
Reference
voltage
section
Oscillation
section
Soft start select switch
Timer latch for
short-circuit
protection section
–
+
Internal
fixed
voltage
12 345 6 7 8
V
CC
V
REF
R
T
DLY GND I
I1
FB
1
2
OUT
1
Channel 1: for step-up
2
Data Sheet G13418EJ3V0DS00
PIN CONFIGURATION (Top view)
16-pin plastic TSSOP (5.72 mm (225))
PC1935GR
••••
µµµµ
GND
OUT
V
V
REF
R
DLY
FB
µ
µ
µ µ
DTC
I
I3
FB
OUT
DTC
I
I2
FB
OUT
3
3
3
2
2
2
CC
T
I1
I
1
1
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
1935
PIN FUNCTIONS
Pin No. Symbol Function Pin No. Symbol Function
1VCCPower supply 9 OUT
2V
REF
Reference voltage output 10 FB
3RTFrequency setting resistor connection 11 I
4 GND Ground 12 DTC
5 DLY Short-circuit protection/channel 1 sof t
13 OUT
start capacitor connection
6II1Channel 1 error amplifier inverted input 14 FB
7F B1Channel 1 error amplifier output 15 I
8O U T1Channel 1 open-drain output 16 DTC
2
Channel 2 open-drain output
2
I2
3
I3
Channel 2 error amplifier output
Channel 2 error amplifier inverted input
2
Channel 2 dead time setting
3
Channel 3 open-drain output
Channel 3 error amplifier output
Channel 3 error amplifier inverted input
3
Channel 3 dead time setting
Data Sheet G13418EJ3V0DS00
3
µ
µ
µ µ
1935
CONTENTS
1. ELECTRICAL SPECIFICATIONS................................................................................................................5
2. CONFIGURATION AND OPERATION OF EACH BLOCK....................................................................11
2.1 Reference V oltage 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
1. ELECTRICAL SPECIFICATIONS
µ
µ
µ µ
1935
Absolute Maximum Ratings (unless otherwise specified, TA
Parameter Symbol Ratings Unit
Supply voltage V
Output voltage V
Output current (open drain output) I
Total power dissipation P
Operating ambient temperature T
Storage temperature T
CC
O
O
T
A
stg
====
25
C)
°°°°
30 V
30 V
21 mA
400 mW
–20 to + 85
–55 to + 150
°
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 Symbol MIN. TYP. MAX. Unit
O
OSC
CC
O
A
2.5 20 V
02 0 V
20 mA
−
20
20 800 kHz
+
85
°
C
Supply voltage V
Output voltage V
Output current I
Operating temperature T
Oscillation frequency f
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
µ
µ
µ µ
1935
Electrical Characteristics (unless otherwise specified, TA = 25
C, VCC
°°°°
3 V, f
====
= 100 kHz)
OSC
Block Parameter Symbol Conditions MIN. TYP. MAX. Unit
Under
voltage
lock-out
section
Reference
voltage
section
section
Duty setting
section
Start-up voltage V
Operation stop voltage V
Hysteresis voltage V
Reset voltage (timer latch) V
Reference voltage V
CC (L-H)
CC (H-L)
H
CCR
REF
Line regulation REG
Load regulation REG
Temperature coefficient
OSC
f
setting accuracy
OSC
f
total stabilit y
Input bias current I
Channel 1 maximum duty D
Channel 1 soft start time t
Low-level threshold voltage V
∆
∆
∆
V
f
f
BD
MAX.
SS
TH (L)
OSC
OSC
IN
L
REF
REF
I
= 0.1 mA 1.57 V
REF
I
= 0.1 mA 1.5 V
REF
I
= 0.1 mA 30 70 mV
REF
I
= 0.1 mA 1.0 V
REF
I
= 1 mA 2.0 2.1 2.2 V
CC
≤
2.5 V≤V
0.1 mA≤I
/∆T−20 °C≤T
RT = 18 k
−
20 °C≤T
2.5 V≤V
20 V 2 12.5 mV
REF
≤
1 mA 1 7.5 mV
A
≤+
Ω−
A
≤+
CC
≤
20 V
85 °C, I
85 °C,
REF
= 0 A 0.5 %
20
−
30
(Channels 2 and 3 only) 1.0
DLY
C
= 0.1 µF5 0 m s
Duty = 0 % (channels 1 and2)
+
+
85 %
1.2 V
Duty = 100 % (channel 3)
High-level threshold voltage V
TH (H)
Duty = 100 % (channel 2)
1.6 V
Duty = 0 % (channel 3)
Error
amplifier
section
Input threshold voltage V
Input bias current I
Open loop gain A
Unity gain f
Maximum output voltage (+)
Maximum output voltage (−)
Maximum sink current I
Output source current I
Output
section
Output ON voltage V
Rise time t
Fall time t
Short-circuit
Input sense voltage V
protection
section
UV sense voltage V
Source current on short-circuiting I
Delay time t
Overall Circuit operation current I
ITH
B
v
unity
OM
V
OM
V
Osink
Osource
OL
r
f
TH1
TH3
V
UV
OUV
DLY
CC
+
−
, V
0.285 0.3 0.315 V
−
100
+
VO = 0.3 V 70 80 dB
VO = 0.3 V 1.5 MHz
IO = −45 µA1 . 6 2 V
IO = 45 µA 0.02 0.5 V
VFB = 0.5 V 0.8 1.4
VFB = 1.6 V
RL = 150
RL = 150
RL = 150
TH2
Channels 1 and 2 1.75 1.9 2.05 V
Ω
Ω
Ω
−
0.2 0.6 V
−
70
50 ns
50 ns
Channel 3 0.5 0.63 0.75 V
0.8 0.85 V
1.0 1.6 2.7
DLY
C
= 0.1 µF5 0 m s
VCC = 3 V 1.8 3.1 5.1 mA
30 % Oscillation
50 %
µ
100 nA
µ
µ
45
µ
A
A
A
A
Caution Connect a capacitor of 0.01 to 10
PC1935 C
6
F to the V
µ
µ
µ µ
REF
pin.
2
4
Data Sheet G13418EJ3V0DS00
REF
= 0.01 to 10 F
µ µ
Timing Charts (sequence operation of power application
1
FB
Channel 1
DLY
OUT
1
Channel 1 starts.
Data Sheet G13418EJ3V0DS00
Channel 2
→ channel 1 → channel 2 → channel 3)
OFF
FB
ON
2
DTC
2
7
OUT
Channel 3
OUT
2
Channel 2 starts.
3
OFF
ON
DTC
3
FB
3
Channel 3 starts.
OFF
ON
µ µ
µ
µ
PC1935
µ
µ
µ µ
1935
Typical Characteristic Curves (unless otherwise specified, VCC = 3 V, f
PT vs T
A
0.5
(W)
0.4
T
312.5 ° C/W
0.3
0.2
0.1
Total power dissipation P
0
0 012345 25 50 75
Operating ambient temperature T
V
REF
vs T
2.13
I
REF
= 0 A
2.12
(V)
REF
2.11
100 125 150
A
(° C)
A
2.5
2.0
(V)
REF
1.5
1.0
0.5
Reference voltage V
0
1000
(kHz)
OSC
100
= 100 kHz, TA = 25
OSC
V
REF
I
REF
= 0 A
Supply voltage V
OSC
f
vs V
vs R
C) (Nominal)
°°°°
CC
CC
(V)
T
2.10
2.09
2.08
Reference voltage V
2.07
–25 0 25 50 75 100
Operating ambient temperature T
∆ f
OSC
vs T
A
8
R
T
(%)
OSC
= 18 kΩ
4
0
–4
–8
Oscillation frequency accuracy ∆ f
–25 0 25 50 75 100
Operational ambient temperature T
A
(° C)
A
(° C)
10
Oscillation frequency f
1
1 10 100
Timing resistance R
VOL vs I
T
(kΩ)
O
0.5
0.4
(V)
OL
0.3
0.2
0.1
Output ON voltage V
0
0 4 8 12 16 20 2 6 10 14 18
Output current I
O
(mA)
8
Data Sheet G13418EJ3V0DS00
µ
µ
µ µ
1935
VOL vs T
0.4
A
D
MAX.
vs R
T
90
IO = 20 mA
(%)
(V)
OL
0.3
0.2
0.1
MAX.
80
70
60
Output ON voltage V
Channel maximum duty D
1.24
(V)
TH (L)
1.22
1.20
50
Timing resistance R
V
RT = 18 kΩ
TH (L)
vs T
T
(kΩ )
A
0
–25 0 25 50 75 100 1 10 100
Operating ambient temperature T
V
TH (H)
vs T
A
A
(° C)
1.64
RT = 18 kΩ
(V)
TH (H)
1.62
1.60
1.58
High-level threshold voltage V
1.56
–25 0 25 50 75 100 –25 0 25 50 75 100
Operating ambient temperature T
t
SS
vs C
DLY
A
(° C)
600
500
(ms)
SS
400
300
200
100
Channel soft start time t
0 0.2 0.4 0.6 0.8 1
DLY pin capacitor capacitance C
DLY
µ
( F)
1.18
Low-level threshold voltage V
1.16
Operating ambient temperature T
t
DLY
vs C
(ms)
600
DLY
DLY
500
400
300
200
100
0
Short-circuit protection circuit delay time t
0.2 0.4 0.6 0.8 1
DLY pin capacitor capacitance C
DLY
A
(° C)
µ
( F)
Data Sheet G13418EJ3V0DS00
9