MIC2182
Micrel
MIC2182
High-Efficiency Synchronous Buck Controller
Final Information
General Description
Micrel’s MIC2182 is a synchronous buck (step-down) switch-
ing regulator controller. An all N-channel synchronous archi-
tecture and powerful output drivers allow up to a 20A output
current capabilty. The PWM and skip-mode control scheme
allows efficiency to exceed 95% over a wide range of load
current, making it ideal for battery powered applications, as
well as high current distributed power supplies.
The MIC2182 operates from a 4.5V to 32V input and can
operate with a maximum duty cycle of 86% for use in low-
dropout conditions. It also features a shutdown mode that
reduces quiescent current to 0.1µA.
The MIC2182 achieves high efficiency over a wide output
current range by automatically switching between PWM and
skip mode. Skip-mode operation enables the converter to
maintain high efficiency at light loads by turning off circuitry
pertaining to PWM operation, reducing the no-load supply
current from 1.6mA to 600µA. The operating mode is inter-
nally selected according to the output load conditions. Skip
mode can be defeated by pulling the PWM pin low which
reduces noise and RF interference.
The MIC2182 is available in a 16-pin SOP (small-outline
package) and SSOP (shrink small-outline package) with an
operating range from –40°C to +85°C.
Features
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4.5V to 32V Input voltage range
1.25V to 6V Output voltage range
95% efficiency
300kHz oscillator frequency
Current sense blanking
5Ω impedance MOSFET Drivers
Drives N-channel MOSFETs
600µA typical quiescent current (skip-mode)
Logic controlled micropower shutdown (I
Q
< 0.1µA)
Current-mode control
Cycle-by-cycle current limiting
Built-in undervoltage protection
Adjustable undervoltage lockout
Easily synchronizable
Precision 1.245V reference output
0.6% total regulation
16-pin SOP and SSOP packages
Frequency foldback overcurrent protection
Sustained short-circuit protection at any input voltage
20A output current capability
DC power distribution systems
Notebook and subnotebook computers
PDAs and mobile communicators
Wireless modems
Battery-operated equipment
Applications
Typical Application
V
IN
4.5V to 30V*
R7
100k
D2
MIC2182-3.3BSM
10
11
SD103BWS
VIN
VDD
C5
0.1µF
6
2
BST
EN/UVLO HSD
PWM
VSW
LSD
14
16
15
13
12
8
9
7
C6
0.1µF
C9
4.7µF
16V
C11
22uf
35V
x2
Q2*
Si4884
Q1*
Si4884
L1
10µH
D1
B140
V
OUT
3.3V/4A
C7
220uf
10V
×2
GND
R2
0.02Ω
C4
1nF
1
3
SS
COMP
SYNC
PGND
CSH
VOUT
VREF
SGND
4
C3
0.1µF
C2
2.2nF
GND
R1
2k
5
C13, 1nF
* 30V maximum input voltage limit is due
to standard 30V MOSFET selection.
C1
0.1µF
See “Application Information” section for
5V to 3.3V/10A and other circuits.
4.5V–30V* to 3.3V/4A Converter
Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com
June 2000
1
MIC2182
MIC2182
Micrel
Ordering Information
Part Number
MIC2182BM
MIC2182-3.3BM
MIC2182-5.0BM
MIC2182BSM
MIC2182-3.3BSM
MIC2182-5.0BSM
Voltage
Adjustable
3.3V
5.0V
Adjustable
3.3V
5.0V
Temperature Range
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
Package
16-pin narrow SOP
16-pin narrow SOP
16-pin narrow SOP
16-pin narrow SSOP
16-pin narrow SSOP
16-pin narrow SSOP
Pin Configuration
MIC2182
SS 1
PWM 2
COMP 3
SGND 4
SYNC 5
EN/UVLO 6
FB
7
CSH 8
16 HSD
15 VSW
14 BST
13 LSD
12 PGND
11 VDD
10 VIN
9 VOUT
SS 1
PWM 2
COMP 3
SGND 4
SYNC 5
EN/UVLO 6
VREF
7
CSH 8
MIC2182-x.x
16 HSD
15 VSW
14 BST
13 LSD
12 PGND
11 VDD
10 VIN
9 VOUT
Adjustable
16-pin SOP (M)
16-Pin SSOP (SM)
Fixed
16-pin SOP (M)
16-Pin SSOP (SM)
MIC2182
2
June 2000
MIC2182
Micrel
Pin Description
Pin Number
1
Pin Name
SS
Pin Function
Soft-Start (External Component): Connect external capacitor to ground to
reduce inrush current by delaying and slowing the output voltage rise time.
Rise time is controlled by an internal 5µA current source that charges an
external capacitor to V
DD
.
PWM/Skip-Mode Select (Input): Low sets PWM-mode operation. 1nF
capacitor to ground sets automatic PWM/skip-mode selection.
Compensation (Output): Internal error amplifier output. Connect to capacitor
or series RC network to compensate the regulator control loop.
Small Signal Ground (Return): Route separately from other ground traces to
the (–) terminal of C
OUT
.
Frequency Synchronization (Input): Optional. Connect to external clock
signal to synchronize the oscillator. Leading edge of signal above the
threshold terminates the switching cycle. Connect to SGND if unused.
Enable/Undervoltage Lockout (Input): Low-level signal powers down the
controller. Input below the 2.5V threshold disables switching and functions
as an accurate undervoltage lockout (UVLO). Input below the threshold
forces complete micropower (< 0.1µA) shutdown.
Reference Voltage (Output): 1.245V output. Requires 0.1µf capacitor to
ground.
Feedback (Input): Regulates FB pin to 1.245V. See “Application Information”
for resistor divider calculations.
Current-Sense High (Input): Current-limit comparator noninverting input. A
built-in offset of 100mV between CSH and V
OUT
pins in conjunction with the
current-sense resistor set the current-limit threshold level. This is also the
positive input to the current sense amplifier.
Current-Sense Low (Input): Output voltage feedback input and inverting
input for the current limit comparator and the current sense amplifier.
[Battery] Unregulated Input (Input): +4.5V to +32V supply input.
5V Internal Linear-Regulator (Output): V
DD
is the external MOSFET gate
drive supply voltage and an internal supply bus for the IC. Bypass to SGND
with 4.7µF. V
DD
can supply up to 5mA for external loads.
MOSFET Driver Power Ground (Return): Connects to source of synchro-
nous MOSFET and the (–) terminal of C
IN
Low-Side Drive (Output): High-current driver output for external synchronous
MOSFET. Voltage swing is between ground and V
DD
.
Boost (Input): Provides drive voltage for the high-side MOSFET driver. The
drive voltage is higher than the input voltage by V
DD
minus a diode drop.
Switch (Return): High side MOSFET driver return.
High-Side Drive (Output): High-current driver output for high-side MOSFET.
This node voltage swing is between ground and V
IN
+ 5V – V
diode drop
.
2
3
4
5
PWM
COMP
SGND
SYNC
6
EN/UVLO
7 (fixed)
7 (adj)
8
VREF
FB
CSH
9
10
11
VOUT
VIN
VDD
12
13
14
15
16
PGND
LSD
BST
VSW
HSD
June 2000
3
MIC2182
MIC2182
Micrel
Absolute Maximum Ratings
(Note 1)
Analog Supply Voltage (V
IN
) ....................................... +34V
Digital Supply Voltage (V
DD
) ......................................... +7V
Driver Supply Voltage (B
ST
) .................................... V
IN
+7V
Sense Voltage (V
OUT
, C
SH
) ............................. 7V to –0.3V
Sync Pin Voltage (V
SYNC
) ................................ 7V to –0.3V
Enable Pin Voltage (V
EN/UVLO
) ...................................... V
IN
Power Dissipation (P
D
)
SOP ................................................ 400mW @ T
A
= 85°C
SSOP ............................................. 270mW @ T
A
= 85°C
Ambient Storage Temperature (T
S
) ......... –65°C to +150°C
ESD,
Note 3
Operating Ratings
(Note 2)
Analog Supply Voltage (V
IN
) ........................ +4.5V to +32V
Ambient Temperature (T
A
) ......................... –40°C to +85°C
Junction Temperature (T
J
) ....................... –40°C to +125°C
Package Thermal Resistance
SOP
(θ
JA
) .......................................................... 100°C/W
SSOP
(θ
JA
) ........................................................ 150°C/W
Electrical Characteristics
V
IN
= 15V; SS = open; V
PWM
= 0V; V
SHDN
= 5V; I
LOAD
= 0.1A; T
A
= 25°C,
bold
values indicate –40°C
≤
T
A
≤
+85°C;
Note 4;
unless
noted
Parameter
MIC2182 [Adjustable], (Note 5)
Feedback Voltage Reference
Feedback Voltage Reference
Feedback Voltage Reference
Feedback Bias Current
Output Voltage Range
Output Voltage Line Regulation
Output Voltage Load Regulation
Output Voltage Total Regulation
MIC2182-3.3
Output Voltage
Output Voltage
Output Voltage
Output Voltage Line Regulation
Output Voltage Load Regulation
Output Voltage Total Regulation
MIC2182-5.0
Output Voltage
Output Voltage
Output Voltage
Output Voltage Line Regulation
Output Voltage Load Regulation
Output Voltage Total Regulation
Input and VDD Supply
PWM Mode
Skip Mode
Shutdown Quiescent Current
Digital Supply Voltage (V
DD
)
Undervoltage Lockout
V
PWM
= 0V, excluding external MOSFET gate drive current
I
L
= 0mA, V
PWM
floating (1nF capacitor to ground)
V
EN/UVLO
= 0V
I
L
= 0mA to 5mA
V
DD
upper threshold (turn on threshold)
V
DD
lower threshold (turn off threshold)
4.7
4.2
4.1
1.6
600
0.1
2.5
1500
5
5.3
mA
µA
µA
V
V
V
6.5V < V
IN
< 32V, 0 < V
CSH
– V
OUT
< 75mV
V
IN
= 6.5V to 32V, V
CSH
– V
OUT
= 50mV
25mV < (V
CSH
– V
OUT
) < 75mV (PWM mode only)
0mV < (V
CSH
– V
OUT
) < 75mV (full load range) 6.5V < V
IN
< 32V
4.95
4.90
4.85
5.0
5.0
5.0
0.03
0.5
0.8
5.05
5.10
5.150
V
V
V
%/V
%
%
4.5V < V
IN
< 32V, 0 < V
CSH
– V
OUT
< 75mV
V
IN
= 4.5V to 32V, V
CSH
– V
OUT
= 50mV
25mV < (V
CSH
– V
OUT
) < 75mV (PWM mode only)
0mV < (V
CSH
– V
OUT
) < 75mV (full load range) 4.5V < V
IN
< 32V
3.267
3.234
3.201
3.3
3.3
3.3
0.03
0.5
0.8
3.333
3.366
3.399
V
V
V
%/V
%
%
V
IN
= 4.5V to 32V, V
CSH
– V
OUT
= 50mV
25mV < (V
CSH
– V
OUT
) < 75mV (PWM mode only)
0mV < (V
CSH
– V
OUT
) < 75mV (full load range) 4.5V < V
IN
< 32V
1.25
0.03
0.5
0.6
4.5V < V
IN
< 32V, 0 < V
CSH
– V
OUT
< 75mV
1.233
1.220
1.208
1.245
1.245
1.245
10
6
1.257
1.270
1.282
V
V
V
nA
V
%/V
%
%
Condition
Min
Typ
Max
Units
MIC2182
4
June 2000
MIC2182
Parameter
Condition
Min
Typ
Max
Micrel
Units
Reference Output (Fixed Versions Only)
Reference Voltage
Reference Line Regulation
Reference Load Regulation
Enable/UVLO
Enable Input Threshold
UVLO Threshold
Enable Input Current
Soft Start
Soft-Start Current
Current Limit
Current-Limit Threshold Voltage
Error Amplifier
Error Sense Amplifier Gain
Current Amp
Current Sense Amplifier Gain
Oscillator Section
Oscillator Frequency
Maximum Duty Cycle
Minimum On-Time
SYNC Threshold Level
SYNC Input Current
SYNC Minimum Pulse Width
SYNC Capture Range
Frequency Foldback Threshold
Foldback Frequency
Gate Drivers
Rise/Fall Time
Output Driver Impedance
Driver Nonoverlap Time
PWM Input
PWM Input Current
Note 1.
Note 2.
Note 3.
Note 4.
Note 5.
Note 6.
1.220
6V < V
IN
< 32V
0µA < I
REF
< 100µA
0.6
2.2
V
EN/UVLO
= 5V
V
SS
= 0V
V
CSH
= V
OUT
–3.5
1.245
1
2
1.270
V
mV
mV
1.1
2.5
0.1
1.6
2.8
5
V
V
µA
µA
–5
–6.5
75
100
135
mV
20
2.0
270
300
86
330
kHz
%
V
OUT
= V
OUT(nominal)
+ 200mV
0.7
V
SYNC
= 5V
200
Note 6
measured at VOUT pin
330
0.75
140
1.3
0.1
250
1.9
5
ns
V
µA
ns
kHz
0.95
60
1.15
V
kHz
C
L
= 3000pF
source
sink
60
5
3.5
80
8.5
6
ns
Ω
Ω
ns
µA
V
PWM
= 0V
–10
Exceeding the absolute maximum rating may damage the device.
The device is not guaranteed to function outside its operating rating.
Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF.
25°C limits are 100% production tested. Limits over the operating temperature range are guaranteed by design and are not production tested.
V
IN
> 1.3
×
V
OUT
(for the feedback voltage reference and output voltage line and total regulation).
See applications information for limitations on the maximum operating frequency.
June 2000
5
MIC2182
嵌入式系统
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