Holtek HT77S11 High efficiency synchronous step-up dc/dc converter Datasheet

HT77S10/HT77S11
High Efficiency Synchronous Step-Up DC/DC Converter
Features
· Low start-up voltage: 0.7V (Typ.)
· Low ripple and low noise
· High efficiency: HT77S10: 91% (Typ.)
· Ultra low supply current: 20mA (Typ.)
at IOUT=200mA, VIN=2.4V, VOUT=3.3V
· Low shutdown current: 1mA (Max.)
· High output voltage accuracy: ±4%
· Built-in voltage detector
· Output voltage: 3.3V, 5.0V or Adjustable
· 8-pin MSOP/SOP packages
Applications
· Battery-powered equipment power source
· Power source for appliances, which require a higher
operating voltage than that of the application
batteries
· Power source for cameras, camcorders, VCRs,
PDAs, pagers, electronic data banks, and
hand-held communication equipment
General Description
The HT77S11 and HT77S10 are high efficiency PFM
synchronous step-up DC-DC converters. The two devices although functionally similar are different in their
output drive current capabilities. Synchronous rectification operation is used to increase device efficiency and
to reduce the external component resulting in reduced
product costs. The converter switching frequency, which
can have a value up to 500KHz, will vary according to
the load demands and according to the input voltage to
keep the output voltage at the required level.
The HT77S11 and HT77S10 have 0.7V start-up voltage,
and will consume a typical quiescent current of 20mA. A
shutdown mode is provided whereby the operating current will be reduced a very low value. The output voltage
has two fixed voltages of 3.3V by setting FB to OUT pin
and 5V by setting FB to GND pin, but can also be adjusted between a value of 1.8V~5.5V using two external
resistors. With internal voltage detector function, the detected voltage can be set by using dividing resistor.
Selection Table
Part No.
Current Limit
HT77S10
1.0A
HT77S11
0.55A
Package
8MSOP/SOP
Rev. 1.10
1
March 11, 2010
HT77S10/HT77S11
Block Diagram
Note:
* The FB pin is connected to an external resistive divider, OUT or GND pins to set the output voltage.
Pin Assignment
F B
L B I
L B O
R E F
1
8
2
7
3
6
4
5
O U T
L X
G N D
S H D N
H T 7 7 S 1 0 /H T 7 7 S 1 1
8 M S O P -A /S O P -A
Rev. 1.10
2
March 11, 2010
HT77S10/HT77S11
Pin Descriptions
Pin No.
Pin Name
Description
1
FB
Feedback Input Pin.
This pin is used to select the required output voltage. It can be connected to an external resistor divider for a user selected voltage or to either the OUT or GND pins for a fixed voltage.
GND: 5V output
OUT: 3.3V output
Resistor Divider: 1.8V~5.5V range output
2
LBI
Low-Battery Comparator Input Pin.
This pin is connected to the internal low battery voltage comparator. If the voltage on this pin
is less than the REF voltage - nominally 1.3V - then the LBO output will be low.
3
LBO
Open-Drain Low Battery Comparator Output.
This pin is used to indicate a low battery condition and is connected to the low battery voltage
comparator output. Note that the pin will be in a high impedence condition when the device is
in the shutdown mode.
High Z: VLBI > VREF
0: VLBI < VREF
4
REF
Reference Voltage Output Pin.
This pin is the output from the voltage reference generator and should be connected to a
0.1mF bypass capacitor.
5
SHDN
6
GND
7
LX
8
OUT
Shutdown Input Pin.
This pin is used to power down the device and place it into the shutdown mode.
High: Device in normal operating mode
Low: Device in shutdown mode
Ground Pin.
Switching Output Pin.
This pin is the device switching output pin which is connected to the internal N-channel and
P-channel switching power MOSFET drain pins.
Power Output Pin.
This pin is the converter output pin. It also supplies bootstrap power to the device.
Absolute Maximum Ratings
Supply Voltage ........................................-0.3V to 7.0V
Storage Temperature ...........................-50°C to 125°C
Operating Temperature ..........................-40°C to 85°C
Note: These are stress ratings only. Stresses exceeding the range specified under ²Absolute Maximum Ratings² may
cause substantial damage to the device. Functional operation of this device at other conditions beyond those listed
in the specification is not implied and prolonged exposure to extreme conditions may affect device reliability.
Rev. 1.10
3
March 11, 2010
HT77S10/HT77S11
Electrical Characteristics
VIN=2V, SHDN=FB=OUT, VOUT=3.3V, refer to figure 1 unless otherwise specified, Ta=25°C
Symbol
Parameter
Test Conditions
Min.
Typ.
Max.
Unit
VIN
Operating Input Voltage
¾
¾
¾
5.5
V
VIN-MIN
Minimum Input Voltage
¾
¾
0.7
¾
V
VIN-START
Start-up Input Voltage
RL=3kW
¾
0.7
0.9
V
FB=OUT
3.17
3.30
3.43
V
FB=GND
4.80
5.00
5.20
V
VIN < VOUT, FB using two
external resistors
1.80
¾
5.50
V
IREF=0
1.268
1.300
1.333
V
VOUT
Output Voltage
VREF
Reference Voltage
VREF-LOAD Reference Load Regulation
IREF=0 to 150mA
¾
10
30
mV
VREF-LINE
Reference Line Regulation
VOUT= 2V to 5.5V
¾
5
10
mV/V
RDS(ON)
Internal PMOS and
N-MOS On Resistance
IL=100mA
¾
0.3
¾
W
ILIM
Internal NMOS Switch
Current Limit
HT77S10
0.80
1.00
1.20
A
HT77S11
0.40
0.55
0.75
A
ILEAK
Internal N-MOS Leakage Current VLX=4V, VOUT=5.5V
1.00
mA
¾
0.05
HT77S10
300
350
¾
mA
HT77S11
150
300
¾
mA
HT77S10
180
230
¾
mA
HT77S11
90
160
¾
mA
VFB=1.4V, VOUT=3.3V
¾
20
35
mA
¾
1.268
1.300
1.333
V
¾
FB=OUT
IOUT
Steady-State Output Current
FB=GND
IQ
Quiescent Current
VFB
FB Input Threshold
VLBI
LBI Input Threshold
1.268
1.300
1.333
V
LBO Low Output Voltage
VLBI=0, ISINK=1mA
¾
0.2
0.4
V
ILBO
LBO Off Leakage Current
VLBO =5.5V, VLBI=5.5V
¾
0.07
1.00
mA
ISHDN
Shutdown Current
SHDN=GND
¾
0.1
1
mA
VIH
SHDN Pin Voltage High
¾
1.5
¾
¾
V
VIL
SHDN Pin Voltage Low
¾
VLBO
tON(MAX)
tOFF(MIN)
h
Note:
¾
¾
0.4
V
LX Switch On Time
VFB=1V, VOUT=3.3V
2
4
7
ms
LX Switch Off Time
VFB=1V, VOUT=3.3V
0.6
0.9
1.4
ms
VOUT=3.3V, IO=200mA
¾
90
¾
%
VIN=1.1V,VOUT=2.0V,
IO=1mA
¾
85
¾
%
Efficiency
Absolute maximum ratings indicate limits beyond which damage to the device may occur. Operating Ratings
indicate conditions for which the device is intended to be functional, but do not guarantee specific performance
limits. The guaranteed specifications apply only for the test conditions listed.
Specifications are production tested at Ta=25 degree. Specifications over -40 to 85 degree operating temperature range are assured by design.
Rev. 1.10
4
March 11, 2010
HT77S10/HT77S11
Typical Performance Characteristics
Start-Up Voltage vs. Output Current
1.8
Start-Up Voltage (V)
1.6
1.4
1.2
VOUT=5V
1.0
0.8
VOUT=3.3V
0.6
HT77S10
L=22uH
CIN=47uF
COUT=47uF
0.4
0.2
0.0
0.1
1.0
10.0
100.0
Output Current (mA)
Efficiency vs. Output Current
100%
90%
80%
VIN=3.6V
Efficiency
VIN=2.4V
VIN=1.2V
70%
60%
50%
HT77S10
VOUT=5V
L=22uH
CIN=47uF
COUT=47uF
40%
30%
20%
10%
0%
0.1
1.0
10.0
100.0
1000.0
Output Current (mA)
Efficiency vs. Output Current
100%
90%
80%
Efficiency
VIN=2.4V
VIN=1.2V
70%
60%
50%
HT77S10
VOUT=3.3V
L=22uH
CIN=47uF
COUT=47uF
40%
30%
20%
10%
0%
0.1
1.0
10.0
100.0
1000.0
Output Current (mA)
Rev. 1.10
5
March 11, 2010
HT77S10/HT77S11
Ripple Voltage vs Output Current
Ripple Voltage (mV)
220
VIN=2.4V
200
180
VIN=3.6V
160
140
120
100
80
60
HT77S10
VOUT=5V
L=22uH
CIN=47uF
COUT=47uF
VIN=1.2V
40
20
0
0
50
100 150 200 250 300 350 400 450 500 550 600 650
Output Current (mA)
Ripple Voltage (mV)
Ripple Voltage vs Output Current
260
240
220
200
180
160
140
120
100
80
60
40
20
0
VIN=2.4V
VIN=1.2V
HT77S10
VOUT=3.3V
L=22uH
CIN=47uF
COUT=47uF
0
50
100
150
200
250
300
350
400
450
500
550
600
Output Current (mA)
Ripple Voltage vs Output Current
Ripple Voltage (mV)
240
HT77S10
VOUT=5V
L=22uH
CIN=100uF
COUT=100uF
200
160
VIN=2.4V
120
VIN=3.6V
80
40
VIN=1.2V
0
0
100
200
300
400
500
600
700
800
Output Current (mA)
Rev. 1.10
6
March 11, 2010
HT77S10/HT77S11
Ripple Voltage vs Output Current
Ripple Voltage (mV)
140
120
VIN=2.4V
100
80
60
HT77S10
VOUT=3.3V
L=22uH
CIN=100uF
COUT=100uF
40
VIN=1.2V
20
0
0
50
100
150
200
250
300
350
400
450
500
550
Output Current (mA)
Functional Description
These devices use minimum off-time, current limited
pulse-frequency modulation, PFM, techniques for output voltage regulation. The PFM control circuitry acts to
control the energy stored in an external inductor to regulate the output voltage to the correct level. Using PFM
for control offers the advantages of very low quiescent
currents.
· OFF Step
The energy stored in the inductor during the ON Step
is now transferred to the load via the synchronous
switch for a minimum time of 0.9ms. When the output
voltage is less than the required regulated voltage the
synchronous switch will switch off which will reduce
the inductor current to zero. It is during this cycle that
the PMOS power transistor is switched on which
shunts its body diode, resulting in enhanced conversion efficiency.
As the design of these devices uses an internal synchronous rectifier, there is no requirement to provide the
usual external Schottky diode. This gives users the advantage of smaller circuit board areas and reduced
costs.
The device output voltage is continuously monitored using an internal comparator. The output status of the
comparator is then used to determine what action the
control logic should take to correct any differences between the actual output voltage and the required voltage. The variable switching frequency depends upon
the input voltage and the load demands but can have a
frequency of up to 500kHz. The maximum current of the
internal NMOS power switching transistor is fixed at 1A
for the HT77S10 and 0.55A for the HT77S11.
Low Voltage Start-up
These devices can provide a very low start up voltage
down to 0.7V. When power is first applied, the synchronous switch will be initially off but energy will be transferred to the load through its intrinsic body diode.
The switching frequency is controlled by two internal
single shot circuits that generate pulses of 0.9ms typical
minimum off-time and 4ms typical maximum on-time. If
the circuitry detects that the output voltage is lower than
the required voltage, the control circuitry will ensure that
more inductor energy is transferred to the load. Refer to
the block diagram to see how this regulation is implemented using the following two ON and OFF steps:
Voltage Reference
The internal voltage reference circuit supplies a nominal
voltage of 1.3V on the REF pin. Up to 150mA can be
sourced on this pin for use by external circuits. The reference voltage provided here offers excellent load regulation characteristics, however a bypass capacitor of
0.1mF should be connected for proper operation.
· ON Step
During this step, the NMOS transistor will be switched
on which effectively connects the LX pin to ground,
and allows energy to build up in the inductor as supplied by VIN. Inductor energy build up is allowed to
continue until the inductor current reaches a maximum of 1A for the HT77S10 and 0.55A for the
HT77S11 or if the on time exceeds 4ms.
Rev. 1.10
7
March 11, 2010
HT77S10/HT77S11
Shutdown
Inductor Selection
During normal device operation, the SHDN pin should
be either high or connected to the OUT pin. When the
device is in the shutdown mode, that is when the SHDN
pin is pulled low, the internal circuitry will be switched off,
thus reducing the current demands on the VIN power
source. During shutdown, the PMOS power transistor
body diode will allow current to flow from VIN to VOUT,
therefore VOUT falls to a value of approximately VIN 0.6V.
Selecting a suitable inductor is an important consideration as it is usually a compromise situation between the
output current requirements, the inductor saturation
limit and the acceptable output voltage ripple. Lower
values of inductor values can provide higher output currents but will suffer from higher ripple voltages and reduced efficiencies. Higher inductor values can provide
reduced output ripple voltages and better efficiencies,
but will be limited in their output current capabilities. For
all inductors it must be noted however that lower core
losses and lower DC resistance values will always provide higher efficiencies.
Low Battery Detection
A low battery detector function is provided in the device
using an internal comparator. The output pin LBO is the
output and input pin LBI is the input for this function. As
this is an open-drain NMOS type output, it is usually
necessary to connect an external pull-high resistor for
proper use. This pin can be pulled-high up to a voltage
of 6V independently of the OUT pin voltage. When the
voltage on LBI is higher than the threshold voltage, the
LBO output will be high impedance. If the low battery detection function is not used, the LBI and LBO pins
should be grounded. The LBI threshold voltage is set
using two external resistors, R3 and R4. The R3 and R4
ratio can be calculated using the following equation.
See Figure.1, Figure.2 and Figure.3:
The peak inductor current can be calculated using the
following equation:
Where
VIN = Input Voltage
VOUT = Output Voltage
IO = Output Current
h = Efficiency
Ts = Period
L = Inductor
R 3 VIN
-1
=
R 4 VREF
Capacitor Selection
As the output capacitor selected affects both efficiency
and output ripple voltage, it must be chosen with care to
achieve best results from the converter. Output voltage
ripple is the product of the peak inductor current and the
output capacitor equivalent series resistance or ESR for
short. It is important that low ESR value capacitors are
used to achieve optimum performance. One method to
achieve low ESR values is to connect two or more filter
capacitors in parallel. The capacitors values and rated
voltages are only suggested values.
Where
VIN = Input Voltage, VIN > VREF
Reference Voltage VREF = 1.3V
Application Information
Output Voltage Selection
The required output voltage is controlled using the FB
pin. Two fixed voltages of 3.3V and 5V are available or
an adjustable output voltage which is set using an external resistor divider.
VOUT
FB pin
3.3V
Connect OUT
5.0V
Connect to GND
1.8V£VOUT£5.5V
Connect to resistive divider
(Figure.3)
R1
)
VOUT= VREF (1+
R2
Where
VREF= Reference Voltage is 1.3V
A recommended value for R2 is 240kW.
Rev. 1.10
8
March 11, 2010
HT77S10/HT77S11
Layout Guidelines
· A star ground connection should be used to connect
Good PCB layout is an extremely important factor is ensuring the optimum performance from switching regulator converters. Poorly thought out circuit layout can
result in related noise problems. In order to minimise
both EMI and switching noise, the follow guidelines
should be followed:
the input capacitor, C1, output capacitors, C3 and C4,
and the IC GND pin
· Feedback resistors must be kept close as close to the
FB pin as possible to limit the possibility of noise injection onto the PCB track connected to the FB pin
· A full ground plane will do much to enhance EMI per-
· All tracks should be as short and wide as possible
formance
· All components must be located as close to the IC as
A demo board schematic and layout is provided for consultation below:
possible
Rev. 1.10
9
March 11, 2010
HT77S10/HT77S11
TopOverlay View
TopLayer View
BottomLayer View
Rev. 1.10
10
March 11, 2010
HT77S10/HT77S11
Application Circuits
VOUT=3.3V
V
2 2 m H
IN
C 1
4 7 m F
R 3
S H D N
L B I
R 4
R E F
0 .1 m F
V O U T
O u tp u t 3 .3 V
O U T
L X
L
C 2
4 7 m H
R 5
L B O
G N D
F B
L : T D K S L F 7 0 4 5 T -2 2 0 M R 9 0 -P F
C 1 , C 2 : V is h a y 5 9 3 D 4 7 6 X 9 0 1 6 C 2
Figure 1
VOUT=5.0V
V
2 2 m H
IN
C 1
4 7 m F
L
R 3
S H D N
L B I
R 4
R E F
0 .1 m F
V O U T
O u tp u t 5 .0 V
O U T
L X
C 2
4 7 m H
R 5
L B O
G N D
F B
L : T D K S L F 7 0 4 5 T -2 2 0 M R 9 0 -P F
C 1 , C 2 : V is h a y 5 9 3 D 4 7 6 X 9 0 1 6 C 2
Figure 2
VOUT=1.8V~5.5V
V
V
O U T
= V
2 2 m H
IN
C 1
4 7 m F
L
O U T
L X
R 3
S H D N
L B I
R 4
R E F
0 .1 m F
G N D
R 1 )
R 2
O u tp u t A d j.
(1 .8 V ~ 5 .5 V )
x (1 +
C 2
4 7 m H
R 5
L B O
R E F
R 1
F B
R 2
L : T D K S L F 7 0 4 5 T -2 2 0 M R 9 0 -P F
C 1 , C 2 : V is h a y 5 9 3 D 4 7 6 X 9 0 1 6 C 2
Figure 3
Rev. 1.10
11
March 11, 2010
HT77S10/HT77S11
Package Information
8-pin SOP (150mil) Outline Dimensions
5
8
A
B
4
1
C
C '
G
H
D
E
a
F
· MS-012
Symbol
A
Nom.
Max.
0.228
¾
0.244
B
0.150
¾
0.157
C
0.012
¾
0.020
C¢
0.188
¾
0.197
D
¾
¾
0.069
E
¾
0.050
¾
F
0.004
¾
0.010
G
0.016
¾
0.050
H
0.007
¾
0.010
a
0°
¾
8°
Symbol
A
Rev. 1.10
Dimensions in inch
Min.
Dimensions in mm
Min.
Nom.
Max.
5.79
¾
6.20
B
3.81
¾
3.99
C
0.30
¾
0.51
C¢
4.78
¾
5.00
D
¾
¾
1.75
E
¾
1.27
¾
F
0.10
¾
0.25
G
0.41
¾
1.27
H
0.18
¾
0.25
a
0°
¾
8°
12
March 11, 2010
HT77S10/HT77S11
8-pin MSOP Outline Dimensions
8
5
E 1
1
4
E
D
A
L
A 2
e
R
0 .1 0
A 1
B
C
q
y
(4 C O R N E R S )
· MO-187
Symbol
Nom.
Max.
A
¾
¾
0.043
A1
0.000
¾
0.006
A2
0.030
¾
0.037
B
0.009
¾
0.013
C
0.003
¾
0.009
D
¾
0.012
¾
E
¾
0.193
¾
E1
¾
0.118
¾
e
¾
0.026
¾
L
0.016
¾
0.031
L1
¾
0.037
¾
y
¾
¾
0.004
q
0°
¾
8°
Symbol
Rev. 1.10
Dimensions in inch
Min.
Dimensions in mm
Min.
Nom.
Max.
A
¾
¾
1.10
A1
0.00
¾
0.15
A2
0.75
¾
0.95
B
0.22
¾
0.33
C
0.08
¾
0.23
D
¾
3.00
¾
E
¾
4.90
¾
E1
¾
3.00
¾
e
¾
0.65
¾
L
0.40
¾
0.80
L1
¾
0.95
¾
y
¾
¾
0.10
q
0°
¾
8°
13
March 11, 2010
HT77S10/HT77S11
Product Tape and Reel Specifications
Reel Dimensions
D
T 2
A
C
B
T 1
SOP 8N
Symbol
Description
Dimensions in mm
A
Reel Outer Diameter
330.0±1.0
B
Reel Inner Diameter
100.0±1.5
C
Spindle Hole Diameter
D
Key Slit Width
T1
Space Between Flange
T2
Reel Thickness
Rev. 1.10
13.0
+0.5/-0.2
2.0±0.5
12.8
+0.3/-0.2
18.2±0.2
14
March 11, 2010
HT77S10/HT77S11
Carrier Tape Dimensions
P 0
D
P 1
t
E
F
W
B 0
C
D 1
P
K 0
A 0
R e e l H o le
IC
p a c k a g e p in 1 a n d th e r e e l h o le s
a r e lo c a te d o n th e s a m e s id e .
SOP 8N
Symbol
Description
Dimensions in mm
Carrier Tape Width
P
Cavity Pitch
8.0±0.1
E
Perforation Position
1.75±0.1
F
Cavity to Perforation (Width Direction)
5.5±0.1
D
Perforation Diameter
1.55±0.1
D1
Cavity Hole Diameter
P0
Perforation Pitch
4.0±0.1
P1
Cavity to Perforation (Length Direction)
2.0±0.1
A0
Cavity Length
6.4±0.1
B0
Cavity Width
5.2±0.1
K0
Cavity Depth
2.1±0.1
t
Carrier Tape Thickness
C
Cover Tape Width
Rev. 1.10
12.0
+0.3/-0.1
W
1.50
+0.25/-0.00
0.30±0.05
9.3±0.1
15
March 11, 2010
HT77S10/HT77S11
Holtek Semiconductor Inc. (Headquarters)
No.3, Creation Rd. II, Science Park, Hsinchu, Taiwan
Tel: 886-3-563-1999
Fax: 886-3-563-1189
http://www.holtek.com.tw
Holtek Semiconductor Inc. (Taipei Sales Office)
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Tel: 886-2-2655-7070
Fax: 886-2-2655-7373
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Tel: 86-755-8616-9908, 86-755-8616-9308
Fax: 86-755-8616-9722
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46729 Fremont Blvd., Fremont, CA 94538
Tel: 1-510-252-9880
Fax: 1-510-252-9885
http://www.holtek.com
Copyright Ó 2010 by HOLTEK SEMICONDUCTOR INC.
The information appearing in this Data Sheet is believed to be accurate at the time of publication. However, Holtek assumes no responsibility arising from the use of the specifications described. The applications mentioned herein are used
solely for the purpose of illustration and Holtek makes no warranty or representation that such applications will be suitable
without further modification, nor recommends the use of its products for application that may present a risk to human life
due to malfunction or otherwise. Holtek¢s products are not authorized for use as critical components in life support devices
or systems. Holtek reserves the right to alter its products without prior notification. For the most up-to-date information,
please visit our web site at http://www.holtek.com.tw.
Rev. 1.10
16
March 11, 2010